Pressure switch for the compressor with his hands

Automatics for compressor

Compressor equipment. an indispensable attribute in every house, country house and most city apartments. To keep it running accurately, smoothly and at full capacity, while avoiding maximum wear and tear, you need a quality compressor automation. What it is, what it consists of and what it is used for? Like any automatic devices, compressor automatics is called upon to control without human intervention the incoming parameters in the system, switching on at their certain values the corresponding functions of the equipment. It consists of a pressostat and a control and dispensing unit for the compressor.

Pressostat (pressure switch). is a basic component of compressor automatics

The main function of the pressostat. proper starting and stopping of compressor equipment under specific parameters of air supply. As soon as critical values of air pressure level are reached, occurs:

Motor activation (if the pressure is high enough);

system shutdown (at low pressure).

Thus, the pressostat for the compressor, which is often called in the home “air pressure switch”, regulates the starting and stopping process, preventing the compressor from operating in conditions of excessive wear and tear. these are. important, because wear and tear on the equipment would occur not just an order of magnitude more often, but at times, and even dozens of times in some cases. That is why, among compressor automatics, the price of complex pressostats is higher than that of other mechanisms. In such equipment there is not just an air pressure switch for the compressor, but also additional auxiliary elements:

A pair of pressure gauges (round instruments with a scale of pressure units);

supply lines (tubes and two nozzles);

There is a hole in the relay, closed by a special valve. Its task is to. open to bleed air from the compressor after the equipment has been shut down. Then there will be no residual air in the tubes at the next start-ups, which helps avoid exceeding the allowable pressure in the system for its normal start-up. There is also a pressure switch for the compressor. It enables closing of contacts (or, conversely, opening of contacts). and, as a consequence. Starting or stopping the compressor engine. You can buy a pressure switch for a compressor in most online stores of tools and equipment for home and work. But do not forget to ask beforehand about reviews of those who have already purchased similar products, as well as get detailed advice from an expert on compressor automatics or master of installation of this equipment. A quality pressostat will allow without your participation to adjust the work of the compressor in conditions of inconsistent pressure and ensure smooth and uninterrupted operation of the system.

Compressor control switch unit

The essence of the control-distribution unit is already reflected in its name. In other words, this position of automatics for the compressor has only two tasks:

Control of level of air pressure fed into the system;

its adjustment up to the parameters necessary for the start of the compressor engine and its stable functioning.

The unit itself with pressure regulator for compressor. is a kind of valve that closes or, on the contrary, opens a hole in a pipe to the required level, regulating in such a way the air inflow and thus the pressure. By turning the valve to the right or left it is possible to change the volume of air supply. The control-distribution unit weighs about 250-350 grams and is relatively inexpensive by its cost. But without it, you can incur considerable financial and time losses, especially if you allow the total failure of the compressor.

As a rule, most of the compressor automatics operates on 220V line, but there are also devices for 380V line. At the same time there are no noticeable differences in them, the absence or presence of additional units and assemblies. Therefore, when buying an automatic control for the compressor on any of the Internet resources, stores or markets in Ukraine, find out in advance all the necessary nuances for your communications. Then you won’t have to waste time and effort replacing and reinstalling equipment. We wish you a pleasant shopping experience, exceptionally profitable investments and quality, long-lasting and uninterrupted operation of the automatic devices for compressor and other equipment for home and country houses!

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Relay structure and diagram

Compressor relays are divided into two types: normally open and normally closed. The first ones switch on the compressor when the air pressure exceeds a certain level, and the second ones switch on the compressor when the pressure falls below a certain level.

Pressure switches act as an actuator element, the compression force of which is changed by a special screw. Usually the compression force of the springs is set to 6 atmospheres, as specified in the user manual. Since the stiffness and flexibility of the spring-type elements depend on the ambient temperature, all compressor pressostat designs are designed to operate in the range of.5 to 80 degrees.

Two essential sub-assemblies of this relay: the unloading valve and the mechanical type switch. The first one is connected to the air line located between the air receiver and the compressor. It controls the motor. At switching-off of compressor drive such valve releases 2 atmospheres of compressed air into environment, unloading movable elements of compressor from excessive force. This is the force that must be exerted when the compressor is switched on again. It prevents the motor from being overloaded in terms of torque limit. When starting an unloaded motor, the valve closes without placing undue load on the actuator.

Features of pressostat

The mechanical switch has a “stand by” function. It prevents accidental start of motor. The pushbutton activates the drive and the compressor runs automatically. At the moment of shutdown, the compressor motor will not start even if there is a small amount of atmosphere in the pressure-type pneumatic system.

Safety is increased by equipping industrial designs of pressure switches with a fuse in the form of a valve. It is very useful in case of an unexpected motor stop, piston failure, or other emergency situation.

Sometimes the pressostat housing has a thermal relay inside to check the primary current. If this parameter begins to grow, then to prevent overheating and the following breakdown in the windings, such a relay will shut down the motor.

Tips for selecting the part

When choosing a check valve for the compressor one should know the size of threads cut on the cylinder outlet. Threads can vary from unit to unit. It is easier to take the defective part with you and choose the analogous one in the store.

If you need to replace the return valve, for example, with a more reliable model, familiarize yourself with the specifications of the new part. Some of them are not designed to work with high-pressure compressors. Usually the maximum pressure at which it will be able to work is indicated on the package to the return.

Also the temperature characteristics of this node should be taken into account. If the air after compression is heated to high temperatures, you should not buy a plastic unit. Preference should be given to a metal check valve that is installed inside the duct.

Pressostat for the compressor: independent connection and adjustment

In most cases, inexpensive models of air compressors are not equipped with a pressure switch, because such products are mounted on the receiver. On this basis, many manufacturers think that the visual control of pressure by means of a manometer will be more than enough. However, during prolonged use of the device, if you do not want to bring the engine to overheat, it makes sense to install a pressure switch for the compressor! With this approach, shutdown and startup of the drive will be automatic.


Operation of any air compressor involves obtaining a jet of air. It must be of a certain pressure and must be uniform and stable. It must be possible to change the parameters of the air jet. Any compressor has an air reservoir (capacity in the form of a cylinder). It must have the required pressure. If it begins to fall, the engine needs to be started and the used air replenished.

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How to adjust compressor air pressure switch/paano mag adjust ng pressure ng compressor

If the pressure has become excessive, the supply of the air mass must be stopped. Otherwise, the tank will simply burst. It is the relay and the pressure regulator that controls this process. Proper operation of this mechanism ensures the safety of the engine, protects it from frequent switching on and off, and makes the system work evenly. The tank diaphragm is structurally connected to a relay switch. As it moves, it turns the relay on or off.

Methods of repair

The solution to a more difficult problem will be, if the compressor does not work. There could be several sources. Consider one of them. melting of pressostat contacts because of erosion caused by electric sparks.

To fix this kind of failure, you can use one of the following ways: clean the surface, which will prolong the life of at least 3 months, or repair by replacing the contacts in the terminal clamps.

  • Bleed all the air from the air reservoir and cut off power to the ejector. Remove the pressure switch.
  • After removing the protective case, disconnect the wiring to the contact group.
  • Use a screwdriver to remove the terminal with contacts and drill out the burnt lines.
  • The wire can be replaced with a copper wire. Choose one based on the diameter of the hole, i.e. к. it should fit tightly in the seat. It is inserted into the hole and crimped on both sides.
  • Do the same with the rest of the burnt lines.
  • After the contact group is assembled, it is mounted in its original place and the pressostat cover is screwed on.

Compressor relay functions in difficult conditions, subject to wear and tear and failure.

Although the repair is not cost-effective, those who are familiar with the device can do it themselves. However, it is still advantageous to replace it with a new unit.


The function of air compressors is to get a stream of air with a certain pressure, it must be stable and uniform. It should also be possible to change the parameters of this jet. Each compressor has a reservoir (cylinder) for air. It must have the necessary pressure. When it goes down, the motor must be turned on to replenish the air supply. If there is too much pressure, the air supply must be cut off so that the container does not burst. This process is controlled by the pressure switch.

The design of the pressure switch RDM-5

If it functions properly, the motor is preserved, it is protected from frequent switching on and off, and the operation of the system is uniform and stable. The capacitance diaphragm is connected to the pressostat switch. By moving it, it can turn the relay on and off.

Operating principle

Considering the pressure value in the system, the relay is used to open and close the voltage circuit, starts the compressor when the pressure is insufficient, and turns off when the parameter rises to a predetermined value. This is the principle of a normally closed loop for control of the motor.

Also encountered is the reverse operating principle, where the relay turns off the electric motor at the minimum pressure in the circuit, and at maximum pressure. it turns on. This is a scheme of a normally open circuit.

The working system is the springs of different stiffnesses, which react to changes in pressure. During operation, the forces of spring deformation and compressed air pressure are compared. On change of pressure, the spring mechanism turns on and the relay closes or opens the circuit.


The air compressor relay may contain the following components:

  • Relief valve. Located between the compression and check valves on the compressor. When the engine is stopped, this component trips and relieves excess pressure from the piston unit. When the engine starts, the pressure created closes the valve, this makes it easier to start the unit. Some unloading valves have a delayed actuation. When the engine starts, it assists the engine by staying open until the set point is reached in the system. During this time, the motor reaches maximum speed.
  • Mechanical switch. Serves to switch the automatics on and off. The switch usually has two positions. When the automatic mode is activated, the compressor is plugged in and turned off based on the specified pressures in the system. The drive is not energised in the de-energised position.
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Pressure switch for air compressor

The engine won’t start: what to do?

When the motor does not hum or start, it may mean that there is no supply voltage. A small screwdriver can be helpful in checking for “phase” and “zero” contacts. You should also pay attention to how securely the plug is connected to the socket. If the contact is bad, you need to make a tighter fit.

If there is nothing wrong with the input power, it is necessary to check the fuses of the compressor. To replace failed fuses, devices of the same rating are used.

Never install fusible plugs, which have a higher amperage rating. If the fuse blows again, find out what caused it, there may be a short in the circuit input.

pressure, switch, compressor

The machine can also fail to start for another reason: level settings can be confused or there can be a fault in the pressure control relay in the receiver. In order to check this, you need to flush the cylinder gas and test run the blower. If the engine starts, it is necessary to reset the relay. If not, it is necessary to replace the faulty part.

homemade compressor!

I want to share another self-made device, the idea of which was based on the articles from the great and powerful “Internet. Once I saw a homemade compressor from a fire extinguisher, I got the idea, and for a long time (t.к. There was no urgent need) assembled components. Which include:

Refrigerator motor is the compressor!

pressure, switch, compressor

Pressure switch. turns the motor on and off.

Pressure gauge. to read pressure in air reservoir.

Pressure reducer. so that the outlet air flow is uniform and can be adjusted.

Moisture separator. Separates condensate as air is cooled by compression. And the water when working with an airbrush, for example, can cause a lot of trouble.

All kinds of tees, couplings, adapters, etc.д. and t.п. Since the connection scheme of the compressor is not standardized and you can use a lot of options.

Unfortunately there are no pictures of the step-by-step assembly. But at the end result is visible that to what connected and how!

This option is not finished yet because under it will be welded to a framework of pipes 15×15 mm.

My version of the compressor was made for airbrush. Its working pressure of about 2 bar. So I had enough reagent can for the receiver (its maximum pressure is 3).2 bar).

The motor is connected through a switch (so as not to run to the socket), from the pressure switch. At the tube, sucking air put coarse filter (gasoline). Air tube connect to the receiver. The third tube. to replace the engine oil, must remain sealed if not close it with a plug.

At the outlet of the receiver put pressure reducer to reduce the pressure, after him the filter water separator. All you can do is plug in the airbrush and go! In my case learn! In someone else’s already creating!

pressure, switch, compressor
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