How to build the check valve for the compressor

check valve

A non-return valve (check valve) is a device that allows compressed air to pass only in one direction. It is assembled structurally (Ref. fig.) in a metal housing (pos. 3), inside which are placed:

  • internal shutter (pos. 6) covering the inlet opening;
  • spring (pos.4), pressing the rubber ring (pos.5) to the plug seat;
  • inlet connection (pos.7);
  • plug (pos.1) with cardboard gasket (pos.2) (the plug makes it possible to disassemble the returner for repair or maintenance).

For your information! The check valve has a branch to connect it to the receiver and a small branch to connect the pressostat.

Operating principle

The reverse acting valve works in the following way. Compressed air passes through piston cylinder outlet valve and enters through inlet fitting (pos. 3) into receiver.7). On reaching a certain pressure the air lifts the internal plug (pos.6) and through the cavity in the housing (pos.3) passes through into receiver storage tank. When the compressor is switched off the spring (pos.4) Returns the inner bolt into place, blocking the air from the receiver back to the piston cylinder.


In the domestic market you can find compressors with check valves made of three different materials: aluminum, plastic and brass. The aluminum part is distinguished from its counterparts by its high reliability and long service life. It is built into the ducting that connects the piston cylinder to the receiver, and is capable of operating under high temperature conditions (up to 200°C). Whereas plastic check valve is used in low cost models working at low medium temperature. As to valves that are made of brass they are widely used. Such check valves are sufficiently reliable and maintain their operational characteristics perfectly when the temperature of air at compression does not exceed 140°C.

Selection recommendations

If the compressor check valve is out of order it is not difficult to replace it with a similar one. However, before you buy a new valve, you should pay special attention to the diameter of the threads cut on the outlets of its body. In fact the connecting sizes of the check valve, the compressor and the receiver can differ from each other.

Tip! Going to buy a new check valve for the compressor do not forget to take with you the defective part. It will considerably facilitate the procedure of selection of a new assembly.

It is also necessary to take into account the technical characteristics and operating conditions of the compressor. After all, there are valves that are not designed to work with high-pressure compressor equipment. over, when the working medium heats up to high temperature during compression, plastic return pipes are not reasonable. it is better to buy a unit in a metal case that is installed inside the air pipe which connects the compressor and receiver. It will not be superfluous and purchase of demountable construction. it will allow in the future to buy the appropriate repair kit and to correct malfunction of the return independently, replacing the failed parts with purchased spare parts.

Making a check valve with their own hands

In cases where buying a new check valve to replace a failed one is not possible, you can make it with your own hands from improvised materials. For this you will need:

  • T-piece with an internal thread;
  • spring;
  • 2 sockets with male thread, the diameter corresponding to the internal thread of the tee;
  • A ball with a diameter larger than the size of the inner hole in the socket;
  • a metal plug with an external thread that matches the internal thread on the tee.
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Assemble the valve in the following sequence: first the socket is screwed into one of the branches of the tee, then from the other side the ball is inserted into the tee, and then the plug is screwed in, pressing the ball with a spring.

There are some practical tips for making a retractor.

  • It is better to take the ball from an old computer mouse. it has a rubberized surface that will stick tighter to the edges of the hole.
  • An ordinary piece of pipe of suitable diameter can also be used as a body. True, in this case it will have to drill a hole in her side, weld another branch and at all ends of the thread.
  • The spring should press the ball with a certain force and under no circumstances should be loose.

Main varieties

The examined receiver valve can be classified by quite a large number of features, but the main thing is in the design features of the mechanism. The following variants of design are distinguished:

  • Angular.
  • Straight type.
  • Ball type.
  • Spring-loaded.
  • Flanged.
  • Sash type.
  • Installed by using soldering technology.
  • made under flanging.

Classification is performed by the type of material used in the manufacture. Most often the valve is made of metal with high corrosion resistance, but there are other versions.

The locking element is also characterized by different design features. According to this feature, the following design variants are distinguished:

Rather popular are ball-type versions. This is due to their practicality and high reliability in use.

In addition, on sale there are versions of performance, in which the control of the blocking element is represented by an electromagnetic element, but not a spring. They are more precise in operation but are much more expensive.

Compressor is heating up too much

If the compressor is warming up a lot, it signals some kind of malfunction. There could be several causes for overheating. Starting with a simple one, it is blocked air blowing to the cylinder and crankcase. Check if the impeller is blocked by foreign bodies.

One of the primary causes of a warming compressor is a lack of oil level. Working parts are worn out, high friction is created and as a consequence, it gets very hot. Continued operation in this manner will result in rapid failure of the equipment. Check the oil level; if it’s not enough, it needs to be topped up to the proper level.

Faulty valves, as a result of carbonised contamination or looseness. There can also be clogged air ducts.

Check the pressure level. Maybe the automatic system is broken and the compressor is “hammering” to a high pressure and this causes overheating. Repair or replace safety valve might be necessary.

The compressor (motor) will not start

Compressor does not turn on, the most common fault. The main and trivial thing that can be in this failure is no voltage in the network. The first thing to check is the plug and wire breakage that feeds the motor. Use special “tester screwdriver” to check that all phases are energised. Check the fuse, if one is present. Check the serviceability of starting capacitors (single-phase compressors have 220V voltage).

Pay attention to the pressure in the tank (air reservoir). Perhaps the pressure is sufficient and the automation does not start the compressor as soon as the pressure falls to a certain level, the motor will start automatically. This is not a malfunction, many people forget about this nuance and worry about it prematurely.

A check valve can also be a problem if the compressor does not start. Also faulty block of automatics (presostat), influences on breakage (on/off), the button on the block itself may have become useless.

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If the electric motor does not start humming, buzzing, does not pick up the necessary speed or stops during operation, it does not always mean that it is broken.

Main malfunctions of electric motor which can prevent it from operating correctly

  • Low motor supply (insufficient mains voltage)
  • Loose connections, poor contact
  • Check valve has failed (leaking), thereby creating back pressure
  • Improper compressor start-up (see operating instructions)
  • Piston unit jammed (due to insufficient oil level, overloading)

If the electric motor of the compressor does not start at all and does not make a sound, it testifies about the following:

  • The power supply fuse has tripped
  • Overload protection has tripped
  • Bad contact in the electrical circuit (malfunction of electrical wiring)
  • The worst, the electric motor burned out (often there is a characteristic smell)

Non return compressor valve: device, function, types

Today, in order to guarantee the smooth operation of compressor units, used almost everywhere, use a number of additional technical mechanisms, one of which is considered a check valve for the compressor. Such a valve, which is used in many compressor units, also protects them from early failure and ensures silent switching on.

Main varieties

Check valve systems, depending on their design, can be:

check, valve, compressor
  • of the direct type;
  • Angular;
  • spring-loaded
  • ball-type;
  • flange mounted;. spring mounted;
  • flap valves;
  • solder-mounted;
  • made to fit the flange.

Check valve. straight type for high pressure stations

The material of manufacture may also vary, depending on what media such a device will be in contact with in operation. In particular, it can be both metal alloys of various types and plastic.

Depending on the type of shut-off element used check valves can be:

  • with an isolating element in the form of a flat valve;
  • ball valves;
  • diaphragm valves;
  • paddle-shaped;
  • with a gravity grid.

The last three types are used for installation in ventilation systems. Among check and safety valves installed on compressors, ball-type devices are the most popular because they are less critical to contaminants present in the working environment.

Check valves with cone (a), flat (b) and spherical (c) shut-off elements

Among the most modern check valve systems are electromagnetic type, in which the movement of the valve is not controlled by a spring but by a solenoid. Meanwhile, due to the rather high cost and not much reliability such devices are not very popular, yielding to cheaper and time-tested spring counterparts.

Types of pressure relief valves

According to the method of pressing the shut-off element to the seat, the devices are divided into the following types:

  • Sprung. The resilient deformation force of the spring metal holds the shutter closed. It is selected in such a way that the pressure exceeding the preset level presses the shut-off element from the seat. Spring loaded models are available with both fixed and adjustable actuation pressures. For this purpose, an adjusting screw is added to the construction, pre-compressing or loosening the spring. During use, the spring gradually loses its elasticity, and the actuation value may change.
  • Lever-loaded. To clamp down, the force of gravity is used, acting on a weight suspended from the end of the lever. This system has a wide range of options for adjusting the actuation value. To increase it, the load is moved to the end of the lever, to decrease it, closer to the body. Apart from the fine tuning capabilities, this design also has the advantage of stable reset pressure values over long periods of time. Lever arm units are large and heavy. It is used as a pressure relief valve for stationary large capacity compressors.
  • Electromagnetic. These leading edge devices use an electromagnetic actuator, a solenoid, to press the locking element. These devices function as an actuator in a centralized automated control system. The pressure sensor can be located next to the plug or in a completely different part of the system. Most of them are additionally equipped with an operating spring. In case of loss of power supply or communication to the control system, the reset valve becomes a conventional mechanical reset valve.
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Bleeding valves are divided into the following types according to the way they are connected:

  • Threaded. The most common type for low pressure relief devices. Easy to mount and dismount even for untrained personnel. only a wrench is needed. Most often used as an emergency valve of a mobile compressor of small capacity.
  • Flanged. difficult to install and more expensive, they have a high leak-tightness. are used in medium and high pressure systems.
  • Welded. For maximum tightness and reliability. Difficult to assemble/dismantle, special equipment and trained personnel are required.

According to the material from which the device is made, distinguish:

Quick & Easy DIY one-way/check valve from 1/4 NPT Air quick coupler

  • Steel. They have high strength and long service life. Withstand high pressure.
  • Brass. High corrosion resistance and long service life.
  • Plastic. Cheap, but designed for low head values.

Part selection tips

Choosing a check valve for the compressor, it is necessary to know the size of threads, cut on the outlet of the cylinder. Threads can be different on different models of units. It is easiest to take the defective part with you and choose a similar one in the store.

If it is necessary to change the checker, for example, for a more reliable model, one should read the specifications of the new part. Some of them are not designed to work with high-pressure compressors. The maximum pressure at which the return valve can work is usually marked on the package.

You should also consider the temperature characteristics of this unit. If the air after compression is heated to high temperatures, you should not buy a plastic unit. Preference should be given to the metal check valve, which is installed inside the duct.

Why do you need a pressure relief valve

This device is designed to protect the system from overpressurization. The emergency valve is actuated when the pressure exceeds the threshold value, opens and releases some air into the atmosphere. In this case, the pressure is reduced to normal pressure and the pressure relief valve closes.

check, valve, compressor

When the compressor stops, compressed air remains in the compressor cylinders. Relief valve is triggered when the engine is shut down, venting to atmosphere.

If this is not done, restarting the machine is difficult or even impossible.

In addition, storing a compressor without excessive cylinder pressure increases compressor life.

An air vent valve is essential on a compressor in case the pressure switch on the compressor fails.

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