Causes of Air Compressor Failure

1. Unable to start

There are many possibilities that the compressor cannot be started, but experienced engineers generally follow the steps from simple to complex to consider the problem:

Causes of Air Compressor Failure

1. Unable to start

There are many possibilities that the compressor cannot be started, but experienced engineers generally follow the steps from simple to complex to consider the problem:

1. Electrical failure

First, check whether the power connection of the compressor is correct, whether the power switch is properly closed, whether the power wire is blown, and whether the power voltage reaches 90% or more of the rated voltage. Check whether the pressure of the compressor and the components of the electrical appliances are damaged, and whether the given values ​​of the pressure and electrical appliances are appropriate. The start button is in poor contact. This situation is not very common, because the current screw compressor, unless you really want to buy a machine with a low price, this problem generally does not occur, and even if it occurs, it is very easy to solve.

2. Operation failure

When starting, the outlet switch is not turned on, the pressure setting of the outlet is too high, the switch after the electrical circuit is not restored, and the voltage and current settings are unreasonable, etc.

General screw compressors have automatic protection devices, so when some parts of them fail, they cannot be started normally. Start and stop the control loop, because there are many electrical components and many control points, the failure rate is relatively high. The start button, stop button or switch, etc., due to improper operation, may cause the host to fail to start or malfunction. Such as start button, stop button, emergency stop button, control panel, etc., if the force is too strong during operation, the button may be stuck on the edge of the button housing and cannot be reset.

3. Equipment failure

Mainly include compressor motor failure, rotor lock and so on. If the compressor is overloaded for a long time, it will cause fatigue damage to the rotor tooth surface and the bearing.

If the bearing and the female and male rotors are disassembled when repairing the compressor, if the installation is not careful and the installation accuracy does not meet the requirements, the axis of the female and male rotors will not be parallel and the female and male rotors will not be able to roll. In addition, the method of repairing the compressor was improper, and the method of uncorrected solution was adopted when applying external force to the rotor, which changed the axial and radial gaps between the female and male rotors and made it impossible to rotate.

Under normal circumstances, manufacturers have set parameters such as lubricating oil level, oil pressure and filter pressure difference on the compressor control system. If the above conditions occur, they will automatically stop to protect the compressor. However, for convenience and saving money, some users tend to increase the set parameters or short-circuit certain alarm lines and pipelines, causing the equipment to be separated from the monitoring and lead to failures.

Generally, the probability of motor failure of the compressor is relatively low, but if it occurs, it will be more troublesome, and it needs to be eliminated and repaired by someone.

2. Exhaust pressure is too low

Under normal circumstances, in-service compressors can eliminate the decrease in exhaust pressure caused by higher altitudes, but the increase in gas consumption cannot be ignored. If there is no large leak point in the compressed air line, it is the problem of the compressor unit itself. We can check for problems from the following aspects:

1. Is the maintenance timely?

The compressor discharge volume drops. First of all, check whether the compressor has been maintained. Many times, the compressor displacement is reduced, there is no major problem, it is the customer’s neglect of maintenance. If the working environment is not very ideal, the compressor air filter is easy to be blocked. The light ones can be dedusted with compressed air; if the blockage is serious, a new air filter needs to be replaced.

2. Is the intake valve fully open?

If the compressor discharge volume drops, check the unit. For example, if it has just been maintained, the three filters and oil products will be eliminated. At this time, first check the compressor intake valve. Remove the intake hose, turn on the compressor, and check whether the opening of the intake valve is normal. Generally, the theoretical design life of the intake valve is 100,000 times. Because each manufacturer uses different brands and batches, the quality is also different, so the failure of the intake valve may lead to a decrease in the exhaust volume of the unit.

If the intake valve cannot be fully opened when the compressor is loaded, it can be concluded that the decrease in exhaust volume is the failure of the intake valve, which should be removed for inspection or replacement.

3. Motor failure

After removing the fault of the intake valve, if the exhaust volume of the unit still does not change, it should be considered whether the motor is faulty.

Due to local short-circuit in the motor coil, or bearing wear, motor shaft wear, the motor speed is lower than the rated speed, and the compressor displacement is reduced. The motor coil, bearing, etc. should be repaired, and the compressor displacement should be tested after repair. . Closer to this principle is the belt-driven compressor. The belt load and condition should be considered. Sometimes the speed of the main engine is insufficient due to belt slippage or slack, resulting in low exhaust pressure.

4. The set pressure of the pressure switch is too low

This situation is often caused by changes in the working conditions, or after the system has been adjusted or overhauled, and the system parameters have been changed. Otherwise, under normal circumstances, the working pressure will not be easily misoperated after being set. Compressor parameter setting is not recommended for users to set arbitrarily, but should be combined with equipment suppliers and users to comprehensively consider working conditions and equipment operating characteristics to set a reasonable value.

3. Exhaust oil content is too high

For businesses that are very concerned about air quality, whether the air contains too much oil is critical. There are many reasons for this problem, mainly due to the following reasons: first, the oil level is too high; second, the oil return pipe filter or orifice is blocked; third, the oil and gas separation core is damaged; The fourth is that the gas production pressure of the compressor is too low; then the small pressure valve fails; it is the problem of the lubricating oil itself. If too much foam is used in the lubricating oil, the oil content of the gas will also increase.

1. Too much cooling oil added to the compressor

The added lubricating oil is too much and exceeds the allowable range. During the operation of the compressor, although the separation system separates the oil and gas, in the gas discharge, the gas will also involve the cooling oil into the gas and discharge, resulting in the discharge The oil content in the gas is too high.

2. The oil return line is faulty

In the working process of the screw compressor, the oil return pipeline is responsible for the important responsibility. A pressure difference will form between the oil separator and the compressor inlet. Under the action of this pressure difference, the oil return pipeline is responsible for separating the oil separator. The oil collected at the bottom of the pump is sent back to the compressor for continued use during the next compression cycle.

If the oil return circuit is blocked, broken or installed incorrectly, the oil accumulated at the bottom of the oil separator cannot be transported back to the compressor, resulting in too much oil accumulated at the bottom, then this part of the oil that has not been transported back to the compressor will be lost. As the gas is exhausted, there will be a phenomenon of oil-carrying during the exhaust process.

3. The oil separation core is damaged

During the operation of the screw compressor, if the oil separation core is damaged, such as breakage and perforation, it loses the function of oil and gas separation. That is to say, the mixed gas and the exhaust pipe of the compressor are directly connected, and a large amount of cooling oil is not separated, and is discharged from the body together with the gas, which causes an oil failure during the exhaust process.

4. Failure of small pressure valve

During the operation of the screw compressor, the function of the small pressure valve is to ensure that the system pressure is controlled above the small pressure during the operation. If the small pressure valve fails, the small pressure of the system will not be guaranteed.

Because the air consumption of the luck equipment is very large, the system pressure will be too low, and the oil return line cannot return oil. The oil accumulated at the bottom of the oil separator will not be able to be returned to the compressor, and will be discharged from the compressor with the compressed gas, resulting in oil-carrying failure during the exhaust process.

5. Unqualified cooling oil quality

If lubricating oil with poor defoaming property is added to the compressor, or the ambient air humidity is high, and the bottom of the lubricating oil station leaks water, etc., the lubricating oil will foam, causing the oil content in the exhaust gas to increase.

Fourth, the exhaust temperature is too high

It is not uncommon for screw compressor exhaust temperature to fail too high, so there are many such analysis articles. This article will not describe them one by one, but only summarize from the two aspects of mechanical failure and lubricating oil:

Mechanical failures include

a. Oil stop valve failure;

b. Compressor oil filter failure;

c. The thermal control valve (temperature control valve) fails to work;

d. The compressor oil volume regulator is abnormal;

e. The compressor oil cooler is abnormal (this fault is common in water-cooled compressors);

f. Compressor head failure, including poor lubrication and unreasonable design of the head itself, failure to install and other reasons;

g. Air filter failure;

h. Oil and gas separator failure;

i. The temperature sensor and computer are faulty, and the readings are abnormal.

Compressor oil effects include

a. Insufficient compressor oil;

b. The compressor oil deteriorates, the fluidity of the oil deteriorates, and the heat exchange capacity decreases;

c. Improper selection of compressor oil viscosity;

d. The quality of the compressor oil is not good enough: the thermal oxidation performance is poor, the viscosity-temperature performance is poor, and the air separation ability is poor.

5. The compressor cannot be unloaded Loading and unloading are the basic functions of the compressor. If it cannot be loaded or unloaded, the compressor is useless. Because if it can’t be loaded, the compressor has no compressed air output; if it can’t be unloaded, after there is no compressed air demand downstream, it can be imagined as: “the consequence of constantly inflating a balloon”. During operation, the compressor will continue to load and run when the rated pressure exceeds the rated pressure, which will cause the screw compressor to trip and stop when the set pressure value is reached, or the safety valve will act. If there is no situation that the actual air consumption of the production is greater than the gas production of the compressor unit and a large amount of leakage in the pipeline, then the compressor cannot be unloaded for the following reasons:

a. If the pressure switch is not set properly or appears to float after the setting, false numbers will be reported;

b. The intake valve does not move well, jams, etc.;

c. When the system stops using gas, the relief solenoid valve fails, and the performance state is that the pressure rises slowly, not as soon as it is loaded;

d. The control loop is faulty;

e. The loading solenoid valve is faulty, such as loading at the same time of unloading, and the amount of loaded gas is greater than unloading, so the pressure continues to increase.

 For the failure of the compressor that cannot be unloaded, it is necessary to check whether various valves are jammed or damaged, and repair or replace if necessary.

 At present, screw compressor manufacturers have undergone standardized factory settings before leaving the factory. Most of the problems that occur are caused by untimely maintenance or improper operation. If we strictly abide by the machine operating procedures and pay attention to equipment maintenance, then I believe that many unnecessary equipment failures will not occur.