Buy a flow sensor for a pressure boosting pump. Water flow relay - purpose, operating principle and independent connection

general description

The Grundfos UPA water pressure booster pump is a sealless pump with " wet rotor". For pumps with a “wet” rotor, the motor is completely immersed in the pumped water, which lubricates the parts and at the same time cools the engine.
The UPA pump's electric motor is cooled by the pumped liquid and, thanks to well-absorbed vibration, the pump operates silently.
The electric motor of this pump is separated from the stator by a protective sleeve made of of stainless steel. The unique ceramic bearing system gives the UPA pump unsurpassed durability and reliability.
The pumps are available in two versions:

• with a cast iron body with an internal anti-corrosion coating (UPA 15-90);
• with stainless steel housing (UPA 15-90 N).

Example UP A 15 - 90 N 160

Type range - UP
Automatic start/stop via flow switch - A
Nominal diameter of suction and discharge pipes (DN), [mm] - 15
Maximum pressure [dm] -90
Housing version - Cast iron N - stainless steel

Key Features and Functions

• Operating range Delivery up to 1.5 m3/h
• Head up to 8 m
• Supply voltage 1 x 230 V
• Temperature of the pumped liquid from 2°C to + 60°C
• Temperature environment from 2°C to + 40°C
• Max. operating pressure 6 bar
• Connection G 3/4"
• Protection class: IP 42.
• Insulation class: H.
• The pump is equipped with a cable.
• The electric motor is equipped with short circuit current protection.
• The pump noise level does not exceed 43 dB, which corresponds to EEC

Circulation pumps UPAs are designed to increase pressure in the existing water supply system of private houses, apartments, etc. First of all, they are used to create pressure in front of water heaters ( geysers And instantaneous water heaters), washing and dishwashers. Compact UPA pumps can also be used to increase water pressure in showers or other water points.
UPA water pressure booster pump are used in open systems, and can also be connected directly to the water supply network.
UPA 15-90 (N) are equipped with a flow sensor to automatically turn on/off the pump when the tap is opened at the water collection point. To provide additional protection, the electronic unit is equipped with a built-in temperature sensor. When overheating, the engine turns off; when the temperature decreases, the motor automatically turns on.
Using a switch on the terminal box, the pump is set to the desired operating mode. The small dimensions and weight of the pump allow it to be mounted directly on pipelines.

Add. Information

UPA pump design Grundfos company does not require additional effort maintenance, and will not cause difficulties in care.
The high-quality performance of pumps in the UPA model line is confirmed by certificates and has a quality guarantee.

The water supply system of a private home is impossible without a pump. But you need to somehow turn it on and off, and make sure that it does not work in the absence of water. The water pressure switch is responsible for turning the pump on and off, and the presence of water should be monitored by protection against dry running of the pump. How to implement this protection in different situation and let's look further.

What is dry running of a pump?

No matter where the pump pumps water from, at times a situation arises that the water has run out - if the flow rate of a well or borehole is small, you can simply pump out all the water. If water is pumped from a centralized water supply, its supply may simply be stopped. The operation of the pump in the absence of water is called dry running. The term “idling” is sometimes used, although this is not entirely correct.

In order for the water supply at home to work normally, you need not only a pump, but also a dry water protection system and automatic on-off switching.

What's wrong with dry running, other than wasting electricity? If the pump runs in the absence of water, it will overheat and burn out - the pumped water is used to cool it. No water - no cooling. The engine will overheat and burn out. Therefore, protection against dry running of the pump is one of the components of the automation that will have to be purchased in addition. There are, however, models with built-in protection, but they are expensive. It is cheaper to buy additional automation.

How can you protect the pump from dry running?

There are several different devices that will turn off the pump if there is no water:

• dry running protection relay;
• water flow control devices;
• water level sensors (float switch and level control relay).

All these devices are designed for one thing - turn off the pump when there is no water. They just work differently and have different areas of application. Next, we will look at the features of their work and when they are most effective.

Dry running protection relay

A simple electromechanical device monitors the presence of pressure in the system. As soon as the pressure drops below the threshold, the power supply circuit is broken and the pump stops working.

The relay consists of a membrane that responds to pressure and a contact group that is normally open. When the pressure decreases, the membrane presses on the contacts, they close, turning off the power.

This is what protection against dry running of the pump looks like

When is it effective?

The pressure to which the device responds is from 0.1 atm to 0.6 atm (depending on factory settings). This situation is possible when there is little or no water, the filter is clogged, or the self-priming part is too high. In any case, this is a dry running condition and the pump must be turned off, which is what happens.

A protection relay is installed idle move on the surface, although there are models in a sealed case. It works normally in an irrigation scheme or any system without a hydraulic accumulator. Works more efficiently with surface pumps, When check valve installed after the pump.

When it does not guarantee shutdown in the absence of water

You can install it in a system with HA, but you will not get 100% protection against dry running of the pump. It's all about the particular structure and operation of such a system. Place a protective relay in front of the water pressure switch and the hydraulic accumulator. In this case, there is usually a check valve between the pump and the protection, that is, the membrane is under pressure created by the hydraulic accumulator. This usual scheme. But with this method of switching on, it is possible that a working pump in the absence of water will not turn off and will burn out.

For example, a dry running situation has been created: the pump is turned on, there is no water in the well/borehole/tank, and there is some water in the accumulator. Because lower threshold the pressure is usually set to about 1.4-1.6 atm, the protective relay membrane will not work. After all, there is pressure in the system. In this position, the membrane is pressed out, the pump will run dry.

It will stop either when it burns out or when most of the water supply is used up from the hydraulic accumulator. Only then will the pressure drop to critical and the relay will be able to operate. If such a situation arose during the active use of water, nothing terrible will happen in principle - several tens of liters will dry up quickly and everything will be normal. But if this happened at night, they flushed the water in the tank, washed their hands and went to bed. The pump turned on, but there was no signal to turn off. By the morning, when water collection begins, it will be inoperative. That is why in systems with hydraulic accumulators or pumping stations It is better to use other devices to protect against dry running of the water pump.

Water flow control devices

In any situation that causes the pump to run dry, there is insufficient or no water flow. There are devices that monitor this situation - relays and water flow controllers. Flow relays or sensors - electromechanical devices, controllers are electronic.

Flow relays (sensors)

There are two types of flow sensors - petal and turbine. Petal has a flexible plate that is located in the pipeline. In the absence of water flow, the plate deviates from normal condition, the contacts are activated, turning off the power to the pump.

Turbine flow sensors are somewhat more complicated. The basis of the device is a small turbine with an electromagnet in the rotor. When there is a flow of water or gas, the turbine rotates, creating an electromagnetic field, which is converted into electromagnetic pulses read by the sensor. This sensor, depending on the number of pulses, turns on/off the power to the pump.

Flow controllers

Basically, these are devices that combine two functions: dry-running protection and a water pressure switch. In addition to these features, some models may have a built-in pressure gauge and check valve. These devices are also called electronic relays pressure. These devices cannot be called cheap, but they provide high-quality protection, serving several parameters at once, ensuring the required pressure in the system, turning off the equipment when there is insufficient water flow.

In the case of using an automation unit, the hydraulic accumulator is an extra device. The system works perfectly when flow appears - opening the tap, triggering household appliances and so on. But this is if the pressure reserve is small. If the gap is large, both a HA and a pressure switch are needed. The fact is that the pump shutdown limit in the automation unit is not adjustable. The pump will turn off only when it has created maximum pressure. If it is taken with a large margin of pressure, it can create overpressure(optimal - no more than 3-4 atm, anything higher leads to premature wear of the system). Therefore, after the automation unit there is a hydraulic accumulator. This scheme makes it possible to regulate the pressure at which the pump turns off.

Water level sensors

These sensors are installed in a well, borehole, or container. It is advisable to use them with submersible pumps, although they are compatible with surface pumps. There are two types of sensors - float and electronic.

Float

There are two types of water level sensors - for filling the container (protection against overflow) and for emptying - just protection against dry running. The second option is ours, the first is needed when filling out. There are also models that can work either way, but the principle of operation depends on the connection diagram (included in the instructions).

The principle of operation when used to protect against dry running is simple: as long as there is water, the float sensor is raised up, the pump can operate, as soon as the water level has dropped so much that the sensor has dropped, the contactor opens the pump power circuit, it cannot turn on until until the water level rises. To protect the pump from idling, the float cable is connected to the open phase wire.

Level control relay

These devices can be used not only to control the minimum water level and dry running in a well, well or storage tank. They can also control overflow (overflow), which is often necessary when there is a storage tank in the system, from which water is then pumped into the house or when organizing a water supply for a swimming pool.

Electrodes are lowered into the water. Their number depends on the parameters they monitor. If you only need to monitor the presence of a sufficient amount of water, two sensors are enough. One - goes down to the level of the minimum possible level, the second - basic - is located slightly lower. The work uses the electrical conductivity of water: while both sensors are immersed in water, small currents flow between them. This means that there is enough water in the well/well/container. If there is no current, this means that the water has dropped below the minimum level sensor. This command opens the pump's power supply circuit and stops working.

These are the main ways in which protection against dry running of a pump is organized in the water supply systems of a private home. Is there some more frequency converters, but they are expensive, so it is advisable to use them in large systems with powerful pumps. There they quickly pay for themselves due to energy savings.

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

Features and Benefits of Water Flow Sensor

Situations often arise in which the pump starts when there is a complete absence of liquid in the pipeline. This provokes heating of the unit’s motor and its further breakdown. To eliminate 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 normal, 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 advantages of using the sensor include:

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

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

Water flow switch - operating principle and design

The main function of the sensor is to turn off pumping equipment in case of a decrease in water level or increase in pressure in the pipeline. If the amount of water increases or the pressure drops, the liquid flow indicator starts the equipment again. Its structural elements are responsible for the stable performance of the tasks assigned to the relay.

The 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 internal chamber of the device;
• Reed switch, which is responsible for opening and closing the circuit in electrical diagram pump;
• Two springs of different diameters - by compressing them, the water pressure is controlled, at which the liquid flow sensor will be triggered.

The principle of operation of the relay is as follows:

1. When water enters the inner chamber of the device, it puts pressure on the membrane, thereby moving it to the side;
2. Located with reverse side membrane, the magnet becomes closer to the reed switch, which causes its contacts to close and the pump to turn on;
3. If the water level drops, the membrane with the magnet moves away from the switch, which opens its contacts and turns off the pump.

Installing a liquid flow indicator into 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 operating efficiency of a relay greatly depends 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, you will need to ensure that the sensor membrane is in a vertical position. The correct relay connection diagram looks like this:

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

There is an arrow on the body of the device indicating the direction of liquid circulation. When installing the device, you need to make sure that this arrow coincides with the direction of water flow in the system. If dirty water is used for domestic purposes, then cleaning filters should be installed in front of the sensor.

Flow sensor- a device that generates an output signal in the presence of a flow of liquid or gas. They are installed in pipelines and air ducts where the presence of working fluid flow is a critical parameter.

This sensor is also called flow switch, because its principle of operation is similar, with the only difference that its operation is caused not by the appearance of a control voltage on the coil, but by the presence of a flow of liquid or gas. But the result of triggering the flow sensor, as well as a conventional relay, is a change in the state of the output contacts to the opposite.

As a rule, the sensor has a normally closed (NC) and a normally open contact (NO). When a flow of working medium appears, the NC contact opens and the NO contact closes.

There are several types of flow sensors:

Petal flow switch

The figure shows a diagram of a petal-type flow sensor.

As the name suggests, the main working element of this type of flow sensor is a flexible petal that is in contact with working environment and deviates from the vertical position in the presence of flow. The petal is mechanically connected to the output contacts and changes their state when it bends itself.

Caleffi (left) and Danfoss (right) petal flow switches

Turbine type flow sensor

The figure shows a diagram of a turbine-type flow sensor.

Such sensors are a small turbine whose rotor is equipped with a magnet. When a flow of working substance passes through the device, the turbine begins to rotate, resulting in a magnetic field that is converted into electrical impulses, arriving at electronic circuit sensor The electronics cause the output contacts to change state when flow is present, just as in a paddle sensor.

Thus, such flow sensors have two types of outputs: output contacts (NO and NC) and pulse output. The latter is used to determine the flow speed: the higher the pulse repetition rate, the higher the flow speed.

Flow sensor (turbine) for Ariston boiler

An example of this type of sensor is a flow switch gas boiler Ariston. When flow appears (when the user opens the tap hot water), the sensor generates an output signal and switches the boiler to DHW heating.

Using Flow Sensors

Flow sensors most often perform protective, informational or control functions.

The protective function is associated with detecting the presence of flow in systems where its absence can lead to emergency situations or equipment breakdowns. For example, they protect pumps, because When operating in the absence of water flow, they overheat and fail. You can also determine the lack of air flow in ventilation systems when the filter is clogged, the damper is closed, or the fan breaks down. Using a flow switch, you can detect leaks in water supply systems, determine the lack of water in storage tank etc.

The information function of a flow relay is spoken of when the presence or absence of a flow is not associated with emergency, but is a significant event in the system that the user needs to know about. In such cases, the sensor is used to trigger a light or sound indication, or generate a message on the operator panel.

The flow switch performs the control function when other equipment is turned on or off based on its signal. For example, in DHW systems when the user opens the tap with hot water, the gas boiler must turn on the pump and switch to the DHW heating mode. This happens just when the flow sensor is triggered after opening the tap.

Flow switch connection diagram

The following figure shows typical diagram turning on the flow sensor for the pump.

If there is no flow, NO contact 1-2 is open, and NC contact 1-3 is closed, the power circuit is open, and the pump is stopped. When a flow of water appears through the relay, its contacts change their state, the power supply circuit of the pump is closed and it turns on.