How does the water flow switch for the pump work. What are the functions of the water flow switch for pumps? Low pressure devices

The water flow sensor for the pump is an integral part of the equipment designed to protect the device from running dry. The sensor has small size and has simple design, which allows you to install it even for a beginner.

Features and Benefits of the Water Flow Sensor

Often there are situations in which the pump starts at the moment of complete absence of liquid in the pipeline. This provokes heating of the motor of the unit and its further breakdown. To avoid such situations, a fluid flow sensor should be used. This device works automatically and controls the flow of water inside the pipeline. If the amount of liquid passing through the sensor is less than the norm, the device automatically turns off the pump. Thus, the water flow switch not only prevents the pump from running dry, but also maintains normal operating conditions for the unit.

The benefits of using a sensor include:

Reducing the electricity consumed by the pump and saving money;
Protection of equipment from breakdowns;
Extending the life of the pump.

Among other things, the water flow switch for the pump is distinguished by its modest dimensions, low cost and ease of installation.

Water flow switch - principle of operation and design

The main function of the sensor is to disable pumping equipment in the event of a drop in water level or an increase in pressure in the pipeline. If the amount of water increases or the pressure drops, the liquid flow indicator restarts the equipment. Its structural elements are responsible for the stable performance of the tasks assigned to the relay.

The device device consists of the following parts:

A pipe through which liquid enters the device;
A membrane that plays the role of one of the walls of the inner chamber of the device;
Reed switch, which is responsible for opening and closing the circuit in wiring diagram pump;
Two springs of different diameters - by compressing them, the water pressure is controlled, at which the fluid flow sensor will be triggered.

The principle of operation of the relay is as follows:

When it enters the internal chamber of the device, water exerts pressure on the membrane, thereby shifting it to the side;
The magnet located on the back of the membrane gets closer to the reed switch, due to which its contacts close and the pump turns on;
If the water level drops, then the membrane with the magnet moves away from the switch, which leads to the opening of its contacts and turning off the pump.

Installing a liquid flow detector in a pipeline is quite simple. To do this, you need to study the features of connecting the device and its correct configuration.

Device connection diagram

The performance of a relay is highly dependent on its correct installation. It must be remembered that the device can only be installed on those sections of the pipeline that are located horizontally. In this case, it will be necessary to ensure that the sensor membrane is in a vertical position. Correct scheme The relay connection looks like this:

During installation, the sensor must be connected to the drain part of the pipe by means of threaded connection. The distance at which the relay must be located from the pipe must be more than 5.5 cm.

On the body of the device there is an arrow indicating the direction of circulation of the liquid. When installing the device, make sure that this arrow coincides with the direction of the water flow in the system. If used for domestic purposes dirty water, then a cleaning filter should be installed in front of the sensor.

Found the right thing to solve your problem. The tasks are:
1) In order for the watering of the garden to work or to have the opportunity to wash the car (in this case, the "pump block" should not work due to the NOT SET of upper pressure for a certain time, if it is written in the operation algorithm)
2) Have a timer to turn off after the duct is closed - shutting off the tap, airing the cold water, blockage, etc. (In the case of a dry-running relay, the question was asked - "What if the pump overtakes top pressure 2.2 instead of the prescribed 3.2 bar, if air enters the line and the relay, without seeing the lower pressure to turn off, will not turn off the pump?" Therefore need a timer to turn off the pump after flow interruption)
3) The flow sensor makes it possible to pressurize the RB. (RB is needed from water hammer and for water supply, as well as for "activating" the flow sensor, which will start the pump immediately either by timer or lower pressure)
4) The unit should not cost too much big money, since manufacturers do not have a great desire to provide warranty repairs, spare parts should also have a moderate cost.
5) The device can be restarted from a button or from a plug (socket with a switch) without running to the basement to restart the pump when the power goes out.
6) When the cold water is aired, the duct sensor cuts out the pump (in the case of watering the garden, the timer will work after the duct disappears).
Judging by the points, UNIPUMP TURBI-M1 suits me, I think it can work in conjunction with a pressure switch and these are the options for action.
I connect the wires: pressure switch + turbo m-1 + pump with RB.
At first start-up pressure = 0 bar. I fill the system with water (pump, flow switch, etc.) and open the valve to release air. The pressure switch transmits electricity to the turbo m-1, and the turbo m-1 at the first start (upon reboot) transfers power to the engine.
If I water the garden, then the pump works constantly (if the upper pressure is not reached, it will not turn off the power to the pressure switch, and the flow sensor will NOT turn off the electricity, since there is a flow). In the case when all valves are closed = no flow, pressure is built up in the RB, the pump will turn off by breaking the circuit in the event of an upper threshold from the pressure switch command, or the pump will turn off the flow sensor by timer, who will work first. It would probably be better to choose an upper pressure such that the pressure switch turns off the power earlier, well, this is just a thought.
If the power supply of the pressure switch is turned off, then the flow sensor is also de-energized. So, when the pressure drops below lower limit, let's say for a pressure switch it will be 1.8 bar, it supplies power to the flow sensor. The flow sensor (in theory), when turned on / restarted, should see this pressure and work (SUPPLY VOLTAGE TO THE PUMP) ONLY upon reaching its minimum pressure of 1.5 bar or along the flow.
It's in theory.
Further. The pressure drops (when the tap is opened) below 1.5 bar - the pump turns on at the command of the flow sensor and again everything goes in a circle.
If the light is turned off, then IF AVAILABLE required pressure in HV, the relay does not turn on the pump and the flow sensor does not turn on the pump, as there is no flow. And if the light was turned off and I bled the pressure in the cold water to zero - I wanted to get some water, then it will be possible to start this system only by resetting the flow sensor, but in fact, after turning on the light, the flow sensor should turn on by itself (as well as the pressure switch) - in fact, this restart is.
If air is leaking from the well, but the pressure switch continues to pressurize to the upper set limit, the flow sensor will cut off the power to the pump by timer. (If there is no flow and low pressure, the flow sensor will shut down the pump after 30 seconds.)
In principle, in theory, everything turns out smoothly. If I missed something, please add me.
Since the flow sensor works from two moments: when the lower threshold of 1.5 bar is reached or the appearance of a flow, I think the presence of a pressure switch will reduce the frequency of turning on the pump, so as not to drive the pump every time the tap is opened.
Z. Y. Before buying a thing, you have to run options for work and try it out on the basis of theory or people's experience.
Info on the flow sensor.

during the entire period of its operation. The installation of a flow switch in the refrigeration system is mandatory, since its main function is to protect the chiller from an emergency situation: extremely small or complete absence of liquid flow through the evaporator. This is possible in the system only in one case - when the compressor of the refrigeration machine is not running.

Flow switch - a sensor (microswitch, differential pressure switch, etc.) that signals to the chiller controller that there is a physical flow of liquid through the chiller evaporator in the heat carrier circulation system, and the flow rate through the evaporator corresponds to the nominal calculated value for the selected operating parameters of the chiller in the refrigeration system.

In practice, flow switches are used various types: mechanical and differential relays, differential pressure sensors, etc. The purpose of the devices is one - to signal the chiller controller about the normal flow of liquid through the evaporator. This determines the location flow switch- on the pipelines of the circulation circuit near the evaporator, as shown in Fig.7.

It is most advisable to install a flow switch on the pipeline at the outlet of the evaporator. A straight section of the pipe with a length of at least 10 calibers is selected and a flow switch is installed in the center of this section. It is not allowed to install a flow switch near pipe bends, shut-off valves or valves, control valves.

The body of the flow switch is mounted in a vertical position, and the direction of the arrow on the body of the flow switch must match the direction of the coolant flow. When installing a flow switch, it is necessary to provide protection contact group relay from dirt and moisture getting into the housing. It is allowed to install a mechanical flow switch on rectilinear vertical sections pipes, but only if the direction of movement of the coolant from the bottom - up.

The simplest and cheapest flow switches are mechanical relays, the principle of which is to close the contacts of the microswitch when the sensitive plate (“pen”) is turned in a moving liquid flow. The length of the plate is selected depending on the diameter of the line into which the flow switch is inserted.

The choice of the plate length is a crucial moment when installing the flow switch, since it predetermines its sensitivity. Yes, at short lengths plate contacts of the flow switch installed in the pipeline large diameter, will not close even at normal flow rates, as shown in Fig.8.

With large pipeline diameters, it is recommended to place several plates of shorter length under the sensitive plate (a kind of “spring”), otherwise the relay may quickly fail due to plate breakage at the termination point. Figure 9 shows typical practical errors when installing mechanical flow switches:

In the first case, when installing the flow switch, they “forgot” to install the plate; in the second case, the long plate "clings" to the pipe when it is turned. In the third case, the length of the plate does not correspond to the diameter of the pipeline, so the plate was installed in some arbitrary position during the installation of the flow switch; in the fourth case, the arrow on the body of the flow switch does not correspond to the direction of flow in the line.

The closing of the contacts of the flow switch when the required calculated value of the flow rate in the line is reached is regulated by a screw in the relay housing when setting up the hydraulic circuit during commissioning (see Fig. 10). If for some reason the flow rate in the line, consider in the evaporator, becomes less (G „2

In chillers, as a rule, two sequentially switched protection stages are provided for the absence or non-compliance with the calculated value of the liquid flow through the evaporator. In Fig.11, as an example, a fragment of an electric DAIKIN with a single screw compressor is shown.

The first stage is the “dry” contacts of the pump (S9L), which are closed when power is supplied to the pumping group of the circulation circuit. The signal to turn on the pumping group is sent to the controller, but this is not enough to confirm the normal flow of liquid through the chiller evaporator. For this, a flow switch is used, the closure of the contacts (S8L) of which indicates that the flow through the evaporator has reached the required value. Only then does the chiller compressor start timer start counting down and after it is reset, the compressor actually starts.

If, for some reason, the liquid flow through the evaporator has decreased or stopped altogether, the protection chain is opened and the chiller compressor stops abnormally. Modern chiller controllers record an accident, so you can easily identify the cause emergency stop(flow switch).

If necessary, the protection chain (Fig. 11) for the liquid flow through the chiller heat exchangers can be extended. So, with a water-cooled condenser, the “dry” contacts of the pumping group and the flow switch on the side are sequentially included in this chain.

When installing the equipment of the refrigeration station, it is also necessary to take into account the features of the electrical connection of the chiller and the pumping group. Power supply is recommended to be carried out separately: it is not allowed to connect the pumping group from the chiller. When starting the refrigeration plant, the pump group is always switched on first, then the chiller.

Chiller ratings (cooling capacity, power input and evaporator flow) are given in the technical data at temperature environment+35°C; the coolant of the circulation circuit is water; water temperature at the outlet of the evaporator + 7°C; water at the inlet/outlet of the evaporator 5K.

From conditions optimal performance heat exchanger- evaporator (heat exchange and hydraulic characteristics of the unit) operating temperature difference is allowed in a narrow range from 3 to 8 K. In accordance with the above, a distinction is made between:

The minimum coolant flow rate in the circulation system corresponding to the maximum temperature difference across the evaporator is 8K. This value is the lower threshold for flow in the evaporator circulation system, below which the manufacturer does not recommend the operation of the device - at such low flow rates, freezing of the evaporator channels is possible.
The nominal flow rate of the heat carrier in the circulation system corresponding to the standard temperature difference on the evaporator is 5K, the heat carrier is water. This value characterizes the stable operation of the chiller.
The maximum coolant flow rate in the circulation system corresponding to the minimum temperature difference across the evaporator is 3K. This value is the upper limit for the flow in the evaporator circulation system. A further increase in flow rate is impractical due to the deterioration of the characteristics of the evaporator due to an increase in its hydraulic resistance.
Estimated consumption coolant through the chiller evaporator, corresponding to the temperature difference on the evaporator selected when designing the refrigeration system, the chiller parameters selected when selecting equipment, the selected type of circulation circuit coolant. For standard conditions, the calculated flow rate corresponds to the nominal one.

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The water flow sensor is a device that regulates the pressure inside the water supply system. It is connected to the pumps through pipes. The main parameters of devices should include not only the limiting pressure, but also the output voltage. Manufacturers also indicate without fail throughput. Today there are many types of modifications. To understand the issue in more detail, it is worth first of all to study the device of the water flow sensor.

Model device

The standard water flow sensor circuit includes a relay and a set of plates. Inside the modification there is a wide chamber. The flask is always in a stationary state. Inside it is a small float. There is a feeding channel at the output. Many modifications are made with an adjusting tap, which is installed at the outlet. Models with valves are equipped with movable fittings. They use magnetic force to work.

Sensor: DIY

Making a water flow sensor with your own hands is quite simple. First of all, it is recommended to install the camera. A small plastic container is suitable for this. Then you will have to cut three plates that are installed in a horizontal position. The flask as a result should not come into contact with them. If we consider simple model, then one float is enough. It is more expedient to install the fitting on two adapters. The valve must withstand a pressure of at least 5 Pa.

Types of modifications

By design, only relay and fitting devices are distinguished. Additionally, modifications are separated according to the pressure level. Devices for circulation pumps are allocated in a separate subcategory.

Relay models

Relay water flow sensor for gas boiler suitable for small pumps. As a rule, models are produced with one chamber. Many experts say that they have low conductivity. However, it is worth noting that there are devices with a vertical arrangement of plates. Their limiting pressure is at least 5 Pa. Protection systems are quite often used by the P48 series. All this suggests that water leaks are rarely observed. Modifications are characterized by excellent stability. Their suction power is at least 3 N. Very rarely, models have faucets.

Union devices

The most common devices for pumps are choke modifications, which are produced with one chamber. Their plates are usually located in a horizontal position. Some modifications are equipped with two valves. And their limiting pressure parameter is approximately 5 Pa. Protection systems are quite often used class P58. In this case, the conductivity depends on the size of the fitting. Some modifications can boast high speed pumping. Connections are fairly common. threaded type. There are also clip-on sensors on the market, which are not very popular.

Low pressure devices

Modifications low pressure well suited for centrifugal pumps up to 4 kW. Their conductivity depends on the size of the chamber. The most common on the market is a water flow sensor for a two-float pump. In this case, the pumping force is on average 5 N. Protection systems are used different classes. Many sensors are installed through pads. Output contacts are designed for wire adapters. It is also worth noting that there are many inexpensive models on the market.

High pressure modifications

High pressure models are usually manufactured with one oblong fitting. The plates on the water flow sensor for the pump are most often installed in a horizontal position. If you believe the reviews of experts, then the models are great for centrifugal pumps. When choosing a modification, it is important to pay attention to the throughput of devices. The dimensions of the devices are also taken into account. Many models are made with two cameras. However, they only use one valve. If we consider standard model, then the limiting pressure averages no more than 6 Pa. The protection system in the devices is applied class P70. It is very rare to find models with a crane. Basically, ordinary switches are installed.

Devices for circulation pumps

Sensors for circulation pumps are very much in demand. hallmark modifications is considered low reducibility. The limiting pressure is on average 3.3 Pa. Protection systems are used by the most various classes. It is very rare to find devices with two cameras. When choosing a model, it is important to pay attention to the shape of the fitting. It should have a wide head and a narrow channel. Otherwise, leaks will often occur. In addition, it is worth noting that devices on floats are on the market. Their contacts are designed for adapters.

Features of models for two cameras

Sensors for two chambers, as a rule, are distinguished by large dimensions and a high pressure parameter. There are many models on the market for two valves. They have a suction force of 4 N. Protection systems are used in the P88 series. The plates of the sensors are always installed in a horizontal position. If we talk about the shortcomings of the devices, it is important to note that they use very large output channels. For pumps with a power of up to 8 kW, models are not uniquely suitable. There are devices on the market with and without taps. Additionally, there are modifications based on contactor switches.

Devices with three cameras

Sensors for three chambers are connected for centrifugal pumps. Their compressive strength is very high. It is also worth noting that the models are produced with short channels. Valves they use rotary type. They are protected by a special membrane. According to experts, the conductivity depends on the size of the chamber. If we talk about designs, it is worth noting that there are models on the market with oblong fittings. They have extremely low suction power. However, they can last a long time. In stores, devices with switches are very rare. As a rule, three-chamber models are made with small cranes.

Models for small pumps

The water flow sensor for pumps of low power should be selected only among fitting modifications. The limiting pressure indicator should be about 5 Pa. The protection system is welcome class P48. Many experts praise devices based on two cameras. Their suction force is approximately 4 N. Relay modifications for low-power pumps are not suitable in the best way.

Modifications with a vertical arrangement of plates

Devices of this type show themselves well centrifugal pumps. They have good conductivity and no problems with high blood pressure. However, do not forget about the disadvantages of modifications. First of all, they often clog the channel. If we consider an inexpensive water flow sensor, then it may have problems with the valve. For the normal operation of the system, it is more expedient to select devices with output contacts for 12 V. The protection system must be installed class P55. Experts also say that the water flow sensor should be with a contactor switch.

Devices with a horizontal arrangement of plates

The water flow sensor for this type of boiler is suitable for a wide variety of pumps. The conductivity of the models depends on the dimensions of the chamber itself, as well as the channel. Additionally, the diameter of the fitting is taken into account. Many experts recommend installing two-chamber modifications. Their pumping force, as a rule, does not fall below 5 N. The protection system is quite often used by the P50 series. All this suggests that the manufacturer guarantees a high degree of sealing and overall reliability.

When choosing a device, it is important to evaluate the parameters of the valve. If it is made of ordinary plastic, then it is not able to last for a long time. Copper counterparts perform well, but are expensive. The main flask of the sensors is made of plastic. Very rarely there are modifications with transitional contacts. Relay modifications boast high conductivity. They are not afraid of overload. And they use high-quality protection systems.

The device is intended for automatic shutdown superficial, borehole pumps, automatic water supply stations in the absence of water in the water intake systems. Switching off pumps and stations ensures their protection against damage as a result of operation without water (dry running mode). Serves to control any electric pumps operating from a single-phase 220 V network, with a power of up to 1.5 kW. The device is installed in line pressure pipeline. In this case, the pump power is connected to the device, and the power cable is connected to electrical network 220V. The place of installation of the device must be protected from the risk of water flooding, in a well-ventilated area.
OPERATING LIMITATIONS:

Temperature working environment: 0°C - 110°C
Maximum allowable pressure-6 Bar
Connection 1" (external and internal)
The maximum allowable water flow is 100 l/min

DESIGN FEATURES:

Switching voltage - 220 -240V ~ 50Hz
Maximum working current: 10A
Degree of protection - IP65
Restart - automatic
Shutdown condition - flow less than 2 l/min

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