Rice. 1. Scheme of preparation and admission of gas and smoke protectors to work in RPE

In addition, personnel admitted by the military medical (medical) commission to use RPE are required to undergo an annual medical examination.

Personnel from among the gas and smoke protectors undergo certification in the manner prescribed by the rules for attestation of personnel of the State Fire Service for the right to work in personal protective equipment for respiratory and vision organs (Appendix 1).

The training of personnel in order to obtain the qualification (specialty) of a senior master (master) of the GDZS is organized by the territorial bodies of the EMERCOM of Russia in training centers, in the prescribed manner. Personnel temporarily acting as full-time senior masters (masters) of the GDZS must have appropriate training.

The admission of personnel who have completed training to perform duties as a senior foreman (master) of the GDZS is issued by order of the territorial body of the EMERCOM of Russia.

For practical training of gas and smoke protectors for work in RPE in an environment unsuitable for breathing, each local fire brigade garrison should be equipped with heat and smoke chambers (smoke chambers) or training complexes, as well as firing lanes for the psychological training of firefighters.

2. BREATHING APPARATUS WITH COMPRESSED AIR

2.1. Appointment of breathing apparatus

A breathing apparatus with compressed air is an insulating reservoir apparatus in which the air supply is stored in pressurized cylinders in a compressed state. The breathing apparatus operates according to an open breathing scheme, in which air is taken from the cylinders for inhalation, and exhalation is made into the atmosphere.

Breathing apparatus with compressed air are designed to protect the respiratory organs and eyesight of firefighters from the harmful effects of an unbreathable, toxic and smoky gaseous environment when extinguishing fires and performing rescue operations.

2.2. Main performance characteristics

Consider the AP-2000 breathing apparatus, which operates according to an open breathing scheme (inhalation from the apparatus - exhalation into the atmosphere) and is intended for:

protection of respiratory organs and human vision from the harmful effects of a toxic and smoky gaseous environment when extinguishing fires and emergency rescue operations in buildings, structures and industrial facilities; evacuation of the victim from an area with unbreathable gas

environment when used with a rescue device.

The technical characteristics of the device and its components comply with the requirements of fire safety standards NPB-165-2001, NPB-178-99, NPB-190-2000.

The device is operational at air pressure in the cylinder (cylinders) from 1.0 to 29.4 MPa (from 10 to 300 kgf/cm2). In the undermask space of the front part* of the device, during breathing, excess pressure is maintained at pulmonary ventilation up to 85 l/min and the ambient temperature range from -40 to +60 °C.

Excessive pressure in the undermask space at zero air flow - (300 ± 100) Pa ((30 ± 10) mm of water column).

The time of the protective action of the apparatus with pulmonary ventilation of 30 l / min (moderate work) corresponds to the values ​​\u200b\u200bspecified in Table. one.

						Table 1
	Time of protective action of the apparatus AP-2000 Standard**
				Balloon parameters
	protective				Technical		Warranty,
	actions,	device,			characteristics,
					l/kgf/cm2
				Steel
				metal composite
				metal composite
				metal composite
				metal composite

The volume fraction of carbon dioxide in the inhaled mixture is not more than 1.5%.

* The front part of the device is a full-face panoramic mask, hereinafter referred to as the mask.

**AP-2000 Standard - complete with mask PM-2000 and lung machine AP2000

The actual resistance to breathing on exhalation during the entire time of the protective action of the device and with pulmonary ventilation of 30 l/min (moderate work) does not exceed: 350 Pa (35 mm of water column) - at an ambient temperature of +25 °C; 500 Pa (50 mm w.g.) - at an ambient temperature of -40 °C.

Air consumption during operation of the additional supply device (bypass) - not less than 70 l / min in the non-pressure range from 29.4 to 1.0 MPa (from 300 to 10 kgf / cm2).

The valve of the lung machine of the rescue device opens at a vacuum of 50 to 350 Pa (from 5 to 35 mm of water column) at a flow rate of 10 l/min.

The high and reduced pressure systems of the apparatus are sealed, and after closing the cylinder valve (cylinder valves), the pressure drop does not exceed 2.0 MPa (20 kgf/cm) per minute.

The high and reduced pressure systems of the apparatus with the connected rescue device are hermetic, and after closing the cylinder valve (cylinder valves), the pressure drop does not exceed 1.0 MPa (10 kgf/cm2) per minute.

The air duct system of the device with a connected rescue device is sealed, while creating a vacuum and overpressure of 800 Pa (80 mm of water column), the pressure change in it does not exceed 50 Pa (5 mm of water column) per minute.

The alarm device is triggered when the pressure in the cylinder drops to 6–0.5 MPa (60–5 kgf/cm2), while the signal sounds for at least 60 seconds.

The sound pressure level of the signaling device (when measured directly at the sound source) is at least 90 dBA. In this case, the frequency response of the sound created by the signaling device is in the pre-

cases 800 ... 4000 Hz.

Air consumption during operation of the signaling device - no more than 5 l / min. The cylinder valve is tight in the "Open" and "Closed" positions when

all tank pressures.

The valve is operational for at least 3000 opening and closing cycles.

The pressure at the outlet of the reducer (without flow) is:

not more than 0.9 MPa (9 kgf/cm2) at pressure in the cylinder of the apparatus 27.45...29.4

MPa (280...300 kgf/cm2);

not less than 0.5 MPa (5 kgf / cm2) at a pressure in the cylinder of the device 1.5 MPa

(15 kgf/cm2).

The safety valve of the reducer opens when the pressure at the outlet of the reducer is not more than 1.8 MPa (18 kgf/cm2).

Cylinders of the apparatus withstand at least 5000 loading cycles (fillings) between zero and working pressure.

The term for re-examination of the cylinders of the apparatus is: 3 years for metal-composite cylinders; 5 years for a steel cylinder SNPP "SPLAV";

6 years (primary), 5 years - subsequent for the company's steel cylinder

The service life of the cylinders of the apparatus is: 16 years for steel "FABER";

11 years for the steel GNPP "SPLAV";

10 years for metal-composite CJSC NPP Mashtest;

15 years for metal composite "LUXFER LCX". The average service life of the apparatus is 10 years. The mass of the mask does not exceed 0.7 kg.

According to the type of climatic version, the device belongs to the version of the location category 1 according to GOST 15150-96, but is designed for use at an ambient temperature of -40 to +60 ° C, relative humidity up to 100%, atmospheric pressure from 84 to 133 kPa (from 630 to 997.5 mm Hg).

The device is resistant to aqueous solutions of surface-active substances (surfactants).

Mask, lung governed demand valve and rescue device are resistant to disinfectants used in sanitation:

rectified ethyl alcohol GOST 5262-80; aqueous solutions: hydrogen peroxide (6%), chloramine (1%), boric

acid (8%), potassium permanganate (0.5%).

2.3. The device and principle of operation of breathing apparatus

The basis of the apparatus (Fig. 2) is suspension system, which serves to mount all parts of the device on it and fasten it to the human body, including the base 14 , shoulder straps 1 , end straps 13 and waist belt 17 .

Rice. 2. Breathing apparatus AP-2000: 1 - shoulder straps; 2 - low pressure hose; 3 - balloon; 4 - signal device hose; 5 - whistle; 6 - housing of the signaling device; 7 - pressure gauge; 8 - nipple; 9 - high pressure hose; 10 - valve handwheel; 11 - rescue device lock; 12 - hose; 13 - trailer belts; 14 - base; 15 - belt; 16 - lock; 17 - waist belt

The following components of the device are mounted on the suspension system: cylinder with valve 3; gearbox (Fig. 3), fixed on base 14 with a bracket; a signaling device with a pressure gauge 7 , a body 6 , a whistle 5 and a hose 4 coming from the gearbox along the left shoulder strap; low pressure hose 2, laid along the right shoulder belt, connecting the gearbox with the lung machine (Fig. 4, 6); hose 12 with lock 11 for connecting the rescue device (Fig. 5) to the device, coming from the gearbox along the right side of the waist belt; high pressure hose 9 with a plug nipple 8 for recharging the device by bypass, coming from the gearbox along the left side of the waist belt.

For more convenient mounting of the device on the user's body, the suspension system provides for the possibility of adjusting the length of the straps.

To adjust the position of the shoulder straps, depending on the body size of the user, two groups of grooves are provided in the upper part of the base of the device.

Cylinder with valve is a container for storing a supply of compressed air suitable for breathing. Cylinder 3 (see Fig. 2) is tightly packed into the base cradle 14, while the upper part of the cylinder is fastened to the base with a belt 15 with a lock 16 having a latch that prevents accidental opening of the lock.

To protect against damage to the surface of metal-composite cylinders

And a cover can be applied to extend their service life. The cover is made of thick red fabric. A white reflective tape is sewn on the surface of the cover, which allows you to control the location of the user of the device in conditions of poor visibility.

signaling device designed to give an audible signal,

warning the user about reducing the air pressure in the cylinder to 5.5 ... 6.8 MPa (55 ... 68 kgf / cm2), and consists of a body 6 (see Fig. 2) and a whistle 5 and a pressure gauge 7 screwed into it. The manometer of the apparatus is designed to control the pressure of compressed air in the cylinder with the valve open.

The reducer (Fig. 3) is designed to reduce the pressure of compressed air

And feeding it to the lung machines of the device and the rescue device.

On the housing 1 of the gearbox there is a threaded fitting 3 with a handwheel 2 for connection with the cylinder valve.

The built-in safety valve 6 of the reducer protects the low-pressure cavity of the apparatus from an excessive increase in pressure at the outlet of the reducer.

The gearbox provides operation without adjustment during the entire service life and is not subject to disassembly. The reducer is sealed with sealing paste; in case of violation of the safety of the seals, claims to the operation of the reducer are not accepted by the manufacturer.

Depending on the configuration, the apparatus may include two types of masks: PM-2000 with lung machine 9V5.893.497 (option 1); "Pana Sil" made of neoprene or silicone with a rubber or mesh headband with lung machine 9B5.893.460 (option 2).

Rice. 3. Reducer: 1 - reducer housing; 2 - handwheel; 3 - threaded fitting; 4 - ring 9V8.684.909; 5 - cuff; 6 - safety valve; 7 - filling

The mask (Fig. 4) is designed to isolate the respiratory organs and human vision from the environment, supply air from the lung machine 6 for breathing through the inhalation valves 3 located in the mask 2 , and remove the exhaled air through the exhalation valve 8 into the environment.

Rice. 4. Mask PM-2000 with lung machine: 1 - mask body; 2 - mask holder; 3 - cla-

pans of inspiration; 4 - intercom; 5 - nut; 6 - lung machine; 7 - multifunctional button; 8 - exhalation valve; 9 - hose lung machine; 10 - strap; 11 - lock; 12 - headband straps; 13 - valve box cover

The mask body 1 has a built-in intercom 4 that provides the ability to transmit voice messages.

IN the design of the mask provides for the possibility of adjusting the length of the headband straps 12 .

Lung machine 6(Fig. 4) is designed to supply air to the internal cavity of the mask with excess pressure, as well as to turn on additional continuous air supply in case of failure of the lung machine or lack of air to the user. The lung machine is attached to the mask with the help of

I screw nuts with M45 × 3 thread.

rescue device(Fig. 5) is designed to protect the respiratory organs and eyesight of the injured person when he is rescued by the user of the apparatus and removed from the zone with a gaseous environment unsuitable for breathing.

The rescue device includes:

mask worn in the bag 1, which is the front part of the ShMP-1

height 2 GOST 12.4.166;

lung governed demand valve 2 with bypass button 2.1 and hose 3 .

The lung machine is attached to the mask using a nut 2.2 with a round thread

Loy 40×4.

Rice. 5. Rescue device: 1 -

mask; 2 - lung machine: 2.1 - bypass button;

2.2 - nut; 3 - hose

To connect the rescue device to the device, hose 12 with a quick-release lock is used (see Fig. 2), which the manufacturer installs on the device when ordering a rescue device. The design of the lock eliminates accidental undocking during operation.

In the absence of an order, plug 11 is installed on the gearbox (Fig. 6).

Rice. 6. Schematic diagram of the apparatus AP-2000: 1 - lung machine: 1.1 - valve;

1.2, 1.9, 1.10 - spring; 1.3 - ring; 1.4 - membrane; 1.5 - valve seat; 1.6 - support; 1.7 - stock; 1.8 - button; 1.11 - cover; 2 - mask: 2.1 - panoramic glass; 2.2 - inhalation valves; 2.3 - exhalation valve; 3 - balloon with valve: 3.1 - balloon; 3.2 - valve; 3.3 - handwheel; 3.4 - ring 9v8.684.919; 4 - signaling device: 4.1 - pressure gauge; 4.2 - whistle; 4.3 - retaining ring; 4.4 - ring; five - rescue device: 5.1 - hose; 5.2 - lung machine; 5.3 - mask; 5.4 - bypass button; 5.5 - nipple; 6 - high pressure hose: 6.1 - ring; 7 - hose for connecting the rescue device: 7.1 - lock; 7.2 - sleeve; 7.3 - ball; 7.4 - valve; 8 - reducer: 8.1 - valve; 8.2 - spring; 8.3 - ring 9V8.684.909; nine - a hose with a plug-in nipple for recharging cylinders; 10 - lung machine hose; 11, 12 - traffic jams; A, B - cavities

Structurally, the lung machine of the rescue device differs from the lung machine of the device in the absence of the possibility of creating excess pressure and the type of thread for attaching to the mask.

Device for recharging the apparatus with air provides an opportunity

the ability to recharge the cylinder of the device by bypassing without interrupting the operation of the device.

The device includes a high-pressure hose 9 (see Fig. 2) with a plug-in nipple 8, which is installed on the device by the manufacturer when ordering a device for recharging, and a hose with a half-coupling for connecting to a high pressure source.

In the absence of an order for the device, plug 12 is installed on the gearbox (Fig. 6).

Device management(see Fig. 2) is carried out using the valve handwheel 10 .

The opening of the valve occurs when the handwheel is rotated counterclockwise until it stops.

To close the valve, the handwheel is rotated clockwise until it stops without much effort.

The activation of the mechanism of the lung machine with the valve open is carried out automatically - by the effort of the user's first breath.

Switching off the mechanism of the lung machine is carried out forcibly as follows: press the bypass button all the way, fix it for 1-2 s, then slowly release it.

Turning on the additional air supply device (bypass) is carried out by smoothly pressing the bypass button and holding it in this position.

Air pressure control is carried out by pressure gauge 7, mounted on a hose 4, which is placed on the left shoulder strap of the suspension system. Gauge scale is photoluminescent for use in low light and in the dark.

On fig. 6. A schematic diagram of the apparatus AP-2000 is shown.

Before turning on the device, the valve (s) 3.2 is closed, the valve 8.1 of the gearbox 8 is opened by the force of the spring 8.2, the lung machine 1 is turned off by pressing the button 1.8 all the way.

When switched on, the user opens the valve(s) 3.2. Compressed air contained in the cylinder 3.1, through an open valve 3.2 enters the inlet of the gearbox 8. At the same time, air enters the signal device 4 through the high pressure hose 6 .

Under the action of air pressure coming from the inlet of the gearbox into cavity B, the spring 8.2 is compressed and the valve 8.1 closes. When air is taken through hose 9, the pressure in cavity B decreases and valve 8.1 opens by a certain amount under the action of spring 8.2.

An equilibrium state is established, in which air with a pressure reduced to a working value determined by the force of the spring 8.2 flows through the hose 9 to the inlet of the lung machine 1 and into the cavity of the hose 7 .

With the lung machine 1 turned off and the mask 2 removed from the user's face, the button latch 1.8 is engaged with the membrane 1.4, which is retracted to the extreme non-working position by the force of the spring 1.9 and does not touch the support 1.6, and the valve 1.1 is closed by the force of the spring 1.2. When the mask is put on the face during the first breath, a vacuum is formed in the cavity A of the lung machine 1. Under the action of the pressure difference, the membrane 1.4 flexes, jumps off the latch of the button 1.8 and goes into working condition. Under the force of the spring 1.10, the membrane 1.4 presses on the support 1.6 and deflects the valve 1.1 from the seat 1.5 through the stem 1.7.

If the lung machine fails or it is necessary to purge the submask space, the valve 1.1 is opened by pressing and holding the bypass button 1.8, while the air flows continuously. It should be remembered that the inclusion of additional continuous supply reduces the time of the protective action of the device.

The lung machine, using a spring 1.10 together with a spring-loaded exhalation valve 2.3 of the mask, creates an air flow with excess pressure, which first enters the panoramic glass 2.1, preventing it from fogging, and then through the inhalation valves 2.2 - for breathing.

Human beings need air to function. It contains vital oxygen and nitrogen. But sometimes a situation may arise when it is impossible to get access to the usual air. This problem is relevant for divers, firefighters and many others. And in these cases, breathing apparatus with compressed air comes to the rescue. What are they? What variety is there? How to look after them? These and a number of other questions will be answered in this article.

general information

And let's start with the terminology. So, breathing apparatus with compressed air (also known as SCBA) is an insulating reservoir device, which provides for the possibility of storing substances necessary for the functioning of the human body. As a rule, a balloon is selected for this. The air in it is stored in a compressed state. DAVS work according to an open breathing pattern. In other words, inhalation is carried out from the balloon, and exhalation is carried out into the surrounding atmosphere. What do compressed air breathing apparatuses look like in general terms? The scheme of their device usually assumes the presence of:

1. Cylinder with valve.
2. Hanging system.
3. Reducer with safety valve.
4. Lung machine with air hose.
5. Sound signaling device.
6. Exhalation valve.
7. Devices for additional air supply.
8. pressure gauge.
9. Front part with intercom.

Also can be attached additionally:

1. A fitting that is used for quick refueling of cylinders.
2. Rescue device connected to a breathing apparatus.
3. Quick connector for connecting a life-saving appliance or ventilator.

When trying to classify AHRS, the question immediately arises of what to choose as a reference point. So, if you look at the design, it will be one thing, the purpose is completely different. Questions about air consumption, its reserves and much more are also relevant. Therefore, in order not to get lost among the three pines in the future, let's deal with all the species diversity.

Classification of breathing apparatus

With compressed air, they do not need to be. If we consider the design, then they are created:

1. Open circuit. It is to them that the considered breathing apparatus with compressed air belongs.
2. Closed loop. They run on compressed, liquefied or generated oxygen. Quite uncommon due to complex maintenance, as well as high fire hazard.

In addition, the classification is still carried out on the basis of the principle of their action: non / autonomous. If we talk about the use in difficult conditions (for example, for firefighters), then such devices belong to the second type. And this is not surprising - who knows where you have to climb.

In addition, there are lung machines with excess air pressure under the front of the device and without it. These devices are more focused on people who have to work in high temperatures. For example, firefighters. Excessive pressure in this case is necessary in order to protect a person from a smoky and toxic gas environment during fire extinguishing. After all, they perform their duties in extreme conditions, in which being without special breathing apparatus is guaranteed to cause health problems or even be fatal. Structurally, they are an insulated gas mask that does not involve the use of ambient air.

Interaction with the design: check

Respiratory protection in case of fire or deep sea diving is a priority. And in this case, it is extremely important that everything works without problems. Therefore, the design must be carefully and carefully checked. Previously, a list of what is included in it has already been presented. Now let's look at the intended purpose of each component and why you need to check the breathing apparatus with compressed air:

1. The front part - allows you to protect human organs and provides the usual working conditions for the whole organism.
2. One/two/three cylinders are needed to store compressed air. To prevent it from getting lost, they are equipped with a shut-off valve.
3. The flexible hose system provides air supply to the breathing zone.
4. A manometer is needed to determine the residues.
5. The alarm mechanism warns of the imminent stoppage of work and that you should leave the danger zone.
6. The charging of the cylinder is carried out thanks to high-pressure compressors, which are equipped with a system for filtering and drying the surrounding air.

For operational preparation of equipment in the middle of the process of work and further activities, additional rescue devices can be used. Their purpose is to quickly restore air supplies. If everything is done correctly, then a person will be created comfortable breathing conditions, in which reserves will be spent economically, and third-party chemical components will also be absent. When inspecting the structure, it is necessary to pay attention to the signaling mechanism - you need to make sure that it works without problems. All this will save your life from possible problems.

However, it should be noted that all these devices have a significant weight and dimensions, and the cylinders also need periodic recharging.

And a little about gas masks

For most people, this topic relates exclusively to civil defense. Well, it should be noted that gas masks have a much wider application than they are accustomed to attribute. And this is not surprising, because almost no attention is paid to other aspects. For example, it is difficult for many to imagine what an insulated gas mask is. It refers to a greater extent exclusively to firefighters. The insulating gas mask allows you to maintain high mobility, while protecting against harmful gases. After all, it is no secret that the vast majority of those killed in fires, before burning out, get carbon monoxide poisoning and lose consciousness.

The insulating gas mask works on the principle of scuba gear. It should be noted that in it the compressed air is under extremely high pressure. If the valve bursts, then if it hits a person, significant injuries will be inflicted on him, perhaps even incompatible with life. Since these devices are small, the operating time with them is 30-40 minutes. Usually this is more than enough. But still, firefighters often carry several spares with them.

By the way, gas masks can work not only with air, but also with oxygen. In this case, their shelf life can reach four hours. This advantage is used when working in mines, subways and other similar structures. But at the same time there is one significant minus - teeth deteriorate very quickly. If you constantly work in such an apparatus, then they will crumble as if they were made of plaster. Therefore, an oxygen insulating gas mask is used quite rarely. Again, only under adverse conditions when other devices are not suitable. That is, initially, the air supply can be calculated and the necessary actions can be assessed, and then the appropriate choice can be made.

The nuances of work

The pressure under which the air is in the cylinder is estimated at 300 atmospheres by default. In the future, this indicator is influenced by the frequency and depth of breaths. It is on this that the internal pressure and the time of activity with protection depend. Many may have a question: if work in breathing apparatus with compressed air takes place in such conditions, then how does a person not flatten inside the mask? This fact has a very simple explanation: the thing is that when he goes through the hoses, he has to go through a special gearbox. It sprays air with a thin (but powerful) stream, creating a pressure of two atmospheres in the mask. If the gearbox fails, then the air will not smear the person, but its supply will simply be stopped.

It should also be noted caution in working with rooms in which there are toxic and dangerous gas mixtures. Let's look at one important example. Movies often show how a lone firefighter rushes ahead to pull someone out. In reality, this is contrary to safety regulations. If firefighters enter a dangerous room, then their link should consist of at least three people (two, if more is not possible for certain reasons). Also, according to safety regulations, one person should always stand outside. He calculates the remaining time for the link, estimates when they should leave and the like.

It should be noted that this moment is often ignored, and in practice everyone who has respiratory protection equipment in case of fire goes inside the object.

What is the difference between different devices?

Since the main distribution was received by means of respiratory protection in case of a fire or a chemical accident for rescuers, we will consider this issue from already known positions. What is their difference? Suppose a firefighter needs to give an answer. So, if you try to dive under water with his respiratory protection kit, then the water will put pressure on the reducer valve. The deeper, the stronger.

It is considered safe to dive to three meters. Then there will be problems with the reducer valve - it will not open, which will prevent air from flowing.

But to stay in space, having only a cylinder of compressed air like firefighters, is quite possible. True, high-quality sealing is not ensured, moreover, the air supply is limited - therefore, it is not recommended for this purpose.

How are they similar?

Initially, the rather high price should be noted. A high-quality kit costs in the range from 40 to 80 thousand rubles, although relatively cheap devices are sold, the task of which is to give a small gain in time for people who do not take risks on an ongoing basis.

It is also common for the device itself to be assigned to several people. But the mask is for only one person. This is done for sanitary and hygienic reasons - in case someone has herpes.

It should also be noted that the weight is quite significant, which is measured in kilograms. After several hours of movement in them, back pain occurs.

The principle of operation in devices is the same. Numerical parameters vary, which can affect both the timing and the size of the apparatus. So, a cylinder with compressed air can be designed for 10-15 minutes, or for several hours.

We will devote time to the representative of these remedies

So far, we have considered conditionally generalized apparatuses. Now let's look at specific representatives.

You can start with AP-2000 (Breathing Apparatus). It is designed to protect eyesight and respiratory organs from exposure to hazardous smoky and toxic environments during fire fighting and emergency response. It can also be used to evacuate an injured person from a dangerous area in which an environment unsuitable for breathing is observed.

AP-2000 is an insulating tank apparatus. The air supply is stored in a compressed state in cylinders. In this case, the working pressure ranges from 1 MPa to 29.4 MPa, or, in other words, from 10 kgf/cm 2 to 300 kgf/cm 2 . A full-fledged panoramic mask of the device allows you to maintain excess pressure for pulmonary ventilation. This indicator can reach a value of 85 liters per minute.

Operating temperature range - from -40 to +60 degrees Celsius. Excessive pressure in the undermask space at zero air flow is maintained at 300±100 Pascals, which for clarity is equivalent to 30±10 millimeters of water column or 0.225 mercury.

The duration of the protective action is affected by the severity of the work performed, as well as temperature. So, for example, when spending 30 l / min and 25 degrees Celsius, you can perform actions in the device for 60-80 minutes (depending on the specific configuration). Whereas at minus 40 this figure will be only 45-60.

It should be noted that this is not the best copy that is on the market. For example, there is a breathing apparatus with compressed air AP "Omega", which was built taking into account the wishes of those people who operated the AP-2000. It has increased safety, comfort, as well as some additional features. Let's look at it in more detail.

What is the device of the breathing apparatus AP "Omega"?

It is made up of these parts:

1. Suspension system and light panel. Made of composite materials, comfortable, have an ergonomic surface profile to ensure maximum comfort for the user. The suspension system provides for the presence of soft shoulder straps and a comfortable belt.
2. Hoses. They have high frost, oil and petrol resistance, are characterized by high strength, and can also withstand the effects of surfactants. The hoses are designed in such a way as to exclude the possibility of breakage during operation, and also provide maximum safety during active work. The hoses have tees, which are equipped with two quick couplings. They are used for the main mask and also for the rescue device.
3. Lung machine AP-98-7KM. This miniature servo-driven device is made of high-strength plastic. It has a bypass, as well as an overpressure off button. It is attached to the side of the mask, so it does not interfere with the tilt of the head. To enable / disable the bypass, you only need to turn the handwheel on the body, which allows you to quickly and practically without occupying your hands to perform manipulations.
4. Lung machine AP-2000. Made from high strength polycarbonate. There is a multifunctional button on the case for turning on additional air supply / turning off excess pressure (aka bypass).
5. Lung machine AP "Delta". A small design that does not interfere with the tilt and turn of the head. There are two options for bypass operation. Can work automatically or manually.

What else?

We have covered the first part of the list. The second one looks like this:

1. Mask PM-2000. Designed specifically for breathing apparatus of the AP series. Among the advantages, one should recall the increased ergonomics and the quality of the material used.
2. Delta mask. It was developed by order of the Ministry of Emergency Situations of the Russian Federation. Suitable for any type of breathing apparatus with compressed air, which has excess pressure in the mask space. It has low inhalation and exhalation resistance. The design allows the air flow to evenly blow over the sight glass, which eliminates its freezing and fogging. This allows you to use the mask for a wide range of temperatures - from -50 to +60 degrees Celsius. You can also install a communication device in it.
3. Mask "PANA POWER". It is panoramic. Side connection of the lung machine is provided. It is possible to use it together with a welding shield.
4. Alarm device with pressure gauge. It is on the shoulder strap and has a swivel joint.
5. Reducer. A simple and reliable device for which a built-in valve is provided. It provides a stable reduced pressure for the entire service life of the device. Additional adjustments during operation are not required.
6. High pressure cylinders and valves. As part of the device, two types of tanks are used: steel (Russia or Italy) and metal-composite (Russian Federation or USA). For valves, a vertical and horizontal arrangement of the flywheel is provided. There are several options for their execution: with a shut-off valve (prevents the occurrence of a jet stream when breaking off); with a membrane-type safety device (protects the cylinder from explosion when the pressure rises when the cylinder is heated, etc.); both options.

Let's say a word about maintenance

This is practically considered breathing apparatus with compressed air. It remains only to pay attention to how to care for these devices. After all, timely maintenance of breathing apparatus with compressed air is a guarantee of their constant readiness and high reliability during operation. Which, accordingly, allows you to ensure safety for life and health. In order for the devices to function well, it is necessary to perform a certain set of organizational and technical measures and work. Depending on their purpose and nature, two groups are distinguished:

1. Maintenance system. Includes work that is aimed at maintaining the device in a usable condition.
2. Repair system. Includes work aimed at restoring the lost functional suitability of parts and assemblies.

A test is carried out to determine what is needed. There are several types of it:

1. It is carried out in order to maintain the device in good condition.
2. Scheduled inspection to make sure that all parts and mechanisms work as they should.
3. Disinfection, replacement of oxygen cylinders and the like.

All these actions allow you to keep the compressed air apparatus ready for operation.

A compressed air breathing apparatus is a self-contained insulating reservoir apparatus in which the supply of air is stored in cylinders in a compressed state. The respiratory apparatus operates according to an open breathing scheme, in which air is taken from the cylinders for inhalation, and exhalation is made into the atmosphere (Fig. 3.4).

Compressed air breathing apparatus is designed to protect the respiratory organs and eyesight of firefighters from the harmful effects of an unbreathable environment when extinguishing fires and performing emergency rescue operations.

The air supply system provides the person working in the device with a pulsed air supply. The volume of each portion of air depends on the frequency of breathing and the magnitude of the rarefaction during inspiration.

The air supply system of the apparatus consists of a lung machine and a reducer; it can be single-stage, gearless and two-stage. A two-stage air supply system can be made of one structural element that combines a gearbox and a lung machine, or two separate ones.

Breathing apparatus, depending on the climatic version, are divided into breathing apparatus general purpose, designed for use at ambient temperatures from -40 to +60 ° C, relative humidity up to 95%, and special

Rice. 3.4.

values, designed for use at ambient temperatures from -50 to +60 ° C and relative humidity up to 95%.

The respiratory apparatus must be able to work in breathing modes characterized by the performance of loads: from relative rest (pulmonary ventilation 12.5 dm 3 /min) to very hard work (pulmonary ventilation 100 dm 3 /min), at an ambient temperature of -40 to + 60 °C, as well as ensure operability after being in an environment with a temperature of 200 °C for 60 s. The breathing apparatus includes:

• - Breathe-helping machine;
• - rescue device (if any);
• - spare parts kit;
• - operational documentation for DAVS (operating manual and passport);
• - operational documentation for the cylinder (operating manual and passport);
• - instructions for use of the front part.

The generally accepted working pressure in domestic and foreign

DAWP is 29.4 MPa.

The shape and overall dimensions of the breathing apparatus must correspond to the physique of a person, be combined with protective clothing, a helmet and equipment of a gas and smoke protector, provide convenience when performing all types of work on a fire (including when moving through narrow hatches and manholes with a diameter of 800 ± 50 mm, crawling, on all fours, etc.).

The breathing apparatus must be designed in such a way that it is possible to put it on after turning it on, as well as to remove and move the breathing apparatus without turning it off when moving through tight spaces.

The reduced center of mass of the breathing apparatus should be no further than 30 mm from the sagittal plane of the person. The sagittal plane is a conditional line that symmetrically divides the human body longitudinally into the right and left halves.

The total capacity of the balloon (with pulmonary ventilation of 30 l/min) must provide a conditional time of protective action (PVZD) of at least 60 minutes, and the mass of DASA should be no more than 16.0 kg with PVZD equal to 60 min and not more than 18.0 kg at HPV equal to 120 min.

The main technical characteristics of breathing apparatus with compressed air are given in Table. 3.4.

The composition of DAVS (see Fig. 3.4) includes: a frame / or a back with a suspension system consisting of shoulder, end and waist belts with buckles for adjusting and fixing the breathing apparatus on the human body; balloon with valve 2 , reducer with safety valve 3 , manifold 4, connector 5, lung machine 7 with air hose 6, front part with intercom and exhalation valve 8, capillary tube 9 with buzzer, pressure gauge with high pressure hose 10, rescue device 11, spacer 2.

In modern devices, in addition, the following are used: a shut-off device for the pressure gauge line; rescue device connected to a breathing apparatus; fitting for connecting a rescue device or an artificial lung ventilation device; fitting for quick refueling of cylinders with air; a safety device located on a valve or a cylinder to prevent an increase in pressure in the cylinder above 35.0 MPa; light and vibration signaling devices, emergency gear, computer.

Suspension system of the respiratory apparatus - a component of the apparatus, consisting of a backrest, a system of belts (shoulder and waist) with buckles for adjusting and fixing the respiratory apparatus on the human body.

The suspension system prevents the firefighter from being exposed to the heated or cooled surface of the cylinder. It allows the firefighter to put on the breathing apparatus and adjust its fastening quickly, simply and without assistance. The system of breathing apparatus belts is supplied with devices for adjusting their length and degree of tension. All devices for adjusting the position

Rice. 3.5. Breathing apparatus PTS "Profi": but- general form; b- main parts

breathing apparatus (buckles, carabiners, fasteners, etc.) are made in such a way that the belts are firmly fixed after adjustment. The adjustment of the suspension system belts should not be disturbed during the apparatus change.

The suspension system of the breathing apparatus (Fig. 3.6) consists of a plastic back /; belt systems: shoulder (2), end (2), fastened to the back with buckles 4, belt (5) with a quick-release adjustable buckle.

Lodgements 6, 8 serve as a support for the balloon. The balloon is fixed with a balloon strap 7 with a special buckle.

Parameter		AP-2000 (AP "Omega")
Number of cylinders, pcs.
Cylinder capacity, l
Working pressure in the cylinder, MPa (kgf/cm2)
Reduced pressure at zero flow, MPa (kgf/cm2)	0,55...0,75 (5,5...7,5)	0,5...0,9 (5...9)	0,5...0,9 (5...9)
Activation pressure of the safety valve of the reducer, MPa (kgf/cm2)	1,2...1,4 (12...14)	1,1-1,8 (11... 18)	1,1 .1,8 (11...18)
The conditional time of the protective action of the apparatus during pulmonary ventilation is 30 dm3 / min, min, not less than			At a temperature: 25 °С - 60 min, 50 °С - 42 min
Actual inspiratory breathing resistance with pulmonary ventilation 30 dm3/min, min, Pa (mm water column), no more	300...350 (30...35)		350...450 (35...45)
Excessive pressure in the submask space at zero air flow, Pa (mm w.c.)	300...450 (30...45)	200...400 (20...40)	200...400 (20...40)
Alarm device actuation pressure, MPa (kgf/cm2)	5,3...6,7 (63...67)	5,5...6,8 (55...68)	4,9...6,3(49...63)
Overall dimensions, mm, no more	700 x 320 x 220
Weight of equipped vehicle (without rescue device), kg, no more

Table 3.4

Main technical characteristics of domestic DAS

	PST "Standard"	PTS "Profi"
0,55...1,10 (5,5...11,0)	0,7...0,85 (7...8,5)	0,7...0,85 (7...8,5)	0,6...0,9 (6...9)	0,7...0,85 (7...8,5)
1,2...2,2 (12...22)	1,2...1,4 (12...14)	1,2...2,0 (12...20)		1,2...1,4 (12...14)
350...450 (35...45)
150...350 (15...35)	420...460 (42...46)	300...450 (30...45)		420...460 (42...46)
5,0...6,0 (50...60)	5,0...6,0 (50...60)	5,0...6,2 (50...62)	290...400 (29...40)	5,0...6,0(50...60)

Rice. 3.6.

The cylinder is designed to store the working supply of compressed air. Depending on the model of the apparatus, metal, metal-composite cylinders can be used (Table 3.5).

Cylinders have a cylindrical shape with hemispherical or semi-elliptical bottoms (shells).

A conical or metric thread is cut in the neck, along which a shut-off valve is screwed into the cylinder. On the cylindrical part of the cylinder, the inscription "AIR 29.4 MPa" is applied.

The valve (Fig. 3.7) consists of a body /, tube 2 , valve 3 with insert, breadcrumbs 4 , spindle 5, gland nuts 6, handwheel 7, springs 8, nuts 9 and plugs 10.

The cylinder valve is made in such a way that it is impossible to completely unscrew its spindle, eliminating the possibility of its accidental closing during operation. It must maintain tightness in both the "Open" and "Closed" positions. The valve-cylinder connection is sealed.

The cylinder valve withstands at least 3000 opening and closing cycles. The valve fitting for connection to the reducer uses a 5/8 internal pipe thread.

The tightness of the valve is ensured by washers 11 And 12. washers 12 And 13 reduce friction between the spindle shoulder, handwheel end and gland nut ends when the handwheel is rotated.

The tightness of the valve at the junction with the cylinder with a conical thread is ensured by a fluoroplastic sealing material (FUM-2), with a metric thread - by a rubber O-ring 14.

Specifications of Air Cylinders

Designation	Cylinder capacity, l, not less than	Mass of a cylinder with a valve, kg, no more	Overall dimensions of a cylinder with a valve, mm (diameter x height)	Balloon material
				Steel
TU 14-4-903-80
				metal composite; liner - stainless steel
				Metal composite with aluminum liner
				Metal o composite with steel liner
				Lightweight metal composite with aluminum liner

BK-U-ZOOA-U
SUPER ULTRA
SUPER PREMIUM

Rice. 3.7.

but - with tapered thread W19.2; b - with cylindrical thread M18 x 1.5

When the handwheel is rotated clockwise, the valve, moving along the thread in the valve body, is pressed by the insert against the seat and closes the channel through which air enters the breathing apparatus from the cylinder. When the handwheel is rotated counterclockwise, the valve moves away from the seat and opens the channel.

The collector (Fig. 3.8) is designed to connect two cylinders of the apparatus to the reducer. It consists of a body / in which fittings are mounted 2. The manifold is connected to the cylinder valves with couplings 3. The tightness of the joints is ensured by sealing rings 4 and 5.

Rice. 3.8.

The reducer in breathing apparatus performs two functions: it reduces the high air pressure to an intermediate set value

and provides a constant supply of air and pressure after the reducer within the specified limits with a significant change in pressure in the cylinder. The most widespread are three types of gearboxes: leverless direct and reverse action and lever direct action.

In direct acting gearboxes, high pressure air tends to open the reducer valve, in reverse acting gearboxes it closes it. A leverless gearbox is simpler in design, but a lever gearbox has a more stable outlet pressure adjustment.

In recent years, piston reducers have been used in breathing apparatus, i.e. gears with balanced piston. The advantage of such a gearbox is that it is highly reliable as it has only one moving part. The operation of the piston reducer is carried out in such a way that the pressure ratio at the outlet of the reducer is usually 10:1, i.e. if the pressure in the cylinder is from 20.0 to 2.0 MPa, then the reducer supplies air at a constant intermediate pressure of 2.0 MPa. When the cylinder pressure drops below this intermediate pressure, the valve remains open permanently and the breathing apparatus operates as a single stage until the air in the cylinder is depleted.

The first stage of the air supply device is a reducer. As shown by the comparative tests of the devices, the secondary pressure created by the reducer should be as constant as possible, independent of the pressure in the cylinder, and be 0.5 MPa. The throughput of the pressure reducing valve must fully and under any kind of load provide two working people with air without increasing breathing resistance during inhalation.

In the steady state of operation of the gearbox, its valve is in balance under the action of the elastic force of the control spring, which tends to open the valve, and the pressure of the reduced air on the membrane, the elastic force of the locking spring and the air pressure from the cylinder, which tend to close the valve.

The reducer (Fig. 3.9) of a piston, balanced type is designed to convert high air pressure in the cylinder to a constant reduced pressure in the range of 0.7 ... 0.85 MPa. It consists of a body 7 with an eyelet 2 for attaching the gearbox to the apparatus frame, inserts 3 with sealing rings 4 and 5, pressure reducing valve seats including body 6 and insert 7, pressure reducing valve 8 , on which with a nut 9 and washers 10 fixed piston 77 with rubber o-ring 12, working springs 13 And 14, adjusting nuts 15, the position of which in the housing is fixed with a screw 76.

A lining 77 is put on the gearbox housing to prevent contamination. The gearbox housing has a fitting 18 s sealing ring 79 and screw 20 for connecting the capillary and fitting 21

for connecting a low pressure connector or hose. The fitting is screwed into the gearbox housing 22 with nut 23 for connection to the cylinder valve. A filter is installed in the nozzle 24, fixed by screw 25. The tightness of the connection of the fitting with the body is ensured by the sealing ring 26. The tightness of the connection of the cylinder valve with the reducer is ensured by the sealing ring 27.

The design of the gearbox provides a safety valve, which consists of a valve seat 28, valve 29, springs 30, guide 31 and lock nuts 32, fixing the position of the guide. The valve seat is screwed into the reducer piston. The tightness of the connection is ensured by the sealing ring 33.

The reducer works as follows. In the absence of air pressure in the reducer system, the piston 11 under the action of springs 13 And 14 moves with the pressure reducing valve 8, removing its conical part from insert 7.

When the cylinder valve is open, high pressure air enters through the filter 25 by fitting 22 into the cavity of the gearbox and creates a pressure under the piston, the value of which depends on the degree of compression of the springs. In this case, the piston, together with the reducing valve, is mixed, compressing the springs until a balance is established between the air pressure on the piston and the spring compression force and the gap between the insert and the conical part of the reducing valve is closed.

When you inhale, the pressure under the piston decreases, the piston with the pressure reducing valve will mix under the action of the springs, creating a gap

between the insert and the conical part of the pressure reducing valve, ensuring the flow of air under the piston and further into the lung machine. Nut rotation 15 it is possible to change the degree of compression of the springs, and, consequently, the pressure in the cavity of the gearbox, at which an equilibrium occurs between the compression force of the springs and the air pressure on the piston.

The safety valve of the reducer is designed to protect against the destruction of the low pressure line in case of failure of the reducer.

The safety valve works as follows. During normal operation of the reducer and reduced pressure within the specified limits, the valve insert 29 spring force 30 pressed against the valve seat 28. When the reduced pressure in the reducer cavity increases as a result of its malfunction, the valve, overcoming the resistance of the spring, moves away from the seat, and the air from the reducer cavity escapes into the atmosphere.

When rotating the guide 31 the degree of compression of the spring changes and, accordingly, the amount of pressure at which the safety valve operates. The gearbox adjusted by the manufacturer must be sealed to prevent unauthorized access to it.

The value of the reduced pressure must be maintained for at least three years from the date of adjustment and verification.

The safety valve must prevent the supply of high pressure air to parts operating at reduced pressure in the event of a gearbox failure.

The adapter (fig. 3.10) is intended for connection to the reducer of the lung governed demand valve and rescue device. It consists of a triple 1 and connector 2, interconnected by a hose 4, which is fixed on fittings with caps 5. The tightness of the connection between the adapter and the gearbox is ensured by a sealing ring 6. In connector housing 3 a bushing 7 is screwed in, on which the assembly for fixing the fitting of the rescue device is mounted, consisting of a clip 8, balls 9, bushings 10, springs 11, corps 12, sealing rings 13 and valve 14.

9 17 11 12 3 18 16 13 2 5 4 1

When connected to the connector, the end of the fitting of the rescue device, resting against the cuff 17 and overcoming the resistance of the spring 11, diverts valve 14 with sealing ring 13 from the saddle 15 and provides air supply from the reducer to the rescue device. The annular protrusion of the fitting at the same time displaces the sleeve inside the connector 10 ; while the balls 9, out of contact with the sleeve 10, enter the annular groove of the fitting of the rescue device. Released Clip 8 under the influence of a spring 19 moves and fixes the balls in the annular groove of the fitting of the rescue device, thus ensuring the necessary reliability of the connection between the fitting and the connector.

To disconnect the hose fitting of the rescue device, simultaneously press the hose union of the rescue device and move the clip. In this case, the fitting will be pushed out of the connector by the force of the spring. 11, and the valve will close.

The lung machine (Fig. 3.11) is the second stage of reduction of the respiratory apparatus. It is designed to automatically supply air for the user's breathing and maintain excess pressure in the undermask space. Lung machines can use valves of direct (air pressure under the valve) and reverse (air pressure on the valve) action.

Rice. 3.11.

The lung governed demand valve consists of a body / with a nut 2, valve seats with sealing ring 4 and locknut 5, shield 6, fixed with screw 7. Lever 9 with springs is installed in cover # 10, 11. Retainer 12 made as a single unit with the cover. Lid with valve body and membrane 13 hermetically connected with a clamp 14 with a screw 15 and nuts 16. The valve seat consists of a lever 17, fixed on the axis 18, flange 19, valve 20, springs 21 and washers 22, secured with a retaining ring 23.

The lung machine works as follows. valve in rest position 20 pinned to the saddle 3 spring 21, membrane 13 fixed with a lever 9 on the latch 12.

At the first breath, a vacuum is created in the submembrane cavity, under the action of which the membrane with the lever breaks off the latch and, bending, acts through the lever 17 on the valve 20, which leads to its distortion. Air from the reducer enters the resulting gap between the seat and the valve. Spring 10, acting through the lever on the membrane and the valve, it creates and maintains a predetermined excess pressure in the submembrane cavity. In this case, the pressure on the membrane of the air coming from the reducer increases until it balances the force of the overpressure spring. At this moment, the valve is pressed against the seat and blocks the air flow from the gearbox.

The lung machine and the additional air supply device are switched on by pressing the control lever in the “On” direction.

The lung machine is switched off by pressing the control lever in the "Off" direction.

The device may include a rescue device.

The rescue device consists of an approximately two-meter hose, at one end of which a bracket is attached for connection (for example, bayanette) with a T-shaped connector. A lung machine is connected to the other end of the hose. As the front part, a helmet-mask or an artificial lung ventilation device is used.

The breathing air for the firefighter and the victim comes from the same breathing apparatus.

When working in a breathing apparatus, the T-shaped connector can be used to connect to an external source of compressed air, carry out rescue operations, evacuate people from a smoky area and provide the worker with air in hard-to-reach places. The rescue device uses a lung machine without excess pressure.

Connections for connecting the lung machine of the main front part (if any) and the rescue device must be quick-disconnect (of the “Euro-coupling” type), easily accessible, and not interfere with work. Spontaneous shutdown of the lung machine and rescue device must be excluded. Free connectors must have protective caps.

The front part (mask) (Fig. 3.12) is designed to protect the respiratory and vision organs from the effects of a toxic and smoky environment and connect the human respiratory tract with the lung machine.

Rice. 3.12.

The mask consists of 7 body with glass 2, fixed with half-rings 3 screws 4 with nuts 5, intercom 6, fixed with clamp 7, and valve box 8, into which the lung machine is screwed. The valve box is attached to the body with a clamp 9 with screw 10. The tightness of the connection between the lung machine and the valve box is provided by a sealing ring. An exhalation valve is installed in the valve box 13 with hard disk 14, overpressure spring 15, saddle 16 and lid 17.

The mask is attached to the head with a headband. 18, consisting of interconnected straps: frontal 19, two temporal 20 and two occipital 21, buckled to the body 22 And 23.

mask holder 24 with inhalation valves 25 attached to the mask body with the help of the intercom body and the bracket 26, and to the valve box - a cover 27.

The headband is used to fix the mask on the user's head. To ensure the fit of the mask to size, the headband straps have serrated protrusions that lock into the body buckles. Buckles 22, 23 allow quick adjustment of the mask directly on the head.

To wear the mask around the neck, a neck strap is attached to the lower buckles of the front part. 28.

When inhaling, air from the submembrane cavity of the lung machine enters the cavity under the mask and through the inhalation valves - into the mask. In this case, the panoramic glass of the mask is blown, which eliminates its fogging.

When exhaling, the inspiratory valves close, preventing exhaled air from reaching the mask glass. The exhaled air from the undermask space is released into the atmosphere through the exhalation valve. The spring compresses the exhalation valve to the seat with a force that allows maintaining a predetermined overpressure in the undermask space of the mask.

The intercom provides the transmission of the user's speech when the mask is worn on the face and consists of a body 29, pressure ring 30, membranes 31 and nuts 32.

The capillary tube is used to connect a signaling device with a pressure gauge to the reducer and consists of two fittings connected by a high-pressure spiral tube soldered into them.

An alarm device (Fig. 3.13) is a device designed to give a working sound signal that the main supply of air in the breathing apparatus has been used up and only a reserve reserve remains.

To control the consumption of compressed air when working in breathing apparatus, pressure gauges are used, both permanently located on cylinders (ASV-2) and remote, mounted on a shoulder strap.

Rice. 3.13.

To signal the decrease in air pressure in the cylinders of the apparatus to a predetermined value, minimum pressure indicators are used.

The principle of operation of indicators is based on the interaction of two forces - the air pressure force in the cylinders and the spring force opposing it. The pointer is triggered when the gas pressure force becomes less than the spring force. In breathing apparatus, three designs of indicators are used: rod, physiological and sound.

Stock pointer The device is installed directly on the gearbox housing, on the hose, on the shoulder strap. When controlling pressure, the position of the stem is felt by hand.

The pointer is cocked by pressing the button of the rod before opening the valve of the device. When the pressure in the cylinders drops to the set minimum, the rod returns to its original position.

The physiological indicator, or the reserve air supply valve, in various designs is a locking device with a movable locking part. The locking part has a spring to hold the valve against the seat. When the pressure in the cylinders is above the minimum, the spring is compressed and the valve is raised above the seat. At the same time, the air freely passes through the ma-

hystrals. When the pressure drops to the minimum, the valve, under the action of a spring, falls on the seat and closes the passage. A sharply occurring lack of air for breathing serves as a physiological signal about the consumption of air to the minimum (reserve) pressure.

buzzer most common in compressed air breathing apparatus. It is mounted in the reducer housing or combined with a pressure gauge on the high pressure line. The design principle of the work is similar to the stock indicator. When the air pressure in the cylinders drops, the rod moves, and the air supply to the whistle opens, which makes a characteristic sound.

The operation of the sound signal according to standards, both European and domestic, should be at the level of 5 MPa or 20-25% of the air supply in the equipped cylinder. The duration of the signal must be at least 60 s. The volume of the sound should be at least 10 dB higher than that of a fire. The sound must be easily distinguishable from other sounds without compromising other sensitive or important operating functions.

The signaling device (Fig. 3.13) consists of a housing /, pressure gauge 2 with cladding 3 and gasket 4, bushings 5, bushings 6 with sealing ring 7, whistle 8 with locknut 9, casing 10, sealing rings 11, shtochka 12, bushings 13 with sealing ring 14, nuts 15 with locknut 16, springs 17, plugs 18 with sealing ring 19, sealing rings 20 and nuts 21.

The signaling device works as follows. When the cylinder valve is open, high-pressure air enters through the capillary into the Aik cavity to the pressure gauge. The manometer shows the amount of air pressure in the cylinder. From cavity A, high-pressure air through a radial hole in the sleeve 13 enters the cavity B. The rod under the action of high air pressure moves to the stop in the sleeve 5, compressing the spring. In this case, both outlets of the oblique hole of the rod are located behind the sealing ring 7.

As the pressure in the cylinder decreases and, accordingly, the pressure on the stem shank, the spring will move the stem to the nut 15. When the exit of the oblique hole in the rod closest to the sealing ring 7 is mixed behind the sealing ring, air under reduced pressure through the channel in the housing 1, the oblique hole in the rod and the hole in the sleeve 5 enters the whistle, causing a steady sound signal. With a further drop in air pressure, both outlets of the oblique hole in the rod move beyond the sealing ring, and the air supply to the whistle stops.

Adjustment of the pressure of the alarm device is carried out by moving the whistle along the thread in the body. In this case, the sleeve 5 is moved with the sleeve 6 and O-ring 7.

Security questions for chapter 3

• 1. Name the device of the breathing apparatus with compressed air.
• 2. Tell us about the purpose and technical characteristics of domestic DAS.
• 3. Describe the principle of operation of AHSA.
• 4. Appointment of hose breathing apparatus.

Questions for self-study

Study the device and principle of operation of a breathing apparatus with compressed air.

• Complete with rescue device. Depending on modification. Cylinder capacity, overall dimensions and weight of the equipped apparatus are determined depending on the model.

BREATHING APPARATUS WITH COMPRESSED OXYGEN (DASK)

General device and principle of operation of DASK

Compressed oxygen breathing apparatus (CASC) is a regenerative apparatus in which a gas respiratory mixture is created by regenerating the exhaled gas mixture by absorbing carbon dioxide from it by a chemical substance and adding oxygen from a small-capacity cylinder present in the apparatus, after which the regenerated gas respiratory mixture enters the inhale.

DASC should be efficient in breathing modes characterized by the performance of loads: from relative rest (pulmonary ventilation 12.5 dm 3 /min) to very hard work (pulmonary ventilation 85-100 dm 3 /min) at an ambient temperature of -40 to + 60 °C, and also remain operational after being in an environment with a temperature of 200 ± 20 °C for 60 ± 5 s.

Rice. 2.1.

Rated protective action time (hereinafter referred to as RTA) is the period during which the protective ability of the device is maintained when tested on a human external respiration simulator in the mode of performing work of medium severity (pulmonary ventilation 30 dm 3 /min) and ambient temperature (25 ± 2) °C. In the mode of performing work of medium severity (pulmonary ventilation 30 dm 3 /min) at an ambient temperature of (25 ± 1) ° C, the HVD DASC for firefighters should be at least 4 hours.

The actual time of the protective action is the period during which the protective ability of the apparatus is maintained when tested on a human external respiration simulator in the mode: from moderate work to very hard work (pulmonary ventilation 85 dm 3 /min) at an ambient temperature of -40 °С to +60 °С.

Modern DASC (Fig. 2.2) consists of air and oxygen supply systems. The air duct system includes a front part 7, a moisture collector 2, breathing hoses 3 And 4, breathing valves 5 and 6, regenerative cartridge 7, cooler 8, breathing bag 9 and overflow valve 10. The oxygen supply system includes a control device (pressure gauge) 77, showing the supply of oxygen in the apparatus, devices for additional (bypass) 12 and main oxygen supply 13, locking device 14 and oxygen storage tank 15.

with compressed oxygen

The front part, which is used as a mask, serves to connect the airway system of the device to the human respiratory system. The airway system, together with the lungs, forms a single closed system isolated from the environment. In this closed system, when breathing, a certain volume of air makes a variable movement in direction between the lungs and the breathing bag. Thanks to the valves, this movement takes place in a closed circulation circuit: the exhaled air passes into the breathing bag along the exhalation branch (front part 7, exhalation hose 3, exhalation valve 5, regenerative cartridge 7), and the inhaled air returns to the lungs along the inspiratory branch (refrigerator 8, inhalation valve 6, inhalation hose 4, front part 7). This pattern of air movement is called circular.

Exhaled air is regenerated in the airway system, i.e. restoration of the gas composition that the inhaled air had before entering the lungs. The regeneration process consists of two phases: cleaning the exhaled air from excess carbon dioxide and adding oxygen to it.

The first phase of air regeneration takes place in the regenerative cartridge. As a result of the chemisorption reaction, the exhaled air is cleaned in the regenerative cartridge from excess carbon dioxide by the sorbent. Two types of carbon dioxide chemisorbents from exhaled air are used in DASC: calcareous based on calcium hydroxide Ca(OH) 2 and alkaline based on sodium hydroxide NaOH. In our country, a chemical lime absorber HP-I is used. The carbon dioxide absorption reaction is exothermic, so heated air enters the breathing bag from the cartridge. Depending on the type of sorbent, the air passing through the regenerative cartridge is either dried or humidified. In the latter case, during its further movement, condensate forms in the elements of the air duct system.

The second phase of air regeneration takes place in the breathing bag, where oxygen is supplied from the oxygen supply system in a volume slightly larger than it is consumed by a person, and determined by the method of oxygen supply of this type of DASC.

In the DASK air duct system, the regenerated air is also conditioned, which consists in bringing its temperature and humidity parameters to a level suitable for human inhalation. Usually air conditioning is reduced to its cooling.

The respiratory bag performs a number of functions and is an elastic container for receiving air exhaled from the lungs, which then enters for inspiration. It is made of rubber or gas-tight rubberized fabric. In order to ensure deep breathing during heavy physical exertion and separate deep exhalations, the bag has a useful capacity of at least 4.5 liters. In the breathing bag, oxygen is added to the air leaving the regenerative cartridge. The breathing bag is also a collection of condensate (if any); sorbent dust is retained in it, which in a small amount can penetrate from the regenerative cartridge; the primary cooling of the hot air coming from the cartridge occurs due to heat transfer through the bag walls to the environment. The breathing bag controls the operation of the excess valve and lung machine. This control can be direct or indirect. With direct control, the wall of the breathing bag directly or through a mechanical transmission acts on the excess valve or lung machine valve. With indirect control, these valves open from the impact on their own sensing elements (for example, membranes) of pressure or vacuum created in the inhalation bag when it is filled or emptied.

The excess valve serves to remove excess gas-air mixture from the airway system and operates at the end of expiration. In the event that the operation of the excess valve is controlled indirectly, there is a risk of losing part of the gas-air mixture from the breathing apparatus through the valve as a result of accidental pressure on the wall of the breathing bag. To prevent this, the bag is placed in a rigid housing.

Refrigerator is used to reduce the temperature of inhaled air. Air coolers are known, the action of which is based on the transfer of heat through their walls to the environment. Refrigerators with a refrigerant are more efficient, the operation of which is based on the use of the latent heat of phase transformation. Water ice, sodium phosphate and other substances are used as a melting refrigerant, ammonia, freon, etc. are used as evaporating into the atmosphere. Carbon dioxide (dry) ice is also used, which immediately turns from a solid state into a gaseous one. There are refrigerators equipped with refrigerant only when operating at elevated ambient temperatures.

The schematic diagram shown in fig. 2.2 is general for all groups and varieties of modern DASC.

In various models of DASC, three schemes of air circulation in the air duct system are used: circular (see Fig. 2.2), pendulum and semi-pendulum.

Main advantage circular scheme - the minimum volume of harmful space, which includes, in addition to the volume of the front part, only a small volume of air ducts at the junction of the branches of inhalation and exhalation.

Pendulum scheme differs from the circular one in that in it the branches of inhalation and exhalation are combined, and the air through the same channel moves alternately (like a pendulum) from the lungs to the breathing bag, and then in the opposite direction. With regard to the circular circuit (see Fig. 2.2), this means that it does not have breathing valves 5 and 6, the hose 4 and refrigerator 8 (in some devices, the refrigerator is placed between the regenerative cartridge and the front part). The pendulum circulation scheme is used mainly in devices with a short protective action time (in self-rescuers) in order to simplify the design of the device. The second reason for using such a scheme is to improve the sorption of carbon dioxide in the regenerative cartridge and use for this additional absorption during the secondary passage of air through the cartridge.

The pendulum air circulation scheme is distinguished by an increased volume of harmful space, which, in addition to the front part, includes a breathing hose, the upper air cavity of the regenerative cartridge (above the sorbent), and the air space between the spent sorbent grains in its upper (frontal) layer. With an increase in the height of the spent sorbent layer, the volume of this part of the harmful space increases. Therefore, DASC with pendulum circulation is characterized by an increased content of carbon dioxide in the inhaled air compared to the circular scheme. In order to reduce the volume of harmful space to a minimum, the length of the breathing hose is reduced, which is possible only for devices located in the working position on the human chest.

Semi-pendulum scheme differs from the circular one in the absence of an exhalation valve 5 (see Fig. 2.2). When exhaling, air moves through the exhalation hose 3 and regenerative cartridge 7 into the breathing bag 9 in the same way as in the circular pattern. When you inhale, most of the air enters the front part 1 through the fridge 8, inhalation valve 6 and inhalation hose 4, and some of its volume passes through the regenerative cartridge 7 and the hose 3 in the opposite direction. Since the resistance of the exhalation branch containing the regenerative cartridge with the sorbent is greater than that of the inhalation branch, a smaller volume of air passes through it in the opposite direction than through the inhalation branch.

DASKs are known with a circular air circulation scheme, in which, in addition to the main breathing bag 9 (see Fig. 2.2), there is an additional bag located between the exhalation valve 5 and the regenerative cartridge 7. This bag serves to reduce the exhalation resistance due to "smoothing" peak value of the air volume flow.

At the beginning of the last century, devices with forced air circulation through a regenerative cartridge were widely used. They had two breathing bags and an injector fed with compressed oxygen from a cylinder and sucking air through a regenerative cartridge from the first bag to the second. This technical solution was due to the fact that at that time regenerative cartridges had a high resistance to air flow. Forced circulation made it possible to significantly reduce expiratory resistance. In the future, injector devices did not become widespread due to the complexity of the design, the creation of a rarefaction zone in the air duct system, which contributes to the suction of outside air into the device. The decisive argument in refusing to use injector devices was the creation of more advanced regenerative cartridges with low resistance. During the period of use of injector devices and after their abandonment, all other devices were called the obsolete term "lung-power breathing apparatus".

The refrigerator is an obligatory element of DASK. Many older models do not have it, and the air heated in the regenerative cartridge is cooled in the breathing bag and inspiratory hose. Air (or other) coolers are known, located after the regenerative cartridge, in the breathing bag, or constituting a single structural unit with it. The last modification also includes the so-called “iron bag”, or “bag inside out”, which is a sealed metal tank, which is the body of the DASK, inside which there is an elastic (rubber) bag with a neck that communicates with the atmosphere. The elastic container, into which air enters from the regenerative cartridge, in this case is the space between the walls of the reservoir and the inner bag. This technical solution is characterized by a large surface area of ​​the tank serving as an air cooler and a significant cooling efficiency. A combined breathing bag is also known, one of the walls of which is simultaneously the lid of the device's knapsack and an air cooler. Breathing bags combined with air coolers, due to the complexity of the design, not compensated by a sufficient cooling effect, are currently not widespread.

The redundant valve can be installed anywhere in the ductwork system, except for the area to which oxygen is directly supplied. However, valve opening (direct or indirect) must be controlled by the counterlung. In the event that the supply of oxygen to the air duct system significantly exceeds its consumption by a person, a large volume of gas escapes into the atmosphere through the excess valve. Therefore, it is advisable to install the specified valve before the regenerative cartridge in order to reduce the carbon dioxide load on the cartridge. The installation location of the excess and breathing valves in a particular model of the device is selected from design considerations. There are DASKs, in which, unlike the scheme shown in Fig. 2.2, breathing valves are installed at the top of the hoses at the junction box. In this case, the mass of the elements of the apparatus, which falls on the face of a person, slightly increases.

Variants and modifications of the circuit diagram of the oxygen supply system of breathing apparatus with compressed oxygen are predetermined primarily by the method of oxygen reservation implemented in this apparatus.

The air supply system of the device consists of a lung machine and a reducer, it can be single-stage, without a reducer and two-stage. The two-stage air supply system can be made of one structural element that combines the gearbox and the lung machine or separately.

The devices are produced by manufacturers in various versions.

The main nodes of DAVS, their purpose

suspension system designed to mount systems and components of the device on it.

Includes: plastic back, shoulder and end straps fastened to the back with buckles, waist belt with quick-release adjustable buckle. Lodgment which serves as a support for the cylinder. The balloon is fixed with a balloon strap with a special buckle.

Marking: trademark of the manufacturer, symbol of the device, technical specification number, serial number, month and year of manufacture.

Cylinder with valve designed to store the working supply of compressed air.

The valve consists of: body, valve, gasket, 2 rings, cover, spindle, handwheel, cover, safety diaphragm, shut-off valve, shock absorber.

Marking: cylinder designation, heat treatment stamp, quality control stamp, manufacturer's code, lot number, number of the cylinder in the lot, month and year of manufacture, year of the next survey, empty cylinder mass, working pressure, test pressure, nominal volume.

Reducer designed to convert high air pressure in a cylinder to a constant reduced pressure. The reducer has a safety valve (and also a signaling device mechanism can be structurally built into the reducer).

Includes: housing, reduced valve, piston, spring, handwheel, threaded fitting, sealing ring, cuff, safety valve, seal.

Capillary it is intended for accession to a reducer of the manometer and a sound signal.

Includes: 2 fittings connected by a high-pressure spiral tube soldered into them, inside the spiral of which the cable is also connected to the fittings, are inside 2 fittings connected and fixed by a hose using caps, sealing rings.

pressure gauge designed to control the pressure of compressed air in the cylinder, a sound signal to alert you that the air in the cylinder is running out.

Lung machine designed to automatically supply air to the user's breathing, maintain excess pressure in the undermask space, additional air supply, turn off the air supply and connect the front part to the device. The lung machine turns on at the first breath, turns off by pressing the button for additional air supply.

Includes: valve, spring, ring, diaphragm, valve seat, support, stem, button, cover.

panoramic mask designed to protect the respiratory and human vision from a toxic and smoky environment and connects the human respiratory tract with the lung machine.

Includes: housing with headband straps, panoramic glass, two half-rings, a mask holder with two inhalation valves, an intercom, a plug connection for fastening a lung governed demand valve of a spring-loaded exhalation valve.

Adapter designed to connect the main front part of the lung machine and the rescue device to the gearbox.

Includes: tee, a connector interconnected by a hose which is fixed to the fittings of the tee by caps. A bushing is screwed into the connector housing, on which the hose fitting fixing unit is mounted to save the device and consists of: clips, balls, bushings, springs, housing, sealing ring, valve.

rescue device It is designed to protect the respiratory organs and eyesight of the victim from an environment unsuitable for breathing.

Includes: helmet mask, lung machine and low pressure hose.