In order for the pumping station to turn on and off as the need for water arises, a special device is built into its circuit - a pressure switch. When purchasing, the factory settings have already been set - the upper and lower limits at which the device works, but in some cases it is necessary to adjust the pressure switch of the pumping station and adjust the readings. Most often this happens in case of breakdowns in other units, clogging after prolonged operation or replacement of devices.
- Definition and purpose of the pressure switch of the pumping station
- Principle of operation and device
- When you need to adjust the pressure switch
- What pressure should be in the pumping station
- Setting and adjusting the pressure switch
- Features of adjustment "from scratch" and errors in settings
- How to avoid mistakes
Definition and purpose of the pressure switch of the pumping station
A pressure relay or sensor performs two functions in the operation of pumping equipment - when the pressure drops to the lower threshold, the electrical circuit is triggered and the device gives a signal to turn on. When the upper threshold is reached, the circuit opens and turns off the pumping station. In the factory setting, the lower threshold is set to a value between 1.5 and 1.8 bar. Top 3 - 3.5 bar. It is not recommended to change these indicators yourself without good reason.
The sensitive element of the relay is a flexible rubber membrane. When the pressure changes, this part bends in one direction or the other, which leads to the opening and closing of the contacts.
The use of a membrane relay made the operation of the pumping equipment automated, not requiring constant human intervention. In addition, the service life of pumps and compressors has increased as they have ceased to operate continuously. Overheating is the main enemy of devices, especially those that are not artificially cooled. If submersible pumps are constantly in the water column and due to this they do not overheat, then surface pumping stations fail faster and some parts have to be replaced more often.
Installing a relay is a safe operation of pipes, especially those made of relatively soft material - plastic, polypropylene. The pressure sensor keeps it within acceptable limits. With an uncontrolled rise, the pipes may burst. Moreover, a hot liquid, if it needs to be pumped through pipes or heating systems, softens the plastic and becomes vulnerable to damage. Considering that at the moment most of the water pipes are made of polymeric materials, such accidents could occur on a daily basis.
Energy saving when installing a pumping station with a pressure switch occurs automatically. If no one in the house turns on the taps, the washing machine, the toilet tank does not work, then the pumping equipment does not turn on. The signal comes when the pressure in the system drops and the device starts to work.
The specialists who created the pumping stations claim that the service life of the device does not depend on the duration of operation, but on the number of on / off cycles. If there is a large storage tank, it is possible that the station will turn on only once a day. But devices with accumulators are not the most convenient way to store water, so it was decided to equip the pump with a hydraulic accumulator, which has more advantages. The relay can be configured so that the station is switched on less frequently or more often.
Principle of operation and device
The pressure switch was invented at the beginning of the last century. Until today, its constructive scheme has changed little, and the principle of operation has not changed either.
The sensor consists of the following elements:
- contact block;
- a spring that regulates the pressure difference (lower threshold);
- large working pressure springs (upper threshold);
- place for connecting electrical wires;
- input for connecting a pressure gauge and a safety valve;
- hole for the membrane;
- on / off button;
- plastic or metal case.
In case of some breakdowns, it is necessary to replace the pressure switch, since it is impractical or expensive to repair it. To do this, you need to know how to choose the right device, because manufacturers do not always supply parts for the desired model. The policy is for people to buy a new pump, not repair an old one.
To choose a device, you need to know its type, functionality and working pressure - it is advisable not to lose the instructions for the pumping station. There are relays for water intakes, air and chemical pumping control. A pumping household station usually works with clean water, less often with sewage or dirty liquid.
The presence of protection against overheating of the electric motor may be included in the relay circuit, but this type will cost more. If possible, it is better to buy a device with protection, since the pumping station itself is much more expensive.
There is a single-phase or three-phase relay. They are used in pumping stations for dry-running protection. It is a kind of sensor that reacts to the power factor generated by the equipment. At low rates, the device turns off the pump. This is an additional feature that makes the device more expensive.
To attach a new relay to the pump, you need to know the flange size. It can be denoted by the following numbers: ¼, ½, 3/8.
Some devices have a mechanical start button. It is designed to forcibly turn on or off the pressure sensor. Other optional features include a relief valve and a setting scale.
The operating range of the pressure switch must match the required parameters of the pumping station. In the instructions, it is usually indicated by strokes.
When you need to adjust the pressure switch
If the pumping station is purchased ready-made, the factory settings are in effect. When assembling equipment manually from component parts, relay adjustment is a mandatory step before testing the device. In the operation of individual nodes, there is a relationship with the relay settings, which can interfere with the operation of the device.
Longer line lengths may require additional tightening of the large springs to increase system pressure. Some tenants who have autonomous heating and water supply installed complain about a periodic drop in pressure at the moment when a person was in the shower. The water is heated by a boiler or boiler, at the moment of pressure drop it becomes very hot. It is also related to the operation of the pumping station.
When adjusting the upper and lower threshold of the pressure switch, you need to look for the golden mean. In theory, these two indicators should have a minimum spread of values, but then the pump will turn on and off very often, which will lead to its rapid wear. If you set the lower indicator to the minimum value, and the upper one to the maximum, a sharp drop in the pressure in the system will be felt. But in this case, the pump will run longer.
Sometimes the working chamber behind the relay membrane is clogged with various deposits from the pumped water. To clean the hole, remove the rubber, turn it over with the other side and assemble all the parts in the reverse order. After that, you need to test the operation of the pumping station, check the settings and, if necessary, make a correction.
What pressure should be in the pumping station
It is believed that the pressure gauge values need to be checked and adjusted every three months.The indicators depend not only on the settings, but also on the air pressure in the tank. If the values change over time, it is not necessary to touch the relay settings, you may need to pump air into the tank using a bicycle pump. For example, the initial setting of the upper threshold was 3 atmospheres, after the volume of air in the tank decreased, the pressure gauge began to show 4 atmospheres. In this case, air is pumped into the tank.
It is impossible to make relay settings while the tank is completely filled with water. In this case, it is impossible to determine exactly how much air is in the system and how much water, because with a full tank, the total pressure is the sum of the water and air pressure.
You cannot set the upper limit for more than 80% of the maximum indicator. In this case, it is better to replace the relay or lower the upper threshold. For example, the maximum threshold is 4 bars. Taking into account voltage surges and gradual wear of equipment, including relays, the upper limit must not be set above 3.5 bar, otherwise all equipment may fail.
The smallest difference between the readings can be 0.6 bar. If necessary, you can set the pumping station to the maximum difference so that the device turns on less often.
Setting and adjusting the pressure switch
If the matter is really in the lost settings, before starting work it is necessary to prepare a wrench with which the spring will turn. It is necessary to turn on the unit and write down the indicators of the upper and lower threshold in order to more accurately determine which indicator needs to be changed and which one should be left the same.
Actions are performed in the following sequence:
- The station is de-energized.
- The water from the accumulator tank is drained and the pressure switch cover is opened.
- The closing rate is regulated by a large spring. It is usually set to 2-2.2 atmospheres. Tighten the nut clockwise until the value is at the desired figure.
- The difference is adjusted with a small spring. If it is necessary to decrease the value, the nut is turned counterclockwise, if it is increased, then it is turned clockwise.
The difference between the indicators should be optimally 1 bar, so that a change in pressure in the house is not felt.
The small spring is used to adjust the difference in indicators. It does not adjust the lower cut-off threshold.
Features of adjustment "from scratch" and errors in settings
It is much more difficult to set up a pressure switch of a pumping station with your own hands from scratch. This procedure is required when the equipment is assembled in parts and not purchased from a store. In such a situation, several parameters must be taken into account:
- air pressure in the accumulator;
- relay capabilities - its operating range;
- the length of the line and the parameters of the pump.
The lack of air in the tank will cause the membrane to immediately fill with water and gradually stretch until it bursts. The maximum shutdown pressure should be the sum of the water and air pressure in the tank. For example, the relay is set to 3 bars. Of these, 2 bars are for water, 1 for air.
How to avoid mistakes
Before increasing the pressure on the relay, you need to study the instructions for the pumping station - whether it is capable of maintaining such parameters. If not, the pump will run continuously. The relay will not shut down the system as the required pressure has not yet been reached. This situation can result in equipment burnout.
Do not tighten the nuts to the limit. This leads to a complete failure of the relay - it will stop working and automatically turn off the station.
According to the rules, the sensor is not set to maximum values. If you need to raise the upper level, it is better to buy a relay with higher maximum values. This will increase the service life of not only the sensor, but also the pumping station.
