Compressor outlet pressure regulation. Purpose

Pressure switch for the compressor: device, marking, wiring diagram and adjustment

Using the air pneumatic relay allows for automatic filling of the compressor’s receiver with compressed gas. The operator of a machine with a pressostat does not need to monitor the process, trying to fix preset limits. As a result, motor failure is prevented. Substantial results, aren’t they??

If you are planning to buy a pressure switch for a compressor, you’ve come to the right place. We have a wealth of extremely useful information about the operating principles of the unit, how it is equipped and how it is connected.

We described in detail the existing types of pneumatic relays. Connection options to the domestic and industrial network with very clear layouts. We have disassembled typical breakdowns and ways to prevent them. We have presented information and helpful hints in addition to graphical, photo and video applications.

How to configure the compressor

StarKraft makes every effort to ensure that compressors purchased or serviced by us are operating at peak performance. This result can only be achieved by taking an integrated approach at each stage.

From model selection, through documentation, installation, commissioning and start-up to start-up, every little detail is important. Proper compressor tuning is also very important.

It is best if each step will be performed by experienced, qualified employees of our company.

Fulfillment of all service requirements is the key to a long life of the equipment. In this article we will look at what is primarily affected by the correct setting of the air compressor. On this subject, you can always consult an employee of our company.

Now we will dwell on the general points that are common to every compressor, regardless of its type and model. To get an idea of how to tune a compressor in each case, just call or request a call-back. our representative will answer all your questions.

Why a compressor needs tuning

It is quite obvious that, depending on the tasks performed by the equipment, should change its mode of operation. Maintaining various production processes requires a specific airflow with preset parameters.

An air compressor setting can help keep these parameters within a given range. Besides it is necessary to remember about regular maintenance of unit.

The technical documentation contains the manufacturer’s recommendations, which should be adhered to.

Note. maintenance and tuning of the compressor in the right mode depends on the type of installation. Piston and screw compressor stations have significant design differences. Routine maintenance is, therefore, carried out at various intervals for different types of equipment.

compressor, pressure, regulation, purpose

The general recommendation can be essentially summarized as a periodic check of the operating parameters.

Proper adjustment of the air compressor, timely performance of all routine maintenance activities in full (in particular. control of the integrity and absence of damage to each component and unit of the installation), maintenance of all operating parameters within the norm. all these are essential components of the successful trouble-free and durable operation of the compressor station.

adjusting the switchboard

Having summarized all the basic steps, we can say that compressor adjustment must necessarily include the following operations

  • Checking the integrity and reliability of electrical and air connections, checking the level of lubricating fluids, the integrity and serviceability of the drive, controlling the direction of rotation of the compressor unit;
  • Start-up of the plant, during which the condition and serviceability of the valves are evaluated;
  • Evaluating and checking the unit’s operability without load;
  • Checking the operation of the automatic emergency shutdown systems;
  • Control of temperature conditions in the unit;
  • Troubleshooting and correction of faults;
  • Direct pressure adjustment of the pressure delivered by the compressor.

Please note: this last point should not be entrusted to an untrained worker. Pressure adjustment should only be performed by experienced, trained personnel.

  • The actual maximum and minimum pressures are measured;
  • With the help of the sensor adjustments are changed in the right direction;
  • Shift the operating range (average pressure);
  • After turning on the compressor, repeat the first setting item;
  • If necessary, additional adjustments are made to the maximum, minimum and average values.
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How to adjust the compressor by yourself

If there is no possibility to use services of the qualified expert, it is important to know how to adjust the compressor by yourself. Record the on and off pressure on the pressure gauge when the pump is running. After that, disconnect power and remove the pressure switch cover. There are two screws of different sizes underneath it. The upper screw, the larger one, traditionally adjusts the cutoff pressure.

By rotating it in a certain direction (there should be an arrow marked ” ” and “-” near the screw), depending on whether it needs to raise or lower the shutoff pressure, we achieve the desired result. To check the result of adjustment it is necessary to start the pump and read the manometer again. Comparing it with a previous reading will show how far it has changed during adjustment.

Similarly, the starting pressure is adjusted, using the lower, smaller screw.

For the best performance, the compressor must be correctly set. It is extremely important to follow the manufacturer’s official recommendations. This is quite a complicated procedure, consisting of several successive steps.

First option

All compressors are designed in the same basic operating procedures. Once the required amount of air has been dialed in, the control element of the automation loosens and stops air intake. The air pressure switch works by having air pressed against a diaphragm and counteracting an elastic spring.

For the own adjustment of pressure of the compressor there is a switch in the form of a bolt or nuts, allowing to adjust pressure of the unit. To access it, you need to do the following:

  • remove protection in the form of a shroud;
  • compressor pressure adjustment is made by turning either a bolt or two nuts which increase or decrease spring pressure force;
  • There is a nut next to it to adjust the differential pressure on and off;
  • turn the pressure adjustment bolt to change the indicators, to determine the desired index by testing.

Safety required

Tips in the article “What you need a screw compressor for ” here.

This ability to adjust the pressure is present on all units that use compressed air energy to produce. Plus, the gearboxes of such machines provide pressure control at all stages, so as to ensure the safe operation of all parts of the working structure.

How to configure the compressor for automatic activation?

This feature works on “default” air compressors. Piston compressors have intermittent operation. The motor turns on automatically and actuates the discharge pistons when the air needs to be pumped into the air reservoir. Once the set pressure in the pneumatic system has been reached, the unit turns off.

Controls the mode of the compression relay (pressostat). This device gives the control command to the motor when the pressure in the pneumatic system reaches the set value. When the maximum is reached, the relay triggers to disconnect the motor. the pumping stops. When the compression ratio drops to a predetermined minimum, the pressostat switches on the electric motor to pump air into the system.

The question of setting to automatic activation arises if there are problems with the pressure switch. Usually, it’s not a question of getting the engine to start at all. It is often necessary to set the automatic start at the desired degree of compression of the medium.

How to set the compressor to automatic start?

This feature works on air compressors “by default”. Piston compressors are operated in intermittent mode. The motor turns on automatically and actuates the blower pistons when it needs to pump air into the air reservoir. Once the set pressure in the pneumatic system has been reached, the unit shuts down.

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The compression switch (pressostat) controls the mode. This device gives the control command to the motor when the pressure in the pneumatic system reaches the set value. A relay is set to cut the motor off when the maximum value is reached. the compression stops. When the compression ratio reaches a predetermined minimum, the pressostat turns on the electric motor to pump air into the system.

The question of setting for automatic activation, occurs if there are problems with the pressure switch. Usually it’s not a question of starting the motor at all. It is often necessary to set it to start automatically at the desired compression ratio.

Compressor pressure regulation

As mentioned above, once a certain level of air compression has been achieved in the air reservoir, the pressure switch will turn the compressor motor off. Conversely, when pressure drops to the start limit, the relay will restart the engine.

But often situations arise that force you to change the factory presostat settings and adjust the compressor pressure to your liking. It is possible to change only the lower threshold of switching on because after changing the upper threshold of switching off in the direction of increasing the air will be reset by the safety valve.

To adjust the compressor pressure, proceed as follows.

  • Turn on the machine and record the gauge reading at which the engine turns on and off.
  • Be sure to disconnect the machine from the mains and remove the cover from the pressostat.
  • Having removed the cover, you will see 2 bolts with springs. The large bolt is often marked “P” with a “-” and a “” and is responsible for the upper pressure, upon reaching which the machine will be shut down. To increase the air compression level, turn the regulator toward the ” ” sign, and to decrease it, turn it toward the “-” sign. At first, it is recommended to make half a turn with the screw in the right direction, then turn on the compressor and check the degree of pressure increase or decrease with a pressure gauge. Record at what values the appliance will shut off the motor.
  • With the help of a small screw you can adjust the difference between on and off thresholds. As mentioned above, it is not recommended that this interval exceeds 2 bar. The longer the interval, the less frequent the start-up of the appliance’s motor. In addition, the system will be significant and the pressure drop. Setting the ON/OFF differential is carried out in the same manner as setting the upper ON threshold.

In addition to this, it is necessary to set the reducer, if one is installed in the system. It is necessary to set the level of compression on the gearbox, which corresponds to the working pressure of the pneumatic tool or equipment connected to the system.

In most cases, inexpensive models of air compressors are not equipped with a pressure switch because such products are mounted on a receiver. On this basis, many manufacturers think that a visual pressure monitor by means of a pressure gauge is more than enough. However, if you run the unit for a long time and you do not want to overheat the motor, it makes sense to install a pressure switch for the compressor! With this approach, the actuator will turn off and start automatically.


In terms of maintenance, oil-injected compressors are more complicated than oil-free compressors. At the same time, the devices of the first type are more durable, as well as they can work much longer without interruption. Therefore it is recommended to buy oil devices at home, moreover their cost is much lower. They are suitable, for example, for an airbrush for painting small parts or for other purposes. Oil-free compressors are used in applications where oil-free pneumatic equipment is not allowed to come into contact with oil.

Maintenance of oil-injected equipment

Oil-injected compressors (e.g. Remeza brand) require regular maintenance. Oil level change and control, cleaning and periodic purchase of new filters (air and oil). this is not a complete list of works that must be done for this type of devices to avoid breakdowns and subsequent repairs.

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Maintenance of oil-free equipment

If oil-free equipment is used correctly, it will require much less maintenance than the previous case.

To recap! The only consumable items for oil-free units are air filters.

Daily maintenance

Daily maintenance of compression equipment includes.

  • Visual inspection. Inspect the compressor for dents or other external defects and make sure that the grounding is secure. Next, make sure that the power cord, relief valve, pressure gauge and pressure switch are intact and functioning properly.
  • Check oil level through the inspection window. fluid should be at the level of the red marking. If not, you need to refill. If the oil changes its consistency and color, it must be changed completely. No external fluid should come in contact with the compressor during operation. Always use the same grade of oil that was used before. Do not mix products of different brands, grades or qualities. You need to follow the manufacturer’s recommendations. the manual usually tells you what kind of oil to put in your particular compressor.
  • Inspection of the air ducts. Make sure they are tightly joined together and there are no air leaks. At this time the equipment must be turned off and the pressure in the receiver must not exceed 0.5-0.7 MPa. No air noises should be heard in the connections, if necessary they should be tightened.
  • After work it is necessary to drain the condensate through a special drain installed in the bottom of the receiver. Failure to comply with this rule will lead to leakage of liquid into the pneumoline, and in the receiver will appear rust and corrosion of the metal.
  • In conclusion. the compressor should be cleaned from dirt and dust. This applies to all external surfaces, the piston unit and the electric motor. This procedure is essential for better cooling of the compressor and extending its service life.

All of the above points apply to oil-injected air compressor packages. And for daily maintenance of oil-free devices, you only need to skip point B.

Scheduled maintenance

The routine inspection of a new appliance should be carried out during the running-in phase, i.e. after the first 8 hours of operation following installation and start-up. The service consists in checking the tightening of the bolts on the cylinder heads of the piston unit. This is to compensate for temperature shrinkage.

Next inspection to be made every 50 hours after starting the compressor. The bolts of the cylinder heads are re-inspected. Then the tension of the belts is checked and, if necessary, adjusted. The belts should be cleaned of dirt.

Important! Do not allow belts to be over or under tensioned as this would result in equipment failure.

The oil must be changed after the first 100 hours of operation, and further oilings are carried out every 300 hours. Also check the condition of the intake air filter. If necessary, the part must be cleaned or replaced with a new one. At the same time check the tension of the belts, as well as inspect the electric motor, platform, piston unit and try the strength of their installation.

Important! Every 600 hours the suction air filter must be changed. And every 1200 hours dismantle and clean the check valve from dirt.


The procedure of compressor equipment overhaul includes complete disassembly of the device, replacement of crankshaft bearings, calibration of shaft journals, inspection of nodes and moving joints, parts, as well as other work to restore the factory parameters of the device and ensure its reliable operation until the next scheduled repair.

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