Causes and solutions of oil leakage from oil separation of piston air compressor


Oil leakage is closely related to the following factors: oil quality problems, air compressor system problems, improper oil separation equipment, shortcomings in oil and gas separation system planning, etc. During the actual processing, we found that most of the complaints were not caused by the quality of oil. So, in addition to the quality problem of oil, what other reasons will lead to oil leakage? In practice, we have concluded that the following conditions will also lead to oil leakage:

1. Minimum pressure valve fault

If there is a leakage point at the seal of the minimum pressure valve or the minimum pressure valve is opened in advance (due to the planned opening pressure of each manufacturer, the general range is 3.5 ~ 5.5kg/cm2), the pressure time for establishing the oil and gas tank at the initial stage of operation of the machine will increase. At the moment, the concentration of gas oil mist under low pressure is high, the flow rate through the oil fraction is fast, the oil fraction load increases, and the separation effect decreases, This leads to high fuel consumption.

Solution: repair the minimum pressure valve and replace it if necessary.

2. Unqualified engine oil is used

At present, the general screw air compressors have high temperature protection, and the tripping temperature is generally about 110 ~ 120 ℃. However, some machines use unqualified engine oil, which will show different degrees of oil consumption when the exhaust temperature is high (based on this, the higher the temperature, the greater the oil consumption), The reason is that at high temperature, after the primary separation of the oil and gas barrel, some oil droplets can have the same order of magnitude as the gas phase molecules, and the molecular diameter is ≤ 0.01 μ m. The oil is difficult to capture and separate, resulting in high fuel consumption.

Solution: find out the cause of high temperature, solve the problem, reduce the temperature, and select high-quality engine oil as much as possible.

3. The planning of oil and gas separation tank is not standardized

Some piston air compressor manufacturers, when planning the oil-gas separation tank, the planning of the primary separation system is unreasonable and the primary separation function is not ideal, resulting in high oil mist concentration before oil separation, heavy oil load and lack of treatment ability, resulting in high oil consumption.

Solution: the manufacturer should improve the planning and improve the role of primary separation.

4. Overfuel

When the refueling volume exceeds the normal oil level, part of the oil is taken away with the air flow, resulting in excessive fuel consumption.

Solution: after shutdown, open the oil valve and drain the oil to the normal oil level after the air pressure in the oil and gas barrel is discharged to zero.

5. The return check valve is damaged

If the oil return check valve is damaged (from one-way to two-way), the internal pressure of the oil knockout drum will pour a large amount of oil back into the oil knockout drum through the oil return pipe after shutdown. The oil inside the oil knockout drum will not be sucked back to the machine head in time during the next machine operation, resulting in part of the oil running out of the air compressor with the separated air (this condition is common in machines without oil circuit stop valve and head exhaust outlet check valve).

Solution: check the check valve after removal. If there are sundries, just sort out the sundries. If the check valve is damaged, replace it with a new one.

6. Improper oil return pipe equipment

When replacing, cleaning and repairing the air compressor, the oil return pipe is not inserted into the bottom of the oil separator (Reference: it is better to be 1 ~ 2mm away from the arc center at the bottom of the oil separator), so the separated oil cannot return to the head in time, and the accumulated oil will run out with the compressed air.

Solution: stop the machine and adjust the oil return pipe to a reasonable height after the pressure relief is reset to zero (the oil return pipe is 1 ~ 2mm from the bottom of the oil separator, and the inclined oil return pipe can be inserted into the bottom of the oil separator).

7. Large gas consumption, overload and low pressure use (or the matching between the oil treatment capacity selected before the machine leaves the factory and the exhaust capacity of the machine is too tight)

Load low-pressure use means that when the user uses the piston air compressor, the exhaust pressure does not reach the additional working pressure of the air compressor itself, but it can basically meet the gas consumption requirements of some enterprise users. For example, the enterprise users have increased the gas consumption equipment, so that the exhaust volume of the air compressor can not reach the balance with the user's gas consumption. It is assumed that the additional exhaust pressure of the air compressor is 8kg / cm2, but it is not practical When in use, the pressure is only 5kg / cm2 or even lower. In this way, the air compressor is under load operation for a long time and cannot reach the additional pressure value of the machine, resulting in increased oil consumption. The reason is that under the condition of constant exhaust volume, the flow rate of oil-gas mixture through oil is accelerated, and the oil mist concentration is too high, which aggravates the oil load, resulting in high oil consumption.

Solution: contact the manufacturer and replace an oil separation product that can match the low pressure.

8. The oil return line is blocked

When the oil return pipeline (including the check valve on the oil return pipe and the oil return filter screen) is blocked by foreign matters, the oil condensed at the bottom of the oil separator after separation cannot return to the machine head, and the condensed oil droplets are blown up by the air flow and taken away with the separated air. These foreign matters are generally caused by solid impurities falling from the equipment.

Solution: stop the machine, remove all pipe fittings of the oil return pipe after the pressure of the oil drum is discharged to zero, and blow out the blocked foreign matters. When the oil separator is built in the equipment, pay attention to clean the cover of the oil and gas drum, and pay attention to whether there are solid particles at the bottom of the oil separator core.

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Post time: Nov-16-2021