Water pressure sensor in the water supply system

Every owner of a private home always wants his home to be comfortable and cozy. The main amenities are of course sewerage and water supply. The optimal solution to the issue of water supply to a private house is the installation of a submersible or deep pump or pump station. The installation is called an automatic pump because it supplies water to the house and itself maintains the necessary pressure in the water supply system during its operation.

Such automatic water supply stations are used both in private houses and in cottages, as well as in apartments. Their advantage lies in the leveling of hydraulic attacks in the water supply system, and in the event of a drop or a power outage, they themselves store the required water reserve, that is, the reserve.

Wherever a pump or pump station is used, they always have adjustment sensors. With their help, the pumps are switched on and off. Therefore, when acquiring such equipment, it is extremely important to select the right range when the pump is set correctly. If this range is too large, the pump will react too much to the fluctuations, and then the water pressure sensor in the pipeline will operate very often. If the adjustment is too small, the pump will be turned on more frequently, and as a result, it will lead to failure.

Usually the pressure switch sensors are set up in the store. But if it turned out that such settings are not made, then everyone can do it themselves without much effort.

The differential pressure sensor of water is the responsible device. It must be present in each pumping station, and when installing a pump connected to a well or well, it is simply necessary. And no less responsible role in this set of equipment is the pressure sensor, because it is he who gives the pump command to switch on or off at the right time. Thus, the necessary pressure is maintained in the water supply system.

Only the correctly set limits of the greatest and smallest water pressure will allow the pump not to overheat and work intermittently, which means it will last much longer than if it worked continuously or turned off rarely.

Principle of operation

The sensor of the water pressure switch is a separate unit, hermetically sealed, in which there are springs that are responsible for the pressure limits. They are adjusted with special nuts using a wrench. The membrane transfers the force of the water pressure . They either weaken the spring (at low pressure), or keep its resistance (at high pressure).

This action of the membrane on the spring leads to connecting and opening the contacts in the pressure switch itself.

When the pressure drops to a minimum, the electrical circuit automatically closes, the pump motor is energized and turns on. The pump runs until the pressure reaches its maximum. After this, the relay will open the circuit itself and the supply of voltage to the pump stops. As a result, the pump shuts down and waits for a new command. During this time, the heated parts of the pump cool down and it does not overheat.

Typically, the water pressure sensor for the pump is set in the range from 1 to 7-8 bar. The factory setting is automatically activated at 1.5 bar (this is the minimum - the pump turns on) and 2.9 bar (this is the maximum - the pump turns off).

Pressure adjustment

Between the capacity of the accumulator, the pressure of the water pipe and the settings of the pressure sensor, there is a definite direct relationship. Therefore, before you start setting the relay, be sure to check the air pressure inside the accumulator.

Important: Before setting up, be sure to disconnect the relay from electricity.

• Drain the accumulator water;
• Unscrew the side (or bottom) cover on the accumulator;
• With the help of a car pump for tires, check the pressure - the norm is about 1.4-1.5 atm;
• If the obtained value is less, then pump up to the required level;
• If the pressure is above the norm, then "bleed" excess by pressing the tip of the nipple.

Instructions for setting the relay sensor

It is necessary to adjust the pressure switch sensor under pressure and in the running water supply system. First you need to turn on the pump so that the pressure in the system rises until the differential pressure sensor of the water is activated and the pump turns off.

Adjustment is carried out with two screws, which are installed under the cover, which closes the automation of the relay.

To change the limits of the relay sensor operation

1. Check and fix the existing switch-off and switch-on pressure when the station (or pump) is running. That is, carefully take off the manometer readings.
2. After this, disconnect the pump from electricity and, unscrewing the screws, remove the top cover from the relay and loosen the nut holding the small spring. Under it are two screws. The largest screw that is installed at the top of the device is responsible for the maximum pressure. It is usually denoted by the letter "P". Find it is not difficult. The second, smaller, is below the big screw, and its designation is "ΔP".
3. We proceed to adjust the minimum pressure. To do this, you need to release or tighten a large spring, which has the designation "P", rotating its screw on the signs "-" - decreasing (counterclockwise) and "+" - increasing (clockwise).
4. After opening the tap, lower the pressure and wait for the pump to turn on.
5. After remembering the readings on the manometer, turn off the power again and continue the adjustment, trying to reach the optimal index.
6. To adjust the shut-off pressure, you must release or tighten a small spring labeled "ΔP" by rotating its screw between the "-" and "+" signs, which indicate the difference between the switch-off and on-off pressure and are most often in the range of 1 to 1.5 bar .
7. Having switched on the pump, we are waiting for the water pressure sensor to work. If the result does not suit us, then merge the water and continue the adjustment further.

Features of the water pressure sensor adjustment

When the cut-off pressure increases, "ΔP" increases. By default, the factory settings are as follows: P on = 1.6 bar, P off = 2.6 bar with Δ = 1 bar.

You can set a differential of about 1.5 bar, setting P (off) to 4-5 bars, and P (inclusion) - about 2.5-3.5 bar. In this case, the pump will turn on less frequently, as the differential pressure increases the water pressure drop in the system. However, the cranes can react negatively to the hydraulic shock.

Adjusting the pressure limits, it is necessary to take into account the capabilities of the pump. If a value of 3.5-4.5 bar is indicated in the product passport, adjust the water pressure sensor by 3-4 bar. If you do not leave the "gap", then the overload is inevitable, and the pump motor will run constantly, without shutting down. Thus, the pressure sensor has a significant influence on the life of the pump and therefore must be constantly monitored for its condition.

If you do not change the factory settings of the sensor, you should monitor it at least once a quarter. This will prolong the life of the pump and avoid unnecessary financial costs.

Possible System Malfunctions

No pump or pump station can be operated in the absence of water. This is the most frequent reason for their malfunction, of course, if regular power outages do not occur, which negatively affects the operation of not only the pump, but also damages the water pressure sensor.

Most often the pumps use thermoplastic - plastic with increased wear resistance. Its price is low, and the benefits are obvious. However, for the system, water acts as both a lubricant and a coolant. When the equipment is operated without water, the parts quickly heat up and, as a result, they are deformed. This leads to jamming of the motor shaft, and it burns out. At best, the pump continues to operate, but does not match the specified capacity.

The most problematic use cases

• Wells and wells with a small volume of water. In this case, it is extremely important to select a pump of appropriate power and correctly adjust the water pressure sensor. This is also important because during the summer, especially on hot days, the water level in the underground sources is markedly lowered and the pump capacity can be much higher than required.
• When the pump is turned on, the water tank must be constantly monitored in order to have it switched off in time.
• In droughty periods, it is extremely important to monitor the pressure in the networked water pipe system into which the water pressure sensor is embedded in order to track the time when the pressure is gone completely.

Types of equipment and relay protection

1. Pressure sensor with protection against "dry running". In such devices, contacts are opened when the pressure falls below the set limit. Factory settings usually range from 0.4 to 0.6 bar, there is no possibility to change them. This level drops only if there is no water in the system. After eliminating the cause, the pump can only be turned on manually. However, you can use water pressure sensors. The system of water supply of this type is suitable for such a model only if there is a hydro accumulator. The use of such a relay becomes meaningless without the automatic operation of the pump. It can be used with both a downhole submersible pump and a surface pump.
2. The most inexpensive option is the float switch. It is used in systems to raise water from virtually any tank. There are also those that can only fill - rescues from overflow the opening of the contacts to stop the pump motor, and those that protect against "dry running". A cable from the float is connected to one phase, and when the water level drops below the level set in the settings, the contacts open and the pump shuts down. Therefore, the pump float should be fixed in such a way that water always remains in the vessel.
3. Flow relay with "pressure switch" function ("press control"). A compact flow switch can replace the hydraulic accumulator and the water pressure sensor in the apartment. It signals the pump when the pressure drops to a threshold of 1.5-2.5 bar. If the water does not flow through the relay, the pump shuts down. The effect is achieved with the help of an integrated flow sensor, which fixes the flow of water through the relay. Once the pump detects a "dry run", it immediately turns off. At the same time, a small delay does not affect its performance.

Select relay

When buying a relay sensor, you need to carefully study for which medium it is intended. Check the range of its settings and all additional functions, if any.

Main characteristics of the pressure switch

The following characteristics can be considered basic:

• Waterproofing;
• Simple adjustment;
• Simple installation;
• Durability and reliability;
• The contact group corresponds to the motor power.

The permissible pressure range and the manufacturer are also factors that influence the price at which the water pressure sensor in the pipeline is sold.

You can buy any brand, but to properly arrange the water supply system in a private house, it is better to instruct it to specialists.