Water pressure switch: what it is, how it works + how it is adjusted
Automation of independent water supply is impossible without the use of a pressure sensor. A sensitive device will almost instantly respond to a drop or increase in pressure in the network, start and stop pumping equipment without the participation of the owners.
You can use an autonomous water supply system equipped with automation devices as an urban system. It's incredibly convenient, isn't it?
We offer you complete information on how a water pressure switch works, what type of device is best to choose for installation in an independent system. Here you will find a detailed analysis of the technological nuances of various types of sensors.
The presented article has valuable information about the features of the installation of devices and the configuration of the pressure switch. For a better perception, the text is supplemented with photos, diagrams and video reviews.
The content of the article:
The principle of operation and types of pressure switches
Electromechanical models of pressure switches have been used for a very long time. They are not complicated, therefore they are reliable and easy to use. Inside the device there is a flexible plate, the position of which changes under the influence of the flow of water. The more active the flow, the greater its bend.
This element is connected to two springs that respond to a change in position of the plate. As a result, the contacts of a pair of electrical circuits operating at user-specified pressure limits are closed and opened.
One spring is set to the maximum pressure value in the autonomous network, the second - to the difference between the upper and lower pressure limits. The device is connected to accumulator.
When the pressure reaches the minimum value set for the relay, the membrane inside the hydraulic tank weakens, the contact under the second spring is activated, and the pump turns on. Gradually, the pressure rises, reaches the upper limit, after which the contact opens under the first spring, which turns off the pump.
The springs that control the contacts are equipped with adjusting nuts. With their help, you can change the compression ratio of these springs. To ensure that the device operates at a higher pressure, they are tightened more tightly, but if you need to reduce the performance - on the contrary, the element should be weakened.
This is the principle of operation of the electromechanical version of the pressure switch; newer electronic models also exist.
Electromechanical models of sensors
The operation of the pressure switch is closely connected with the accumulator, without which the inclusion of the device in the water supply network becomes meaningless. Instead of the already familiar electromechanical device, electronic options and automation units with the dry-running protection function are often used now.
If there is a risk of draining the source during the pumping process, the pressure switches are simply supplemented with an automation unit.
However, in a number of electromechanical devices, there are switch devices that can only be used with a pump. They also reduce the number of equipment starts and protect against operation when there is no water flow inside the pumping equipment.
Shutting down will help protect the motor from serious damage. In addition, using such a relay can be maintained in the water supply network. comfortable pressure.
The main characteristic of the device is the rated working pressure. It can vary from 1.5 - 6.0 bar.
When choosing a suitable relay, you should also pay attention to such indicators as:
- sizes of connecting threads;
- level of protection against dust and moisture;
- weight and dimensions of the device;
- contact voltage;
- rated current parameters;
- type of sensor, etc.
The pressure sensor can be installed directly on the hydraulic tank or mounted separately from it. It should also be noted that relays are designed to operate in a variety of environments. For household use a device designed for water.
Do not buy a relay designed for use with refrigerant or other liquids. You need to pay attention to the temperature of the working environment for a particular model.
Most often, for the needs of home water supply, the standard model RDM-5 is used. Such a device must first be connected to the accumulator of the water supply system, then to the contacts connected to the pump on / off mechanism. Then you need to provide the device with power.
Usually with pumping station a pressure switch is also supplied. If it is supposed to use an electronic model at the same time, then the shut-off pressure will be set using the electromechanical option. To connect to the water supply, use a triple fitting with suitable thread sizes.
Usually take a quarter inch element. If there is even a little experience in plumbing, this operation will take place without difficulty. Of course, all threaded connections should be sealed with FUM tape, linen thread, or other suitable material.
Complete the mechanical part of the installation of the pressure switch with the installation of a pressure gauge in order to obtain relevant information about the current state of the water supply.
During the installation of the device, you must correctly select the cable cross-section, and also ensure its grounding, using three-pin socket. If it is necessary to protect against dry running, it is necessary to ensure the correct position of the pump. It must be installed above the check valve.
After installation, adjust the water pressure switch. For this, as mentioned above, there are two screws with springs. They are under the cover that needs to be removed. In production, the device is usually set up. The standard values are from 1.4 atmospheres (minimum) to 2.8 atmospheres.
Even if these data correspond to those necessary for a particular pump, they should be checked. During storage and installation, the settings might go a little wrong. Here is the procedure for setting up a relay connected to a system with a hydraulic accumulator.
First you should measure the pressure in the tank using an automobile pressure gauge that connects to the nipple connection. The nipple is located on top on vertical models of hydraulic tanks, on the side - on horizontal, but always from the side opposite to the location of the flange.
It is better to take devices with a sufficiently high gradation of the measuring scale. Cheap Chinese models do not always meet this requirement. The tank must be left empty, the pump or station does not need to be connected to the power supply.
Normal pressure in an empty tank is set depending on its volume. Small containers (less than 25 l) should be inflated to 1.4-1.7 bar. Tanks for 50-100 liters need to be pumped up to 1.7-1.9 bar. If the pressure in the new tank does not match these parameters, you need to correct the situation, i.e. pump in the missing air or vent excess air.
Monthly it is recommended to check the condition of the accumulator, monitoring and, if necessary, adjusting the air pressure. These simple measures will not only help to maintain the required pressure level in the tank, but also prevent the rapid wear of the rubber membrane.
Before setting up, carefully read the documentation that came with the pump.
It is necessary to take into account such indicators as:
- ultimate pressure;
- operating pressure;
- water consumption rate.
This data must be used when setting up the relay, the set pressure values must be within these parameters.
The tank data is also taken into account. The power of a household pump is usually not enough to pump a conventional accumulator, but do not risk it and knowingly set incorrect settings.
Remove the cover from a relay installed in a suitable location. To do this, unscrew the fasteners. There are two springs. Next to the one that is larger, is the designation P, the one that is smaller is designated as ΔР. Now you can connect the pump or pump station to the mains, and begin the process of filling the tank with water.
When the pressure in the tank reaches the upper value, the relay will turn off the pump. The pressure gauge readings at this point should be determined. If the data obtained is different from the recommended, you need to adjust their value using a large spring.
To increase the limit, it is necessary to rotate the nut clockwise, if necessary, reduce the settings - against.
Now you should open the water and empty the hydraulic tank. Over time, the relay will trip and turn on the pump. It is necessary to again record the pressure gauge and adjust the relay settings, if necessary.To adjust the lower pressure limit, turn the small spring.
All manipulations with the adjustment springs must be carried out extremely carefully. These are very sensitive elements, you need to turn the screw gradually, to a small part of the circumference, do not make several full revolutions at once, so you can completely ruin the device.
In this case, the following important point should be taken into account: since a small nut regulates the difference between the limits, when adjusting the lower value, the data for the shutdown pressure will change.
Therefore, after adjusting the position of the large nut, wait until the tank is full and check the data for the upper limit again and change them if necessary.
When setting the upper limit settings for the relay, you need to remember that this indicator should be at least 10% lower than the pressure in the empty hydraulic tank, which was fixed and adjusted at the very beginning. Otherwise, the rubber membrane of the accumulator will be under unreasonably high pressure and will quickly wear out.
During operation, it may turn out that the recommended settings are not suitable for this particular water supply. Then you need to re-configure as described above. It should be remembered that the difference between the limits recommended by manufacturers varies between 1.2 - 1.6 bar.
But you should not be too zealous, because the greater this difference, the greater the pressure fluctuations in the water supply. The shut-off pressure should be set lower than the maximum pump pressure.
If this moment is not taken into account, the equipment will work continuously, because it will not be able to provide the level of pressure necessary to turn off the device. This situation makes using relays pointless.
Checking the settings is recommended every three months. The same operations must be performed after pump station repairreplacing the tank, etc.
Adjusting the settings is not recommended by manufacturers of systems for pumping water, but if necessary, it is better to carry out the adjustment after each new filling of the system with water, for example, at the cottage after the systems were re-milled in the spring.
For more information on adjusting the pressure switch for the pump, see this article.
Electronic relay options
Electronic models of pressure switches are an order of magnitude more expensive than electromechanical counterparts, but these costs are well worth it. Such devices are easier to configure, and the limit values can be set much more accurately.
Each such model is equipped with a flow controller, which instantly turns off the pump when there is no water. This reliably protects the pump from working in a dangerous “dry running” mode.
Typically, an electronic pressure switch is equipped with a small hydraulic tank, the volume of which is only 400 ml. It is not much, but in this way the system is reliably protected from possible water hammer network. If an expensive high-quality pump is used for the well, it makes sense to invest in a good electronic pressure switch.
Such models look quite attractive, they are highly reliable and have a long service life. But they can be sensitive to the quality of the water entering the plumbing system. To protect the relay from damage, you need to take care of the installation necessary filters.
Such devices do not have adjustment springs, so you do not have to periodically reconfigure the device due to the fact that they are weakened. And the setup itself is much simpler to perform. First you need to study the instructions.
After the first connection to the network, some models turn on with a delay of 15 seconds. This is not a breakdown, just the device is configured.
In the future, the pump can also be turned off with a delay of about 7-15 seconds. This is necessary so that the pump switches off less frequently if the pressure rises again in this short period. The electronic model of such a controller can be used in conjunction with a pump station that already has a pressure switch.
Here the upper limit is set on this built-in device. And the switching pressure is set by adjusting the electronic relay. The power is connected first to the electronic device, then the contacts are transferred to the station relay, and then the pump is powered.
If an electronic relay is connected to the accumulator, the setup is easier to perform. The lower limit is set on the relay, which should be slightly higher than the similar data indicated on the pump casing. The water flow is switched off after the maximum pressure is reached in the system, which depends on the power of the pump.
The installation location of the electronic relay is chosen between the pump and before the first point of water intake from the system. The direction of water movement indicated by the arrow should be taken into account.
If the device is used with a pump with a capacity of more than 10 atm, it is recommended to place a pressure reducer in front of the electronic relay in order to save the device from unnecessary loads.
If the existing settings are not suitable, they can be changed. To do this, tighten the appropriate screw with a screwdriver or use other settings items described in the instructions. There should be a difference of at least 0.6 atmospheres between the maximum pressure that the pump can provide and the minimum indicator of the electronic relay.
To seal the threaded connection of such a device, it is best to use teflon tape. Electronic pressure switches typically have a built-in valve. This point should be considered when emptying the water supply.
Before starting the relay for the first time, you must first fill the supply line with water, then apply power to the device, then open the tap.
The activation of the “dry running” protection mode is usually signaled by the inclusion of a red LED on the case. To reboot the system, press the “reset” button, of course, having previously eliminated the causes of a dangerous situation.
Conclusions and useful video on the topic
Setting up a standard mechanical model is presented here:
This video describes in detail the setup procedure and operating features of the electronic pressure switch using the example of the BRIO 2000 model:
Pressure switch - an extremely useful device. Once you figured out how to configure it, you can regularly adjust the pressure state in the water system and reliably protect the pump and other equipment from possible breakdowns.
Do you have any questions or is there a desire to share your personal experience in choosing, installing and using a pressure switch? Please leave comments on the article and participate in discussions - the link block is located below.