Linear thermal fire detectors installation. Types and arrangement of linear heat detectors

Specialists highlight a large number of types of cables. But a separate class includes a linear thermal fire detector, which is used in hardware and software systems for monitoring the state nuclear power plants. The sensitive element in such a device is located along the entire length of the cable, it can change its electrical parameters when conditions change. external environment. The sensitive elements are so visible that they can be freely fixed. Compared to other cables and sensors, such devices are not unified, so there are no uniform standards for them.

At many events there is big number fire safety problems due to their complex configurations, working conditions, temperature and other difficult features.

For example, under the condition of strong electromagnetic problems, smoke in the facility, high radiation many temperature and smoke sensors and flame detectors cannot function normally and give a signal about the presence of an accident at work. In many cases, the use of a linear fire heat detector is really justified, and in some cases there is not even a replacement for them, for example, when used on nuclear reactor.

Thermal cables can be used almost everywhere, but special efficiency can be achieved on cable routes, collectors, elevator shafts, garbage chutes, tunnels, tanks with combustible and smear components, tunnels and transport stations. With the help of a large temperature range, fire heat detectors can be used in freezers, refrigerators, elevators, hangars and some industrial events.

Since the heat cable can be used in buildings with large electromagnetic fields without degrading its performance, it can additionally be used to control the quality of heating devices (for example, generators, tomographs and transformers).

Due to the special flexibility and small diameter of the cable, the thermal fire detector helps to track the temperature in particularly hard-to-reach places. In this case, it is important that the cable is laid on the very surface of the equipment.

Instrument operation

Structurally, the thermal cable includes a twisted pair, which is made of steel wire. Each wire is twisted into a twisted pair and coated with special heat-sensitive polymers.

For this reason, the cable contains high voltage, which in case of problems with insulation leads to a short circuit.

The principle of operation of the IP thermal fire detector for fire alarm concluded that when a certain temperature regime is reached, the sensitivity to heating of the insulation is violated, and the wires are connected under the influence of internal voltage, as a result of which a short circuit occurs. In order for the thermal cable to be activated, it is enough for overheating to occur in just one area. The total line resistance changes rapidly. A special controller is responsible for the conductivity of the cable, determines the exact area of ​​its ignition, compares it with the settings and redirects the alarm signal to the bullets of the anti-protective device.

The main types of sensors

All thermal fire detectors according to the sensor reaction can be divided into maximum ones, which give a reaction to set temperature, differential, which start to work at its certain change from the set parameters, as well as maximum-differential sensors, which give a reaction to these two factors at once. All of them are contact, electronic, optical, as well as mechanical.

Mechanical sensors

Maximum thermal fire detector when monitoring the state of the device calculates the dependence of pressure on temperature environment. The sensor in the device contains a special copper tube with compressed gas. An increase in temperature indicates a change in pressure in the tube, which is indicated on the sensor itself. The measuring unit changes the incoming indicators of the detector into temperature and, if the set parameters are exceeded, they send an alarm signal to the fire panel. Such types of mechanical sensors are almost never used due to the complexity and development of more technological and modern sensors.

contact devices

Contact sensors in linear detectors are a twisted pair of steel wires that are made from temperature-sensitive polymers. The number of wires may be more than a few. The outer shell can be made from different materials, this will directly depend on the area of ​​\u200b\u200btheir use.

In the zone of fire and overheating, the cable insulation begins to melt, which provokes a short circuit. The well-designed interface module helps to determine the line resistance and the total distance to the wire short.

Electronic sensor

Unlike contact linear detectors, linear electronic sensors do not provoke a short circuit during operation of the device, they read all changes in resistance from the ambient temperature and transfer them to the control and measuring device.

The sensitive element includes a large number of sensors that are installed in a multi-core cable, through which all information passes from each element of the line. The receiving unit processes the received signals and compares them with the alarm parameters set in it. When a critical situation is detected, the device transmits an alarm signal to the fire panel.

optical sensor

Features of the operation of the optical sensor in a linear thermal fire detector are based on a change in the optical transparency of the sensor, which directly depends on the ambient temperature. For this, a fiber optic cable is used. At that moment, when the light from the laser falls on the place of ignition or overheating, part of it is immediately reflected. The processing device detects the power of the direct and reflected color, the speed of its change and the detection of the temperature in the area where the problem occurred.

Depending on the type of fiber used and the settings of the processing module, the equipment can perform many thermal sensor functions.

Most Popular Devices

The most popular and widely used thermal cables include the following models:

• Protectowire;
• Thermocable;
• "Special device";
• "Pozhtechnik";
• "Etra-special automatic".

Thermal cables from Protectowire have been on the market for over 10 years. For the past four years, manufacturers have been producing contact-type thermal cables for fire alarms.

The features of the devices and their cost do not differ much, the differences are in the cable resistance of only 1 meter, maximum length, current voltage and overall range. Depending on the purpose of using the device, you can find a better and more convenient cable for yourself.

Recently, models of thermal cables are often produced electronic type. They include a cable up to 24 centimeters long with a temperature sensor installed inside the sheath, in some models an additional sensor is built in to help detect carbon monoxide nearby. Unlike contact linear devices function in the same way as thermal ones.

Mounting Features

There are many ways to install a fire thermal linear detector. As a rule, the same requirements are imposed on a thermal cable as on a simple point thermal sensor. The installation of the fire alarm detector is carried out using special fasteners, which are included with the purchase of the device or are recommended for purchase by the manufacturer of the thermal cable. It is important to buy special fasteners, as this will help to avoid problems with cable insulation and, as a result, a false circuit. If the cable includes several pieces at once, then special terminal connectors are used.

Such a cable is installed under the ceiling or on the walls. In the place where there are some problems with laying the thermal cable, a specialized suspension cable should be used.

When laying the detector, it is important to remember about technological characteristics premises, for example, in warehouses, it is important to take into account the functioning of unloading and loading devices.

It is important to install the cable with a stretch and at a room temperature not lower than -10 degrees Celsius, but such a device will work at temperatures from -40 to +125 degrees Celsius. When installing the safety detector on flat ceilings, the distance between adjacent cables should not exceed 10.6 meters.

Manufacturer's requirements

In addition, there are special requirements from the device manufacturer. To ensure its normal functioning, it is important to comply with them. The cable should not be allowed to touch any objects, as this will prevent it from responding normally to temperature changes in the environment. Objects in close proximity to the detector can act as a heat sink, causing various malfunctions in the device.

Its safety and performance will directly depend on the high-quality installation of a fire thermal linear detector at an event. All technical means with the help of sensors built into them help to identify the source of ignition and prevent a fire in time. Technical requirements to such devices continue to increase. The emergence of new detectors that help identify areas of fire, contributes to the timely and accurate detection of a fire.

Where are the devices used?

Thermal linear fire detectors are commonly used at the following facilities:

• heated and unheated premises;
• outdoor facilities, including linearly extended ones;
• events that are characterized by a large length of the ceiling, for example, production shops, shopping malls, sports stadiums, theaters, concert halls, sewers, mines and tunnels, energy and transport facilities, including sea and river vessels.

The sensor with high sensitivity in the device can be installed in direct contact with the protective device, in hard-to-reach places and used in conditions with low or high temperature, high humidity, dustiness, and vibration.

Heat detector "Bolid"

Linear thermal fire detector "Bolid" is an optical installation, which includes a receiver and a transmitter. The device can be mounted in different corners of the building, in close proximity to the ceiling, determine the value of the distance (50-140 meters).

Modern developments of detectors include a self-monitoring system that helps to amplify the applied signal during dusting of optical devices. The cost of the heat detector Bolid is quite high (starts from 4000 rubles), but at the same time the device has a minimum number of wires, and it is also very quickly mounted.

Addressable fire detector "Bolid". This type of sensor helps to receive and transmit signals through the radio channel, the total range of the device reaches 600 meters.

Fire Thermal Linear Detector The GTSW 68 thermal cable is used to control the threshold temperature and detect the ignition source to prevent a fire at the facility. The device regulates the temperature along its entire length and can function in conjunction with MIP modules.

The thermal cable includes a cable that helps to determine the source of overheating in any area. Only one sensor is built into the detector continuous action, which is used when the conditions at the enterprise do not allow the installation of a simple sensor, and if there is a risk of explosion, the use of a thermal cable is considered the best way out.

The PHSC 155 linear fire detector is also very popular on the market. The system includes a cable that helps to identify the heat source along its entire length, it is also equipped with a special permanent sensor.

There are many types of cable products. But there is a special class among them, which is used as a fire detector in fire and security alarm systems, in hardware and software systems for monitoring the state of nuclear power plants. He received the name: linear thermal fire detector. Its sensing element is located along the entire length of the cable and is able to change its electrical parameters from changes in the external environment. They are so noticeable that they can be clearly fixed. Compared to other cables, sensors, as they are also called, are not unified, there is no standard for them.

Often, in the CIS, the term "thermal cable" is used instead of the expression "linear heat detector". This is due to the fact that for the first time it entered the Russian market under this name.

Application area

Problem fire safety many objects is difficult due to their complex configuration, working conditions, temperature conditions and many other factors. For example, in conditions of strong electromagnetic fields, high smoke, high background radiation, most temperature, smoke and flame detectors cannot respond correctly to an emergency. In many cases, the use of thermal cables is justified, and in some cases there is no alternative to them, as is the case with nuclear reactors.

Thermal cables can be used almost everywhere, but they are especially effective in cable routes, collectors, elevator shafts, garbage chutes, tunnels, air ducts, tanks with fuels and lubricants, transformer substations. Due to the wide temperature range, they can be successfully used in freezers and cold stores, elevators, warehouses, hangars, piers and many other facilities.

Since the thermal cable can be used in rooms with large electromagnetic fields without deteriorating its performance, it can also be used to directly control the heating of equipment, such as transformers, generators, tomographs.

Note!

Due to the flexibility and small diameter of the cable, it became possible to control the temperature in hard-to-reach places in installations.

In this case, it is permissible to lay the cable directly on the surface of the devices.

The principle of operation of a thermal cable for a fire alarm

Structurally, the thermal cable is a twisted pair made of steel wire. Each wire is coated with a heat sensitive polymer and then twisted together into a twisted pair.

Because of this, voltages arise in the cable, which, if the insulation is broken, lead to a short circuit.

The principle of operation of a thermal cable for a fire alarm is that when a certain temperature is reached, the heat-sensitive insulation is broken, the wires are connected under the action of internal voltage, and a short circuit occurs. For the thermal cable to operate, it is enough that overheating occurs in one place. The total line resistance changes. A special controller measures the cable conductivity, calculates the fire location, compares it with presets and sends an alarm signal to the control panel fire protection.

Types of linear sensors

Linear heat detectors (thermal cables) according to the reaction of the sensor are divided into maximum, which respond to reaching the threshold temperature, differential, which respond to a certain change in it, and maximum differential sensors that respond to both. They are mechanical, contact, electronic and optical.

• Mechanical

Such sensors use the dependence of pressure on ambient temperature as a controlled parameter. The sensor is a copper tube with compressed gas. An increase in temperature causes a change in pressure in the tube, which is recorded by the sensor. The measuring unit converts the detector readings into temperature and sends an alarm signal to the fire panel when the threshold values ​​are exceeded. It is practically not used due to the complexity and the emergence of more modern and efficient sensors.

• Contact

The sensor of such a linear detector is a twisted pair of steel wires coated with a heat-sensitive polymer. The number of wires can be more than two. The outer shell is made differently depending on the application.

In a fire or heating zone, the cable insulation melts and a short circuit occurs. The processing interface module calculates the change in line resistance and reports the distance to the fault.

• Electronic

Unlike contact linear heat detectors, linear electronic sensors up to short circuit the matter is not brought up, they fix the change in the resistance of the sensors from temperature and transmit it to the control and measuring unit. The sensing element is a set of sensors built into a multi-core cable, through which all information from each element of the line is transmitted. The receiving unit converts the received signals and compares them with the alarm parameters stored in its memory. If these limits are exceeded, the device issues an alarm to the fire panel.

• Optic

The principle of operation of the optical linear sensor is based on the change in the optical transparency of the sensor depending on the change in temperature. For this, a fiber optic cable is used. When light from a laser hits a fire, some of it is reflected. The processing device determines the power of direct and reflected light, the rate of change and calculates the value of the temperature change, and the place where it happened.

Depending on the type of optical fiber and the settings of the processing module, the device can perform all types of functions of a thermal fire detector.

TOP-5 models of thermal cable

The most common models of thermal cables for Russian market:

1. Protectowire,
2. thermocable,
3. fire technicians,
4. special device,
5. Etra-special automation.

Protectowire has been on the market for over 10 years. The first four manufacturers produce contact-type fire alarm cable.

Specifications and prices are about the same, difference in cable resistance per 1 meter, maximum allowable length, DC voltage and operating range. Depending on the requirements of the project, it is convenient to choose the best option cable.

Etra-special automation produces linear electronic type detectors. They are a cable 24 m long with temperature sensors mounted inside the braid, some models have presence sensors carbon monoxide. Unlike contact linear sensors, they work as all-mode heat detectors.

Errors during installation and connection

The same requirements are imposed on the thermal cable as on a conventional point thermal sensor with normally open contacts. Installation of a fire alarm thermal cable must be carried out with its own fasteners developed by the manufacturer or recommended by him. This is necessary to prevent damage to the cable insulation and, accordingly, false operation of the system. If the cable consists of several pieces, then special terminal connectors are used.

The cable is laid under the ceiling or along the walls. Where laying is difficult, a suspension cable is used.

The cable is laid with a snake.

When laying, it is necessary to take into account the technological features of the object. For example, in warehouses, you need to take into account the work of loading and unloading equipment.

Cable installation must be carried out with some tension at temperatures not lower than -10° C, but the system will also work in the range of -40° C + 125° C. When laying on flat ceilings, the distance between cables, according to international standards, should not be more than 10 .6 m for TH68 and TH88. For TH105, the distance should not exceed 7.5 m.

In addition, there are manufacturer's requirements. For reliable operation, all of them must be fulfilled. Touching the cable to some objects will interfere with the accurate and correct response of the system. They can play the role of a radiator, thereby introducing an error into the work.

Conclusion

Its safety and performance largely depend on the correct design and installation of the fire protection system of an object. Role technical means detection and prevention of fire, its primary sensors, increases significantly. The demands on them are increasing. The emergence of new detectors based on different principles of fire detection contributes to early and accurate fire detection.

When buying a 5000 m linear detector IP-104/IPLT ProReact Digital ТН

THERMOCABLE_MIP2I module AS A GIFT!

Linear thermal fire detector
The structure of SPIP "TERMOCABLE" includes:
Interface fire module "TERMOKABEL_ MIP2I" with indication of the exact location of fire with the function of connecting two loops of a linear thermal fire detector IP-104 ProReact Digital TH (hereinafter the module and / or abbreviation MIP2I).

The interface fire module "TERMOKABEL" MIP2I works only with the linear thermal fire detector IP-104/IPLT ProReact Digital ТН and Thermocable ProReact Digital.

The interface fire module "TERMOKABEL" MIP2I is not designed to work together with a linear thermal fire detector with a resistance of more than 100Ω/km per conductor.

The main features of the MIP2I module:

Connection of two loops of a linear thermal fireman is notified
· Two operating modes: independent and two-threshold
Independent mode provides independent control over the operation of each linear thermal fire detector connected to MIP2I, which allows you to connect the device to both linear thermal fire detectors similar in characteristics (of the same sensitivity temperature, in a shell of the same type) and linear thermal fire detectors with different characteristics .(different temperature sensitivity and different shell). At this mode operation, in the event of a fire in one of the loops, the device will give a “FIRE” signal and determine the distance to the source of ignition.
· The two-threshold mode provides joint control of two zones of the linear thermal fire announcer with a possibility of delivery of a preliminary signal about ignition and a signal "FIRE". In this mode, the signal "FIRE" is given only when two loops of the linear thermal fire detector connected to the MIP2I are triggered simultaneously.

The system for transmitting a fire notification SPIP "TERMOKABEL" is designed to determine the point of fire along the entire length of the sensitive element (linear thermal fire alarm) with the determination of the exact location of the fire and the notification of fire by giving an audible signal, as well as transmitting a text notification about the distance to the place of ignition in meters on LCD displays.

Advantages of THERMOCABLE

• Low price in rubles at a fixed price list.
• Two connection options: One or two loops
• Maximum cable length — 3000 m using interface module
• It is an analog replacement for all thermal linear fire detectors on the Russian market.
• Compatible with any fire alarm panel.
• Guaranteed sensitivity along the entire length of the cable.
• Minimum bending radius reduced to 50 mm
• Sensitivity range from +68, +78, +88,+105,+185 degrees C
• Sheaths: PVC, nylon, polypropylene and steel braid.
• It is used in an environment with aggressive factors.
• UV protection for outdoor use
• Protection against mechanical damage
• Anti-interference
• Increased level of chemical protection and protection in alkaline environments

System Composition

Interface fire module "TERMOKABEL_ MIP2I" with indication of the exact location of fire with the function of connecting two loops of a linear thermal fire detector IP-104 ProReact Digital TH (hereinafter the module and / or abbreviation MIP2I).

Supports MODBUS protocol

LCD display with indication

Two options for connecting a linear thermal fire detector: directly to MIP2I and connecting through a lead-connecting cable, which allows you to reduce the number of linear thermal fire detectors, as well as install MIP2I in any place convenient for the user. Calibration of the connecting cable is carried out automatically during the first installation of the system.
Fault monitoring of the linear thermal firefighter is notified.
Possibility of connecting one loop of a linear thermal fire detector.

Linear thermal fire detector IP-104/IPLT ProReact Digital ТН

Length of one loop up to 3000 m

Response temperature: +68С, +78С, +88С, +105С, +185С

Sheaths: PVC, Nylon (for outdoor use, resistant to aggressive environments), polypropylene (resistant to aggressive environments), steel braid (protects the linear heat detector from mechanical damage)
outdoor applications
Resistant to aggressive environments
Resistant to mechanical damage
Maintenance Free
Long term operation up to 25 years

Mounting box ТН-1000

Specifications

Application area

A typical solution for the use of a thermal cable is a room with large area or a long length, as well as hard-to-reach areas that require 100% coverage and protection, extended areas, areas with an aggressive environment. The heat detector is resistant to dust, humidity, chemicals, high and low temperatures, can be used in explosive areas, easy to install, does not require maintenance. Service life - at least 30 years.

Wiring diagram

Thermal linear fire detectors. Mounting and installation examples

THERMAL FIRE DETECTORS IN-LINE INSTALLATION AND INSTALLATION EXAMPLES

The previous issue of the Safety Algorithm magazine (2013, No. 3) presented material on linear thermal fire detectors, their purpose and principles of operation.

In this article, we will talk about the features of the installation of thermal linear out-broadcasters, about their use on complex objects, we will present several standard solutions on their installation.

Recall, just in case, what a linear thermal fire detector or a thermal cable is. This is a signal cable that responds to changes in the limiting temperature of any section along its entire length. The thermal cable is both a sensor and a cable at the same time. Any point on a linear thermal fire detector can be considered as a separate thermal sensor. The rules for installing a thermal cable are the same as for point thermal fire detectors with normally open contacts.

INSTALLATION OF THE HEAT LINEAR FIRE DETECTOR

All types of thermal cable are mounted using special fasteners. For splicing cable segments, terminal connectors and crimping devices are used. The thermal cable is mounted in continuous sections without branches and branches (like a snake). It can be placed on the ceiling of the protected room or structure or on the walls. In areas where installation is difficult, it is recommended to place the heat cable on a steel carrier cable.

Before starting the installation of a thermal cable, it is necessary to carefully plan the place of its installation. Planning is carried out on the basis of drawings of protected or controlled areas, taking into account data on the location and configuration of cables in space. Wrong installation or fastening of a linear heat detector can lead to its mechanical damage, for example, in technological areas, warehouses where loading equipment is used.

It is recommended to place the cable with the possibility of tension. In this case, the installed section of the detector must be unwound. At the same time, the other, unused part of the detector must be wound up. This will guarantee an easy and reliable installation. The installation of a thermal cable is recommended at temperatures from -10° C and above. While operation is possible even at extreme temperatures from -40° C to +125° C.

To ensure the safety of open spaces (canopies), it is recommended to install the heating cable at a distance of 500 mm (20 inches) from the ceiling. The operation of the thermal cable can be improved by descents along the wall or racks (columns). A thermal cable installed in close proximity to the hazardous area has the added benefit of being quick to respond.

At the same time, the detector itself should not interfere with routine maintenance in the protected area. On flat ceilings, the distance between the lines of the detector(s) should not exceed 10.6 m/35 ft (UL certified). According to international standards FM distance should be 9.0m/30ft for TH68 and TH88 or 7.5m/25ft for TH105. The detector should be located at the listed distances from walls, measured at right angles within 18 inches (460 mm) of the ceiling.

Also, during installation, the so-called "dead zone" should be taken into account. In most cases, the "dead zone" is a triangle with sides 10-20 cm along the ceiling and 10-20 cm down the wall. It is not recommended to lay a thermal cable in this zone, because. this significantly reduces the fire protection of the object.

If a linear thermal fire detector is used to start systems automatic fire extinguishing, to its gasket can be presented Additional requirements in accordance with the specifics of the protected object.

MOUNTING DEVICES

For the correct and trouble-free operation of the entire system, it is necessary to use only original mounting accessories recommended by the manufacturer. The use of non-original fasteners or improvised material can damage the thermal cable, which in turn leads to false alarms and malfunction of the entire system.

Each manufacturer of thermal cable offers a wide range of fasteners. Here are a few good examples such devices:

FASTENERS FOR GENERAL PURPOSE

T-shaped fasteners allow you to quickly and easily fix the heat cable in the right place. The design of the fastener provides for a predetermined distance between the thermal cable and the surface to which it is attached, for heat removal. This fastener is convenient because there is no need to remove it when replacing or repairing the thermal cable (Fig. 1).

Figure 2 shows a fastener that uses a TwistLock lock. Fasteners can be used to fasten the thermal cable in cable trays, storage racks, concrete walls or on rooftops (fig. 2).

The cable tie is designed for fastening the thermal cable in industrial and commercial buildings. The design of this fastener rigidly fixes the thermal cable, providing heat removal and preventing its vibration (Fig. 3).

Self-adhesive clip. Suitable for use at ambient temperatures from -40° C to +85° C. There is a screw hole. With this fastener, you can easily disconnect and re-attach the heat cable (Fig. 4).

The cable clamp (fig. 5) is the most versatile type of fastener and can be used to secure the detector to a ceiling or wall, and to all corners. Resistant to UV radiation and withstands temperatures from -40° C to +85° C.

Flat tie holder (fig. 6), blind hole mounting. This fastener is mainly used for fixing the thermal cable on ceilings and in walls made of concrete or brick.

The L-shaped bracket (Fig. 7) provides a secure fastening of the thermal cable. Using the holes in the bracket design, you can adjust the position of the thermal cable in height.

L-shaped bracket (Fig. 8). The metal bracket is intended for fastening the thermal cable on oil and oil products storage tanks with a floating roof, as well as for fastening the thermal cable in places where it is necessary to fix the detector at a distance from a flat surface (wall, ceiling, etc.).

Flat tie holder (Fig. 9), secured with a screw. Its characteristics are similar to the L-shaped bracket. The heat cable is fixed with cable ties. Designed for indoor use.

FASTENING FOR STORAGE SHELVES AND CHANNELS

Figure 10 shows fasteners that are used to rigidly fix the thermal cable in various cases, including fastening the thermal cable to a channel or storage shelf.

Figure 11 shows fasteners designed for reliable fastening of the thermal cable to storage shelves (metal corners) or to the channel. This fastener has the necessary air gap between the thermal cable and the surface to which it is attached.

Beam clamp (Fig. 12). Designed for fastening the thermal cable to beam structures. Can be used in conjunction with a mounting clip.

FASTENING FOR LONG DISTANCES

For fastening the thermal cable to large areas, where it is not possible to fix it on any surface, you can use a structure consisting of a steel carrier cable (withstanding loads up to 90 kg), a bolt with a ring and a turnbuckle, providing the necessary tension of the carrier cable. It is recommended to fasten the heat cable to the cable every 3 m. The distance between the bolt with a ring and the turnbuckle, without intermediate fastening, should not exceed 75 m. In addition, it is recommended to install an intermediate fastener of the carrier cable every 15 m, in order to avoid sagging of the heat cable. The elements of this design are shown in Figure 13.

Rice. 17. An example of laying a thermal cable (marked in red) in cable trays

Rice. 18. An example of laying a thermal cable to protect the conveyor

FASTENING FOR PIPE AND CABLE TRAYS

A double tie (Fig. 14) is designed to fasten the thermal cable to pipes.

Clamp tie (Fig. 15). Universal cable tie. It is used for fastening a thermal cable to a cable, to cable trays.

ELEMENTS FOR JOINING HEAT CABLE

The crimp sleeve (Fig. 16) is designed to connect two sections of the thermal cable. For work, special crimping tools are used.

Terminal block for connecting the thermal cable. Used in conjunction with insulating tape.

Rice. nineteen. An example of laying a thermal cable to protect a tank with a floating roof

EXAMPLES OF THERMAL CABLE INSTALLATION

High efficiency, ease of installation and the ability to use with almost any fire alarm/extinguishing system make the heat cable universal remedy fire detection. Often the use of conventional fire detectors is not feasible due to their specifics: the impossibility of installation when negative temperatures and moisture, operation in the presence of dust and soot, installation in hard-to-reach places and in aggressive environments. Therefore, the use of a linear thermal fire detector is the most appropriate solution to these problems. At present, the thermal cable is widely used to protect tunnels, car parks, wood processing enterprises, oil, chemical, cement and coal preparation plants.

The peculiarity of the thermal cable is that it can be laid in close proximity to the protected equipment, as well as in all parts of the building, including elevator shafts, garbage chutes, flights of stairs and other hard-to-reach places, in addition, the thermal cable can be used to protect escalators, transformer substations, electric motors, etc.

CABLE TRAYS:

To protect cable trays, it is recommended to run a thermal cable in each tray, as well as under each tray, to protect against ignition of debris or dust. For a tray with a width of 600 mm, it is recommended to lay one thermal cable, for a tray with a width of 900 mm - two.

An example of laying a thermal cable in cable trays (Fig. 17). When protecting cable trays, the thermal cable is laid on top of all power and control cables and has a sinusoidal configuration. When installing additional cables in the tray, they must be placed under the detector. As fasteners, it is best to use double screed clamps or standard screed clamps.

rum, for this the detector must be fixed parallel to the conveyor using a carrier cable, turnbuckle and a bolt with a ring. The thermal cable itself is attached to the carrier cable using cable ties, or wrapped around the cable. The distance between the bolt with the ring and the turnbuckle, i.e. controlled area should not exceed 75 m. In addition, in order to avoid sagging of the thermal cable, it is recommended to install intermediate fasteners (anchor bolt with a ring) of the carrier cable every 15 m. It is recommended to mount the detector to the cable at least every 3 m.

FLOATING ROOF STORAGE TANKS:

To protect the floating roof tank, it is recommended to run a thermal cable around the perimeter of the floating roof (Fig. 19).

FIXED ROOF STORAGE TANKS:

We give an example of laying a thermal cable to protect a tank with a fixed roof in Figure 20 (the thermal cable is marked in red).

Rice. 20. Example of laying a thermal cable to protect a tank with a fixed roof (the thermal cable is marked in red)

ESCALATORS:

We give an example of installing a thermal cable to protect the escalator in Figure 21.

Rice. 21. An example of installing a thermal cable to protect the escalator

PARKING:

We give an example of laying a thermal cable to protect the parking lot in Figure 22. To avoid sagging of the thermal cable, when installing on flat ceilings, it is recommended to mount the detector at least every meter.

Rice. 22. An example of laying a thermal cable for parking protection

TUNNELS:

Rice. 23. An example of installing a thermal cable for tunnel protection

WAREHOUSE RACKS:

To protect warehouse racks, the thermal cable is placed parallel to the rack sections above each level of the sprinkler system with a single cable using lead wires (Fig. 24).

Rice. 24. An example of laying a thermal cable to protect storage racks

In conclusion, we note that when designing and installing linear thermal fire detectors in the Russian Federation, one should be guided by the requirements of NPB 88-2001 or SP 5.13130.2009 for linear thermal fire detectors and thermal fire detectors.

The editors would like to thank the company Fire automatics» for the provided materials

In view of the increase in production using expensive equipment and the increase in the number of technological personnel at enterprises, it is often necessary to take care of the safety of people and technological equipment. At present, due to the tightening of rules for the design of security systems, it is often necessary to think about the use of one or another kind of system.

This article will consider an innovative solution in the field of fire safety - a device presented in the form of a cable.

A linear fire detector, another name for a thermal cable, is a device capable of detecting a change in temperature in the area in which it is laid, in cases where it is impossible to install other types of fire detectors.

A linear fire detector is a pair of conductors insulated from each other with heat-sensitive insulation, sheathed in an additional protective insulating layer.

Operating principle.

The principle of operation is as follows: when a fire or overheating occurs in the area where the thermal cable is used, the insulating layer of each conductor is violated under the action of the threshold temperature, and the conductors short circuit in a separate or several sections. The control device makes a decision about changing the state on the control object.

Classification of the thermal cable according to the types of external insulation used,

which largely affects the use of the detector in specific environmental conditions:

• Thermal cable type EPC, the insulation of which is considered the most versatile insulation made of pvc material, which allows it to be used in industrial and civil construction. The sheath provides good flexibility when laying the cable at low temperatures. This ensures proper fire resistance and moisture resistance.
• The EPR type thermal cable has a polypropylene outer sheath that significantly increases fire resistance and does not spread the influence of ultraviolet radiation from the environment. Typically used in environments with aggressive chemicals, not subject to abrasion. At the same time, it functions reliably under conditions elevated temperatures environment.
• Thermal cable type XLT, the insulation of which is an insulating material made of a polymer that is highly capable of withstanding extremely low temperatures. the main purpose of this kind of isolation is the use of the detector in open areas, in conditions Far North, in refrigerators and freezers.
• The TRI type thermal cable has EPC type insulation similar in properties, but the only unique difference from other cables is the TRI cable (TRI-Wire) is capable of outputting two "Pre-alarm" and "Fire" signals, depending on the installation.
• Thermal cable type XCR in the literal sense of the word includes all the above types of sheaths. High-quality fluoropolymer casing, specially designed for special-purpose objects, with reduced smoke and gas generation, mechanically resistant to abrasion, with high resistance to low temperatures. Just like the EPR casing, it resists the aggressive effects of chemically active substances and ultraviolet exposure. And the ability to use at low temperatures allows you to make similarities with the detector type XLT. The quality of the shell makes it possible to emphasize the versatility of the insulation material used.

Classification of thermal cable according to operating conditions

consider the following figure below, which will clearly demonstrate the ability to use one or another insulation in various conditions environment.

Thermal cable classification according to temperature conditions.

In the figure, you can see the cable model and the corresponding response temperature, in the operating temperature range.

The advantage of using a linear fire detector:

The thermal cable has hypersensitivity to temperature changes along its entire length;

The presence of several temperature modes of operation, due to the manufacture of devices of various types of manufacture;

Resistance to environmental conditions;

High resistance to low ambient temperatures;

low cost and simple solutions system installation, reduced operating costs.

Principles of building the system:

The operation is based on the principle of operation with normally open contacts, therefore, the control device must have the feature of monitoring the closure of the communication loop $

It must be taken into account that when choosing this detector, it is necessary to take into account its internal resistance, due to the length of the thermal cable, 1 Ohm per 1.5 m, which subsequently may affect the length of the thermal cable line in a given section;

When choosing this system in a protected area, you should be guided by the calculation of the possible resistance of the thermal cable and evenly distribute overall length on a section into several uniform sections, otherwise a cable section longer than 2000 m may lead to false operation of the system;

Installation must be carried out in a single section, avoiding branching, division into zones, which are determined by the definition of the source of fire in one place or another;

When planning cable laying, take into account the norms and requirements for cable laying.

Next will be considered mounting devices that are used in systems security and fire alarm using a linear fire detector, based on equipment supplied by Protectowire, approved by VNIIPO EMERCOM of Russia.

Mounting components.

Mounting zone box ZB-4-QC-MP tight connection of the linear detector and the communication loop. The design of the box allows for reliable protection connecting node from external environmental influences, helps to ensure high-quality connections in a wide range of operating temperatures.

An example of application, discussed in the figure below, shows that the contact connectors enclosed inside the box with such use make it possible to adequately ensure the connection of the thermal cable and the communication cable, as well as additional resistance, ensuring its integrity.

Compression sleeve SR-502

its main purpose is to ensure the sealing of the cable entry into the mounting zone box ZB-4-QC-MP. A type-setting coupling made of steel elements and sealing rings allows you to get a reliable tight connection with the cable and the box, while not damaging the heat-sensitive sheath of the cable cores.

Fastening devices.

Designed for fast, reliable and at the same time safe installation, mounting elements allow you to gradually fix the cable during the pulling process, while ensuring the integrity of the thermal cable.

The fasteners presented below allow installation without additional stretching and squeezing of the cable insulation.

waw clamp

the appearance of the device allows you to guarantee a simple and reliable fastening cable detector to the surfaces on which it will be laid. The principle of use lies in the fact that a cable is placed inside the clamp, the material of which, depending on the laying conditions, can be used in two types, and without pressure on the outer sheath, it is clamped.

According to the type of material used, the clamp can be of two types: nylon (WAW-N) and polypropylene (WAW-P). Polypropylene clamps are applicable when used in high temperature environments, and nylon clamps in low temperature environments up to -40°C, and +88°C, respectively, for polypropylene.

There are no features of installation on straight sections, but in the corners there is a shift in the installation point of the fastener inside the cable bend by 1.3-2 cm from the intersection of the cable lines, after fixing on straight sections.

Also, for straight sections, more primitive type OHS mounts are applicable.

Line clamps OHS

are used to fasten a linear fire detector in straight runs, as recommended by the manufacturer, between clamps of the WAW type, while providing the main support of the detector.

The clamp type OHS-1 is made of galvanized steel, which justifies its use for indoor use, and the clamp type OHS-1/4-SS is made of steel, which justifies its use for outdoor installations.

The clamp is fixed by essentially any fastener (bolt, screw, stud, etc.).

The considered mounting fasteners allow mounting the thermal cable on a plane, but as a rule, when installation work it is not always possible to carry out work only on a plane, or it is not possible to install a clamp on it, in some places it is necessary to hang the detector to a building structure, where it will not be possible to mount for one reason or another, the methods considered earlier, resort to the use of clamps, which, without additional violation the integrity of the building will allow the laying of the cable.

BC series clamp kit

are used for laying the detector to building structures, without violating its integrity, and reasonable use of labor costs and installation time. They are used in the installation of thermal cables on cables organized in trays, on metal structures, fachferk structural elements, etc.

The principle of fastening is that the BC type clamp is fixed to the structure, and the thermal cable is already fastened to it through the WAW type clamp.

There are two types of clamps depending on where the clamp is used.

Clamp BC-2, material steel, used for laying thermal cables indoors.

Clamp BC-3, galvanized steel, used for mounting the thermal cable on outdoor structures.

Adhesive type mounting kit

in cases where it is not permissible to make mechanical fastening, and the temperature and environmental conditions allow, without any special requirements for the material, a fastener consisting of a mounting platform and a cable tie is used, which is glued to a specialized, industrial adhesive, which ensures speed of installation and ease of work.

To ensure the displacement of the thermal cable relative to the attachment point, a RMC L-Mount Bracket. L-shaped holder, at the end of which the WAW clip or push-button has five holes for adjusting the offset distance. As well as all previously considered fasteners, this holder is made either from sheet steel or stainless steel, which makes it possible to use it both indoors and outdoors.

Mounting clips CC-2.

They are a composite system of fasteners, which allows you to quickly and conveniently mount a linear fire detector along a cable tray with direct attachment to the tray. A typical "Caddy" clip has a specific bend on one of the edges, which allows you to catch on the edge of the cable tray and hold it securely when hanging on the other of its edges of the thermal cable, fixed by means of a latch fastener or a WAW type clamp.

For these purposes, the manufacturer produces two modifications of clamps for a tray with a thickness of 1.6-4.0 mm and a tray with a thickness of 4.0-6.0 mm, models CC-2N and CC-2W, respectively.

When using a different "Caddy" clamp, it is possible to fasten to thicker elements of the cable tray in the same way.

Mounting clips CC-10.

Similar in principle to CC-2 clamps. In addition to everything previously said given type the clamp has the possibility of additional mechanical action for fastening the clamp to the tray, when using a bolted connection, in this case the clamp is recommended for mounting a linear fire detector in places subject to vibration.

Fastener modifications are represented by two types:

CC-10N are used for trays with a wall thickness of 3.2 - 6.4 mm;

CC-10W are used for trays with a wall thickness of 7.9 - 12.7 mm.

Less complex but also functional way fixing the thermal cable may be possible in the presence of such products.

Mounting clip HPC-2.

Resistant to UV radiation of the environment and having a bracket that allows you to hook the fastening lock to a material with a thickness of 1.5 - 6.4 mm, this clamp will allow you to install a linear fire detector without additional labor. The thermal cable is inserted into the clamp, which is attached to the structure corresponding to the purpose. Material - nylon.

Same simple method fasteners, it is possible to install a thermal cable using clamps.

Clamps PM-3.

When laying a linear fire detector along sprinkler fire extinguishing systems, it was necessary to solve the problem of hanging a thermal cable to a pipe line, for which such clamps were introduced.

The clamp-in-clamp system allows one clamp to fasten the fastener, and the second one attracts a thermal cable, while there is no contact between the detector and the pipe, and most importantly, the place of cable compression is not pulled, while the inner insulating layer of the cores is not disturbed.

Nylon clamps are operated at temperatures from -40 °C to +85 °C, while the installation temperature must not be below 0 °C.

All of the above in one way or another refers to one method of installation. Next, we will consider the method of laying on a string using a carrier cable.

Hcurrent tros.

An exclusive way to supply a linear fire detector is that the carrier cable is already integrated into the detector. Stainless steel threads are located directly under one outer braid. The cable wraps around the threads with a period of 0.3 m.

The installation method is extremely clear, is that the ends on straight section the fire detector is attached to fixed parts or lugs and is stretched with a lanyard.

The length of such a section should not exceed 76 m, otherwise the cable may break.

Also, to prevent breakage of the thermal cable, supporting elements are installed throughout the area of ​​\u200b\u200buse of the linear fire detector. The frequency of use of such elements is determined by the operating conditions, which shows practice for outdoor use, it is recommended to use the element more often in order to provide support and load distribution, from ice, snow load for the entire length of the thermal cable.