Electronic pressure regulation. Pump station adjustment: pressure switch

What could be better in private system water supply? Of course, it will take a lot of time, care and effort to organize it. For proper arrangement, first of all, a pumping substation is needed, and in order for it to work for a sufficiently long period of time, it is advisable to install a water pressure switch. It is able to prevent overheating and, consequently, damage to the installation.

If a water pressure sensor is installed in your water supply system, you can guarantee enough water supply without emergency operation. long term. The principle of operation of the protective block is organized on the minimum and maximum water pressure in the source. If the water pressure rises, one of the springs is compressed, and when the water pressure is lowered, the spring expands. Due to these manipulations performed by the springs, the contacts of the pressure switch for water are opened, due to which the pumping station is turned off and on.

Using the example of the capacity of the water pressure switch, it looks like this: the pump starts pumping water into the storage tank (which is installed in most cases), when it is filled to the maximum, the pressure rises and the relay is activated. When the consumer turns on the water tap, the pressure in the hydraulic tank gradually decreases and, at the minimum value of the relay, starts the pump again. This process is repeated in a circle. Watch the video material for our article.

How to adjust the pressure sensor for the pump?

The most important process in the arrangement private well is the pressure switch adjustment pumping station. It is important to use the right principle here. This question can take a lot of time, so you need to follow a clear algorithm.

Important! In addition to a single check, you will regularly measure the pressure in the hydraulic tank with an approximate frequency of 1 time in 30 days.

1. When the normal operating mode is selected, it should be adjusted using the regulator. If some indicator of pressure does not suit you, you can bleed or pump it up. The recommended indicator is at least 1 atmosphere in the accumulator.
2. If you yourself assembled the pump in the water supply system, the adjustment of the pressure switch should be carried out in without fail. To begin with, the small nut and the maximum pressure indicator are adjusted. Make sure that this value is not higher than the factory norm, since in such situations it is necessary to manually turn off the pump.
3. Next, the pressure switch of the pumping station is set to the minimum value with a large nut in the pressure switch for the pump. This can be achieved by draining water from the accumulator. In this case, a pressure gauge must be installed in it. At the moment when the arrow on the scale shows the minimum value, the pump should turn on. Automation is regulated according to the meter readings.

Important! Remember that the lower pressure is best adjusted so that it is 10% higher than the air pressure in the tank. Otherwise, it is fraught with the speedy wear of the rubber membrane.

1. In some cases, it is permissible to set pressure limits according to one's own preference. It should be remembered that so the reference point should be a large nut, that is, the lower pressure aisle. The upper limit can only be the one for which the entire pumping system. It is also possible to use a pressure switch rm 5.

We draw the attention of the consumer that the regulator must be selected depending on the conditions of your water supply and according to technical characteristics. well pump. In work, the connection diagram of the pressure switch must be used.

Automatic equipment for home pumps

Automation involved in the equipment modern pumps most often, it consists of several devices. What are these devices, consider below:

In order for the operating parameters autonomous systems water supply (in particular, the pressure in the pipeline) could be automatically regulated using various technical devices, one of which is a water pressure sensor. This element of water supply systems, in which water is supplied from wells through pumping stations, allows not only to control the parameters of such systems, but also to control their operation. The water pressure sensor in the water supply system allows you to automatically turn on and off pumping stations without human intervention.

Algorithm of work and purpose

The water pressure control sensor (switch, pressure sensor) operates according to the following algorithm:

• At the moment when the taps open and the volume of fluid in the accumulator decreases, the water pressure in the water supply decreases.
• When the pressure in the water supply system reaches the minimum allowable value, the contacts of the sensor that regulates this parameter close.
• Closing the contacts of the pressure sensor leads to the start of the pump, which is responsible for supplying water from the well.
• When pumping water from a well, the pressure in the water supply begins to increase.
• After the water pressure in the water supply reaches the maximum allowable value, the sensor contacts open, which leads to the shutdown of the pumping equipment.

Working in a similar mode, water pressure sensors allow you to keep the pressure of the liquid in the water supply at a constant level. If you do not use such a device in the pipeline, then the pump supplying water will have to be turned on and off manually. This will not only prevent the water pressure in the system from being maintained at a constant level, but can also lead to water hammer and pumping equipment in idle mode.

Water pressure sensors installed on one of the nodes of the water supply system perform another important function - they signal the current pressure and display data on its value on the control devices, the simplest of which is the manometer.

Thus, by installing a water pressure sensor (electronic or mechanical), they ensure the stability of the water supply system, and also protect the elements of its equipment from negative factors such as water hammer and dry running of the pump.

Design features

As mentioned above, there are both mechanical and electronic water pressure switches. For both, the main working organ is the membrane, which acts as one of the walls of their internal container, into which water enters. Deviating under the pressure of water, the membrane acts on the remaining elements of the sensor, as a result, the device is triggered.

The elements affected by the deflecting membrane in mechanical sensors are contacts that, when closed or opened, turn on and off the pumping equipment. The electronic pressure sensor works on a slightly different principle. The deformation of the membrane in such a device is converted into a control electrical analog signal, which is then amplified, digitized and fed into the pipeline automatic control unit.

Mechanical pressure sensors, which are also called contact, are used more often than electronic ones. This is explained both by the simplicity of the design of such a device and its more affordable cost. In particular, mechanical water pressure sensors are regularly installed in domestic heating and water supply systems.

The design of the mechanical sensor is:

• branch pipe, with the help of which the device is connected to the elements of the pipeline;
• membrane;
• contact Group;
• two springs of different diameters, through which the maximum and minimum pressure levels are set at which the device should operate.

A larger diameter spring, installed in mechanical type sensors, determines the level of water pressure in the pipeline at which the device will operate and turn off the supply pump. The second spring is responsible for the lower limit of the sensor's response, or to be more precise, the range of values ​​beyond which the sensor will turn on and start the pump that supplies water to the pipeline.

The design of mechanical sensors provides for the ability to adjust the degree of compression of both springs. When a spring of a larger diameter is compressed, the value of the water pressure at which the device will operate increases. If you compress a spring of smaller diameter more, then the pressure difference between the response levels will increase.

If you decide to install a pressure sensor yourself, first read the information on how to do it correctly. Usually, the part of the water supply that is located after the pump and accumulator, in front of the filter elements, is chosen as the place for installing a sensor or pressure switch. This is explained by the fact that this part of the water supply system is characterized by smaller pressure surges. It should also be borne in mind that the operation of many models of water pressure control sensors is only allowed indoors. This must be indicated in the instructions for such devices.

To install the sensors, special tees-splitters are used, which allow using one mounting element to connect the sensor itself, the accumulator and the pressure gauge to the water supply system. When installing the sensor, in addition to the tee, an additional adapter may be required, the purchase of which should be taken care of in advance. In any case, the scheme for connecting the relay to the water supply is determined by the design and technical specifications the last one.

Separate models of sensors placed in a waterproof housing can be installed directly on the water pump using a special fitting. Sensors of this type thanks to this design, they are successfully operated together with pumping equipment inside a caisson or even a well.

After the mechanical part of the process of installing a water pressure switch or sensor is completed, it is necessary to connect the appropriate contact groups to the pump and ground the device. When choosing electrical cables for connecting such sensors, one should first of all take into account the power of the pump operating in the system. So, when using pumping equipment with a power of 2 kW, cables with a cross section of at least 2 mm 2 should be used.

After you have installed the water pressure switch with your own hands and made all the necessary connections, you can turn on the pump and check the operation of the entire system. The fact that it is functioning normally will be indicated by an increase in pressure in it, which can be determined from the readings of the pressure gauge.

Self-configuration

Despite the fact that in most cases the operating parameters of the differential pressure switch are already set by the manufacturers, there may be situations when the adjustment procedure needs to be done by hand. The optimal difference between the values ​​\u200b\u200bof the water pressure in the pipeline, at which the pump should turn on and off, should be 1 atm. In this case, the lower limit at which the sensor is triggered is set so that it is 0.2–0.5 bar less than the pressure that the pump used can withstand.

Before you start adjusting the operating parameters of the sensor or relay with your own hands, you need to check the pressure level in the accumulator. To do this, you must perform the following steps:

• Disconnect all elements of the system from the network and drain the water.
• Remove the side cover of the accumulator and check the pressure level in it, for which you can use Automobile compressor equipped with a manometer.
• If the pressure level is less than 1.5 atm, it is necessary to increase it by turning on the supply pump.
• When too high level pressure must be reduced by pressing the nipple.

After such a check, you can proceed to adjust the sensor, which is performed in the following sequence:

1. All elements of the system are disconnected from electrical supply and water is poured out of it.
2. After draining the water, make sure that the pressure gauge shows zero.
3. Then turn on the pump and begin to fill the system with water.
4. When turning off the pumping equipment, the value at which this happened is fixed on the pressure gauge.
5. After that, they begin to drain the water and, when the pump is turned on, the pressure level is also fixed.
6. Disconnect the system elements from the power supply and remove the sensor cover.
7. Loosen the nut, with which the compression ratio of the small diameter spring is adjusted.
8. Using a nut to compress a large diameter spring, set the minimum pressure level at which the sensor will operate. In this case, it should be borne in mind that the compression of this spring increases this parameter, and its weakening decreases it.
9. Again fill the system with water, then begin to drain it and fix the pressure level at which the pump will turn on.
10. If this value does not meet the required parameters, it is necessary to adjust the compression ratio of the large diameter spring again.
11. By changing the degree of compression of a spring of small diameter, the maximum water pressure threshold is set at which the pump will turn off. When such a spring is compressed, the difference between the pump actuation thresholds increases, and when it is weakened, it decreases.
12. Turn on the pump that fills the system with water, and fix the pressure level at which it turns off.
13. If the pressure level at which the pump turns off does not correspond to the required parameters, re-adjust the compression ratio of the small diameter spring. This procedure should be carried out until the required pressure difference at which the pump turns on and off is reached.

For a stable supply of water with the required pressure values, it is not enough just to buy a pumping station. The equipment still needs to be set up, launched and properly operated. Admit it, not all of us are familiar with the intricacies of customization. And the prospect of spoiling devices with incorrect actions is not very attractive, do you agree?

You will learn about the causes of pressure drops and learn how to eliminate them. Graphic and photo applications will explain how to properly configure pumping equipment.

A ready-made pumping station equipped with the manufacturer is a mechanism for forced water supply. The way it works is extremely simple.

The pump pumps water into an elastic container located inside a hydraulic accumulator, also called a hydraulic tank. When filled with water, it expands and presses on that part of the tank that is filled with air or gas. The pressure, reaching a certain level, causes the pump to turn off.

During the intake of water, the pressure in the system drops, and at a certain moment, when the values ​​\u200b\u200bset by the owner are reached, the pump starts working again. The relay is responsible for turning the device off and on, the pressure level is controlled using a pressure gauge.

Violations in the operation of a household pumping station can cause breakdowns of plumbing equipment

The article we recommend will acquaint you with the principle of operation, varieties and proven installation schemes in more detail.

Causes of hardware problems

The statistics of malfunctions in the operation of domestic pumping stations says that most often problems arise due to a violation of the integrity of the membrane, pipeline, water or air leakage, and also due to various contaminants in the system.

The need to intervene in its work may arise due to many reasons:

• Sand and various substances dissolved in water can cause corrosion, lead to malfunctions and reduce equipment performance. To prevent clogging of the device, it is necessary to use filters that purify the water.
• The decrease in air pressure in the station causes frequent operation of the pump and its premature wear. It is recommended to measure the air pressure from time to time and adjust it if necessary.
• The lack of tightness of the joints of the suction pipeline is the reason that the engine runs without turning off, but cannot pump liquid.
• Improper adjustment of the pressure of the pumping station can also cause inconvenience and even breakdowns in the system.

To extend the life of the station, it is recommended to periodically audit. Any adjustment work must begin with disconnecting from the mains and draining the water.

Energy consumption and maximum head should be checked periodically. An increase in energy consumption indicates friction in the pump. If the pressure drops without leaks detected in the system, then the equipment is worn out

Correction of errors in work

Before embarking on a more serious intervention in the operation of the equipment, it is necessary to take the simplest measures - clean the filters, eliminate leaks. If they do not give results, then proceed to next steps trying to find the root cause.

The next thing to do is to adjust the pressure in the accumulator tank and.

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The following are the most common malfunctions in the domestic pumping station, which the user can try to solve on his own. For more serious problems, contact the service center.

Violation of the rules of operation

If the station is continuously running without shutting down, probable cause is the incorrect adjustment of the relay - set high pressure shutdown. It also happens that the engine is running, but the station does not pump water.

The reason may lie in the following:

• When first started, the pump was not filled with water. It is necessary to correct the situation by pouring water through a special funnel.
• The integrity of the pipeline is broken or an air lock has formed in the pipe or in the suction valve. To find a specific cause, it is necessary to make sure that: the foot valve and all connections are tight, there are no bends, narrowings, hydraulic locks along the entire length of the suction pipe. All malfunctions are eliminated, if necessary, replace damaged areas.
• The equipment works without access to water (dry). It is necessary to check why it is not there or to identify and eliminate other causes.
• The pipeline is clogged - it is necessary to clean the system of contaminants.

It happens that the station very often works and turns off. Most likely this is due to a damaged membrane (then it is necessary to replace it), or the system is missing. In the latter case, it is necessary to measure the presence of air, check the tank for cracks and damage.

Before each start, it is necessary to pour water into the pumping station through a special funnel. She must not work without water. If there is a possibility of the pump running without water, you should purchase automatic pumps equipped with a flow controller

Less likely, but it can happen that it is open and blocked due to debris or a foreign object. In such a situation, it will be necessary to disassemble the pipeline in the area of ​​\u200b\u200bpossible blockage and eliminate the problem.

Engine malfunctions

Engine household station does not work and does not make noise, possibly for the following reasons:

• The equipment is disconnected from the power supply or there is no mains voltage. You need to check the wiring diagram.
• The fuse has blown. In this case, you need to replace the element.
• If you cannot turn the fan impeller, then it is jammed. You need to find out why.
• Relay damaged. You need to try to adjust it or, if it fails, replace it with a new one.

Engine malfunctions most often force the user to use the services of a service center.

Problems with water pressure in the system

Insufficient water pressure in the system can be explained by several reasons:

• The pressure of water or air in the system is set to an unacceptably low value. Then you need to configure the relay operation in accordance with the recommended parameters.
• pipeline or Working wheel pump is blocked. Cleaning the elements of the pumping station from contamination may help solve the problem.
• Air enters the pipeline. Checking the elements of the pipeline and their connections for tightness will be able to confirm or refute this version.

Poor water supply can also be caused by air being drawn in due to loose plumbing connections, or the water level has dropped so much that air is being pumped into the system when it is drawn in.

Poor water pressure can create significant discomfort when using the plumbing system

Revision of the storage tank

Starting work on adjusting the equipment, disconnect the system from the network, close the pressure valve on the side of the water intake. The tap is unscrewed and the water is drained, and the remnants are drained through the pressure hose, disconnecting it from. First, check the air pressure in the accumulator tank.

The role of the accumulator in the operation of the system

The membrane tank of the pumping station is, in fact, a metal container with a rubber pear located inside, which is designed to collect water.

AT free space air is pumped between the rubber bulb and the walls of the tank. In some models of hydraulic accumulators, the tank is divided in half by a membrane that delimits the tank into two compartments - for water and air.

The accumulator tank maintains pressure in the system and creates a small supply of water. Once a month, the pressure in the hydropneumatic tank should be checked with the pump turned off and the water drained from the supply pipe.

The more water enters the device, the more it compresses the air, increasing its pressure, which tends to push the water out of the tank. This allows you to maintain a stable water pressure even when the pump is idle.

The accumulator requires regular maintenance, removal of air from the pear, which enters it along with water in the form of small bubbles and gradually accumulates there, reducing the usable volume.

To do this, on top of large tanks is provided special valve. With small containers, you have to contrive to remove air: de-energize the system and drain and fill the tank several times.

The selection of a hydraulic tank by volume is made taking into account the greatest value water consumption for a particular consumer. The allowable number of starts per hour specified by the manufacturer is taken into account, as well as the nominal values ​​​​of the cut-in pressure, cut-out pressure and user-specified pressure in the hydraulic tank

Air pressure control

Although the manufacturer adjusts all elements of the pumping station at the production stage, it is necessary to double-check the pressure even in new equipment, since at the time of sale it may decrease slightly. The device that is in operation is inspected up to two times a year.

For measurements, the most accurate pressure gauge is used, because even a small error of 0.5 bar can affect the operation of the equipment. If it is possible to use a car pressure gauge, with a scale, with the smallest graduation, this will provide more reliable results.

Air pressure indicator in membrane tank must correspond to 0.9 times the switching pressure of the pumping station (set using a relay). For tanks with different volumes, the indicator can be from one to two bar. Adjustment is carried out through the nipple, pumping or bleeding excess air.

For normal operation, the station is equipped with mandatory control and regulation devices:

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The less air is pumped into the system, the more water it is able to accumulate. The water pressure will be strong when the tank is full, and more and more weakened when water is taken.

If such drops are comfortable for the consumer, then the pressure can be left at the lowest acceptable level, but not less than 1 bar. A lower value can cause the bulb filled with water to rub against the tank walls and damage it.

To install in a strong water pressure, it is necessary to fix the air pressure in the range of about 1.5 bar. Thus, the difference in pressure between a full and empty tank will be less noticeable, providing an even and strong flow of water.

Using a pressure switch

Responsible for the automation of the system is a device that controls the pumping station, performing the function of turning the device on and off. It also prevents the system from building up excessive pressure.

The pressure switch controls the on/off cycles when a user-defined operating pressure is reached. The performance of the pressure switch is controlled by a pressure gauge

#1: Working principle of the pressure sensor

The main element of the relay is a group of contacts, which is fixed on a metal base and is responsible for turning the device on and off.

Nearby are two springs different sizes to regulate the pressure inside the system. From below, a membrane cover is attached to the metal base, under which the membrane itself and a metal piston are located. From above everything is closed with a plastic cap.

There are several stages in the operation of the operating device:

1. When you turn on the tap, water for some time flows to the plumbing point from the filled tank. In this case, the pressure present in the system gradually begins to fall, and the membrane stops pressing on the piston. The contacts close, the pump turns on.
2. The pump works by pumping water to the consumer, and when all the taps are turned off, it fills the tank with water.
3. With the gradual filling of the accumulator tank, the pressure increases, and it begins to act on the membrane, and it presses on the piston. As a result, the contacts open and the pump stops.

The frequency of switching on the station, the pressure of the water, and even the service life of the equipment depend on how the relay is configured. If the parameters are set incorrectly, the pump will not work at all or will work continuously.

The pressure switch piston and a sensitive metal plate that reacts to the pressure created by the hydraulic tank membrane are hidden under the housing - access to them is completely closed

#2: Adjusting and calculating the required pressure

The new device already has factory relay settings, but, nevertheless, it is better to check them additionally. When starting to set up, it is necessary to find out the values ​​recommended by the manufacturer for setting the allowable pressure threshold (for closing and opening contacts).

In the event that due to incorrect adjustment, the manufacturer has every right to refuse its warranty obligations.

The calculation of the allowable pressure, when turning the device on and off, is carried out by the manufacturer, taking into account the expected features of operation. They are taken into account in the development of operating parameters for different models of pumping stations.

The inclusion value is equal to the sum of:

• The required pressure at the highest point of the water supply system, where water is taken;
• Differences between the height of the highest point of water extraction and the pump;
• Losses in the water pressure pipeline.

The turn-off rate is calculated as follows: plus one bar to the turn-off pressure and subtract one and a half bar. In this case, the shutdown pressure must not be allowed to exceed the maximum allowable pressure that occurs at the outlet of the pipeline from the pump.

A common mistake that affects the operation of a pumping station is not taking into account the entire amount of horizontal and vertical sections, as well as hydraulic losses during the transportation of water to draw-off points.

Before changing the settings, it is necessary to fix the previous readings using a pressure gauge. Turning on the pump, record the pressure at the time of turning it off and on. This will help determine in which direction to carry out the adjustment - in the direction of decreasing or increasing.

It must be remembered that any change threshold pressure in the relay also requires corresponding changes in the air compartment of the accumulator

The next steps are in the following order:

1. Disconnect the station from power, drain the water and open the relay cover with a wrench.
2. The switching pressure of the pump is adjusted by turning the nut that holds the large spring (P). By twisting it in a clockwise direction, the spring is compressed and the required switching pressure is set. In various models of the device, the allowable indicators can range from 1.1 to 2.2 bar.
3. By turning the small nut (∆P) clockwise, you can increase the gap between the switch-off and switch-on pressure of the device, which is usually 1 bar. Thus, the shutdown pressure can be fixed at values ​​in the range from 2.2 bar to 3.3 bar.

An important nuance is that the small spring does not adjust the shutdown threshold, as some mistakenly understand.

It sets exactly the delta between the values ​​​​of switching on the station, and its shutdown. That is, a fully relaxed spring will not create a difference - the delta will be zero and the on and off values ​​will be the same. But the more you tighten it, the greater the difference between them will be.

The small pressure switch spring is more sensitive and must be compressed very carefully

Check the correctness of the set indicators using a manometer. If it was not possible to achieve the required values ​​on the first attempt, the adjustment is continued.

#4: Select non-standard pressure values

You can set a different level of pressure in the device, different from the recommendations of the manufacturer, adjusting the equipment to the individual needs of the user. By increasing the range when turning on / off, they achieve more rare station operations.

This makes the service life of the device longer, but gives the water pressure an uneven character. By reducing the difference, they achieve a stable pressure, but this way the pump will work more often.

Conclusions and useful video on the topic

How to adjust the pressure of the station, the video will demonstrate:

Video on what to do if the station often works:

When self-adjusting the pumping station, it must be borne in mind that sometimes changes in factory recommendations can worsen the operation of the plumbing system. The pump, hoses, plumbing fixtures - all have pressure limits, the violation of which will lead to breakdowns. Therefore, before embarking on independent actions, it is better to ask for advice from an experienced specialist.

Please leave comments in the block below. Share personal experience in the installation and operation of pumping stations, as well as in their configuration. Ask questions, report shortcomings in the text, post photos on the topic of the article.

The pump pressure switch is a device that allows you to control the operation of pumping equipment in automatic mode.

How a pressure switch works

The pump pressure switch is spring block, which ensures the transmission of a signal received from a membrane that receives water pressure to electrical contacts that close and open an electrical circuit.

During operation of the pump, the accumulator is filled, the pressure in it increases, which leads to stretching of the pump relay membrane. The membrane presses on the spring block, the springs are compressed, which leads to the opening of the contacts electrical circuit. The pump is disconnected from the network and stops.

As water is consumed, the pressure in the accumulator decreases, which leads to a decrease in membrane deformation and a decrease in its pressure on the spring block. The springs weaken and close the contacts of the electrical circuit. As a result, the pump turns on, and the process is completely repeated.

The standard pressure switch setting is between 1.4 and 2.8 bar. At the lower limit (1.4) the pump is switched on, at the upper limit (2.8) it is switched off. Such a wide pressure range results in frequent pump activation. You can increase the rest period of the equipment by adjusting the pump relay. But you will have to start work with a hydraulic accumulator.

Adjusting the pressure in the accumulator

The operation of the pump relay directly depends on the pressure in the accumulator installed in the system. Therefore, before changing the settings in the relay, the battery is disconnected from the water supply network, having previously de-energized it. Then water is completely drained from it and only then the pressure is measured. For measurement, you can use a car pressure gauge, with which you can check tire pressure.

The pressure rate is 1.5 atm. If this indicator is lower for the accumulator, the pressure level is increased by pumping up the accumulator with the same car pump.

The accumulator is ready, you can change the relay settings.

Relay setting

To do this, the pumping station is reassembled and put into operation. Pressure adjustment is carried out on the working equipment. To do this, use two adjusting screws located under the cover of the automation group of the device. The cut-in and cut-out pressure levels are adjusted separately.

The sequence of actions is as follows.

1. The inclusion of the pump in operation is fixed. At the same time, the pressure in the water supply system is measured.
2. The station is disconnected from the power supply
3. Removing the relay cover
4. Adjustable (loosened or vice versa tightened) screw with the appropriate marking
5. The pressure in the water supply network decreases (you need to open the tap and drain some of the water)
6. The pumping station is put into operation. This measures the new pressure at which the pump will start working.
7. If the switching pressure does not correspond to the desired one, the process is repeated again.

As you can see, you can adjust the pump relay yourself, without the help of specialists.

Automatic operation of the pumping station is not possible without the use of a water pressure switch for the pump. This device rigidly sets the limits for the permissible value of pressure in the system and the pressure used by the consumer. As a result, there is always a stabilized water pressure at the outlet, and the pump only works when there is a need for water.

Principle of operation

Pressure switches can be mechanical and electronic. It is mechanical devices that have become widespread due to their simplicity, reliability and reliability. Their configuration requires a minimum of effort and can be performed at the point of connection.

The main task of the pressure switch is to control the pump. The supply line of the pump is switched through it. Switching on and off is carried out depending on the pressure in the pipes. For an automatic pumping station, consisting of a pump and an accumulation tank, the workflow is as follows:

• The nominal pressure of the system is set, as well as the allowable limits for the minimum and maximum pressure.
• When the minimum threshold is exceeded, the pump turns on and pumps water to the consumer and into the storage tank.
• When the upper set threshold is exceeded, the pump turns off.

The pressure switch just determines the permissible limits of the minimum and maximum pressure and turns on the pump according to the above algorithm.

According to the method of controlling the pump, a power and signal relay are distinguished. The first directly controls the power supply of the pump, and when choosing, you should focus on the maximum allowable current. The second, signal, switches or generates a low-voltage signal for the control unit.

The device is structurally divided into three parts:

• hydraulic block, membrane;
• detection unit, spring actuation adjustment unit;
• power or signal relay.

The hydraulic block of a simple mechanical pressure switch is a sealed chamber, inside of which a membrane is located. On one side of the chamber there is a fitting for connecting to water pipe. Water enters one part of the chamber and presses on the membrane; on the other hand, a movable rod is connected to it, which exits from the other side of the chamber.

The detection unit determines the triggering conditions of the relay and responds to pressure changes in the system. A lever plate is connected to the rod coming out of the sensor chamber to control the power relay. Depending on the pressure applied to the membrane, the relay closes or opens the contacts. To balance the membrane and determine the maximum allowable actuation level, a spring block is attached to the stem, exerting pressure on it comparable to the effect of water pressure. The tension of the springs is adjusted using nuts and pressure washers.

A power or signal relay is a group of plug-in contacts and terminal blocks for connecting a power line to a pump or a signal line for a control unit.

The key element of the device is the spring control unit. If you open any mechanical relay, you will find one large spring and one small one in it. It is they who determine the levels of operation.

A large spring exerts the main pressure on the sensor rod, determining the maximum allowable division, at an increase in which the relay contacts open and the pump turns off.

The smaller spring determines the pressure differential, the difference between the upper and lower thresholds.

Both springs have adjusting nuts that control the degree of tension. It is important to correctly understand the purpose of the springs.

If you change the degree of compression of a large spring, then both relay thresholds will simultaneously shift to one side or the other.

If you act on a smaller spring, and do not touch the larger one, only the lower threshold changes.

Wiring diagram

The pressure switch is activated after the pump and immediately before entering the storage tank. To protect the sensor from contamination, the effects of pressure surges as a result of starting and stopping the pump, the following should already be installed in front of it:

• coarse filter;
• pump;
• shut-off valve;
• check valve;
• fine filter;
• drain to the sewer through the breakdown valve.

For the normal functioning of the automatic pumping station, the storage tank is set to maximum pressure higher than the required nominal for water supply by about 0.5-1 bar. The upper threshold of the relay is set to 0.2-0.3 bar below the maximum. The differential sets the bandwidth of the allowable pressure and can be up to 2 bar.

The smaller the differential, the difference between the upper and lower thresholds, the more often the pump turns on, but the more stable the pressure on the consumer side.

The higher the differential, the less often the pump turns on, but significant changes in pressure are possible on the consumer side.

The supply wires from the switchboard and the pump power wires are connected to the relay terminals in accordance with the manufacturer's instructions, focusing on the signatures and color marking of the wire. If there is a terminal marked "ground", the cable from the common ground must be connected without fail.

Adjustment

The relay does not even require additional configuration before use with most pumping stations. If you choose a relay with a suitable maximum allowable trip threshold, then the settings from the factory already have optimal values. For pumping stations designed to supply water in a private house, this is most often turned off at 2.5 (3) bar and turned on at 1.5 (1.8) bar.

However, to specify specific settings when the factory settings do not suit you, you must perform the initial setup of the equipment. To do this, it is mandatory to install a pressure gauge connected to the same five-pin fitting as the relay. It is assumed that the entire system has already been assembled and is ready for the first launch, if necessary, water has already been drawn up to check valve, excluding idling of the pump, and in storage tank there is already a minimum amount of water.

Before setting, select:

• maximum allowable pressure in the system;
• minimum pressure;
• pressure of the air chamber of the hydraulic accumulator with drained water.

Before adjustment, it is necessary to remove the cover from the sensor and prepare appropriate socket wrenches for the adjusting nuts.

The procedure is as follows:

1. Turn on the pump to fill the tank.
2. When the pressure gauge reading reaches the required maximum value, for example 3 atm, turn off the pump manually. If the relay worked ahead of time, then turn the nut of the main spring clockwise one or two turns and repeat this step.
3. At the steady pressure in the system at the maximum level, turn the nut of the main spring counterclockwise until the relay trips. This will set the upper threshold.
4. Open any faucet in the house and wait until the pressure gauge reaches the required lower threshold. It is set 10% more than the pressure of the accumulator air chamber.
5. If the relay has already worked while draining the water, then turn the nut of the smaller spring counterclockwise, if the relay did not work, then turn it clockwise until the relay clicks.
6. Turn on the pump and check the correct setting of the upper threshold, if it is too high or too low, finally adjust by tightening or loosening the nut half a turn according to paragraph 3.
7. Drain the water through the tap until the lower threshold works, and the pump turns on again. Check the required value and, if there are deviations, repeat the setting according to point 5.

Electronic relay

Along with the mechanical pressure switch, electronic switches are also used. More often they represent a full-fledged pump control unit, including a device soft start and protective operation and, accordingly, the installation of the upper and lower thresholds in the operating mode.

For adjustment, adjusting bolts located on the body of the device are used. For convenience, markings and marks are often applied around the bolts for orientation at given pressures.

Electronic relays do not provide special advantages, however, they are smaller and do not emit extraneous sounds when triggered, although this is not relevant when installed directly next to the pump.