The water supply system of the private house is impossible without a pump. But it must somehow turn on and off, make sure that it does not work in the absence of water. The turning on-shutdown of the pump corresponds to the water pressure relay, and to monitor the presence of water should protect against dry pump. How to realize this defense in different situations and we will consider further.
What is a dry pump
Where it would not rock the pump water, sometimes it creates a situation that the water is over - with a small debit of a well or well, water can be simply allocated. In case water swinging from centralized water supply, its feed can simply stop. The operation of the pump in the absence of water and is called dry running. Sometimes the term "idle move" is used, although it is not entirely correct.
So that the water supply of the house worked normally, not only the pump, but also a dry WELL protection system, automatics on-shutdown
What is bad in a dry course, except that electricity is wasting? If, in the absence of water, the pump will work, it will overheat and burn - pumping water is used to cool it. No water - no cooling. The engine will overheat and burn. Therefore, protection against dry pump - one of the components of the automation, which will have to arrive. There is, however, models with built-in protection, but they are expensive. Cheaper buy automation.
How can I protect the pump from dry stroke
There are several different devices that will turn off the pump in the absence of water:- Dry protection relay;
- water flow control devices;
- Water Level Sensors (Float Switch and Urvny Control Relay).
All these devices are intended for one - turn off the pump in the absence of water. They only work in different ways, have a different scope. Further will figure out in the peculiarities of their work and when they are most effective.
Dry protection relay
A simple electromechanical device controls the presence of pressure in the system. As soon as the pressure drops below the threshold, the supply circuit is broken, the pump stops working.
It consists of a relay from the membrane that responds to pressure and contact group, which is opened in the normal state. When the membrane pressure decreases, the membrane presses, they closes, turning off the power.
It looks like protection against dry pump
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The pressure on which the device reacts is from 0.1 atm to 0.6 atm (depending on the factory settings). Such a situation is possible when there is little water or it does not quite, the filter clouted, the self-priming part was too high. In any case, it is the condition of the dry stroke and the pump must be disconnected, which happens.
The protection relay from idling on the surface is established, although there are models and a hermetic case. It works normally in a watering scheme or any system without a hydroaccumulator. It works more effectively with surface pumps when the check valve is set after the pump.
Electrical circuit on switch protection relay from dry stroke
It is possible to put it in the system with HA, but you will not receive 100% protection from dry drum. It's all about the structure of the structure and work of such a system. Put a protective relay in front of the water pressure switch and the hydroacherumilator. In this case, there is usually the return valve between the pump and protection, that is, the membrane is under pressure generated by the hydroaccumulator. This is a regular scheme, but with this method of inclusion, a situation is possible when the pumping pump is not turned off and overheat.
For example, a dry movement situation was created: the pump turned on, the water in the well / well / no container, in the hydroaccumulator there is some quantity. Since the lower threshold of pressure is usually set about 1.4-1.6 atm, the protective relay membrane will not work - there is pressure in the system. In this position, the membrane is pressed, the pump will work dry. It will stop or when it begins or when the hydroaccumulator is spent most of the stock of water. Only then pressure will fall until critical and the relay will be able to work. If this situation arose during the active use of water, nothing terrible will not happen in principle - several tens of liters run out quickly and everything will be normal. But if it happened at night - the water was lowered in the tank, the hands were waved and went to sleep. The pump turned on, there is no signal to shut down. By morning, when the water analysis begins, it will be in a non-working condition. Therefore, in systems with hydroaccumulizers or pumping stations, it is better to use other protection devices from the dry stroke of the water pump.
Water flow control devices
In any situation, which leads to the dry move of the pump, the flow of water is insufficient or absent at all. There are devices that track this situation - relays and water flow controllers. Relay or duct sensors - electromechanical devices, controllers - electronic.Article on the topic: Installing a plinth on the floor with your own hands: Mounting methods (video)
Relay (sensors) duct
The duct relay is two types - petal and turbine. The petals have a flexible plate, which is in the pipeline. In the absence of water current, the plate deviates from a normal state, the contacts that turn off the pump are triggered.
Looking through the petals of the duct sensors
Device of a petal sensor
The device of the turbine water flow sensor
Water flow sensor for water supply
Types and parameters of water flow sensors for pump
Turbine flow sensors are somewhat more complicated. The base of the device is a small turbine with an electromagnet in the rotor. If there is a stream of water or gas, the turbine rotates, an electromagnetic field is created, which is converted to electromagnetic pulses read by the sensor. This sensor, depending on the number of pulses, includes / turns off the pump power.
Control controllers
These are mainly devices that combine two functions: protection against dry stroke and water pressure relay. Some models plus to these features can have a built-in pressure gauge and check valve. These devices are also called electronic pressure relays. These devices do not call these cheap, but they provide high-quality protection, listening out several parameters immediately, providing the pressure required in the system, turning off the equipment with an insufficient water flow.| Name | Functions | Dry protection protection parameters | Connecting dimensions | Producing country | Price |
|---|---|---|---|---|---|
| Brio 2000m Italtecnica. | Pressure switch + flow sensor | 7-15 seconds | 1 "(25 mm) | Italy | $ 45. |
| Watercolobot turbipress | Pressure relay + duct relay | 0.5 l / min | 1 "(25 mm) | 75 $ | |
| Al-Ko. | Pressure Relay + Reverse Valve + Dry Protection | 45 seconds | 1 "(25 mm) | Germany | 68 $ |
| Unit automation unit | Pressure relay + idling protection + pressure gauge | 1 "(25 mm) | Russia | $ 38. | |
| Aquario automation unit | Pressure switch + idling protection + pressure gauge + check valve | 1 "(25 mm) | Italy | $ 50. |
In the case of using the automatic unit, the hydroaccumulator is an excess device. The system works perfectly on the emergence of consumption - the opening of the crane, the operation of household appliances, etc. But this is if the reserve for pressure is small. If the gap is large, needed, and the pressure relay is also needed. The fact is that the disabling limit in the automation unit is not regulated. The pump will turn off only when it creates maximum pressure. If he is taken with a large margin in the pressure, it can create an overpressure (optimal - no more than 3-4 atm, everything that leads to premature wear of the system). Because after the automation block Press the pressure relay and hydroaccumulator. Such a scheme makes it possible to adjust the pressure at which the pump is turned off.
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Water level sensors
These sensors are installed in the well, well, capacitance. It is advisable to use them with submersible type pumps, although they are compatible with superficial. There are sensors of two types - float and electronic.
Float
There are two types of water level sensors - to fill the container (protection against overflows) and emptying - just protection against dry stroke. The second option is our first need when filling the pool. There are still models that can work and so, and the principle of operation depends on the connection scheme (in the instruction).
Principle of operation of the float switch
The principle of operation when used to protect against dry runoff is simple: while there is water, the float sensor is sick up, the pump can work as soon as the water level fell so much that the sensor dropped, the contactor opens the pump power supply, it cannot be engaged until While the water level will not rise. To protect the pump from idling, the cable float is connected to the gap of the phase wire.
Level control relay
These devices can be used not only to control the minimum water level and dry stroke in the well, well or accumulative container. They can also control overflow (overflow), which is often necessary if there is a storage capacity in the system, from which the water is then pumped into the house or when organizing the water supply of the pool.
Electrodes are lowered into water. Their number depends on the parameters that they track. If you need to monitor only the presence of sufficient water, there are two sensors. One - lowers at the level of the minimum possible level, the second is basic - located just below. The water is used in the paper: while both sensors are immersed in water, small currents occur between them. This means that water in the well / well / tank is enough. If there is no current, it means that water dropped below the minimum level sensor. This team opens the pump nutrition chain and it stops working.
The same device can control different levels, including the minimum
These are the main methods that are organized by protection against the dry stroke of the pump in the water supply systems of the private house. There are still frequency converters, but they are expensive, therefore it is advisable to apply them in large systems with powerful pumps. There they quickly pay off due to electricity saving.