Air Compressor Oil Separator Burst – Cause Analysis & Case Studies

The oil separator is one of the core components of the air compressor, but a variety of failures could occur in the use, including the oil separator burst fault. Most manufacturers and users would find it very confusing to solve this problem. So in addition to the quality of the oil separator, what are the reasons that will lead to the burst?

This article concludes that there are four main causes for the oil separator burst of the air compressor. At the same time, here are two cases for reference.

Incorrect Sequence of Starting the Compressor

To better play the role of the air compressor, operators will execute all the preparation work before starting the compressor, and then press the start button, until the compressor realizes the normal operation.

However, few operators do not start the machine following the correct steps. For instance, some people directly start the compressor before opening the machine outlet valve, then they run to open the valve, causing the compressed air to flow into the air storage tank.

It’s the wrong sequence that is dangerous to the air compressor safety valve and oil separator core. When the pressure of the compressor increases rapidly, and the gas can not go out, the pressure can become high before the oil separation. If the air outlet is suddenly opened, the pressure inside the oil separator core will be released instantly. As a result, there is a relatively large airflow that impacts the oil separator and increases its load. Sometimes the load will exceed the bearing capacity of the support network, leading the oil separator to burst.

Preventive measures

Professional after-sales workers are required to strengthen the training and demonstration of field equipment operators, to ensure the correct start, use, stop, and daily maintenance.

Oil Separator Blockage & Water Immersion

Oil separator blockage or excessive water would affect the structure of the filtering material, resulting in its deformation and collapse, and an extremely large pressure difference that causes the supporting net to fail.

In the process of separation of oil and gas mixture, the pollutants (dust, particles, dopes, carbon depositions, excess water, and other impurities) also leave on its filtering material. As a result, the filter resistance increases constantly, clogging the oil separator or much water affects the filtering material structure. It leads to the collapse and deformation, and the excessive pressure difference of the oil separator under abnormal conditions.

When the minimum pressure valve is opened, excessive differential pressure resistance acts on the oil separator and exceeds the bearing capacity of the supporting net, thus squeezing the oil separator. Note that the role of the oil separator is to separate oil and gas mixture, rather than to filter and intercept impurities.

Preventive measures

In the case of abnormal working conditions, it is recommended to install pressure sensors or shock absorption pressure gauges before and after the oil separation, so that the pressure can be visually displayed on the panel or the oil barrel. By this, the pressure difference can be calculated.

What’s worse, if working conditions are harsh, it’s necessary to timely report the situation to the sales engineer, so that they can customize the scheme.

Minimum Pressure Valve Failure

The minimum pressure valve is to establish internal pressure and to prevent gas flow back. In case that the minimum pressure valve is stuck or cannot be fully opened, the pressure in the compressor oil separator will be extraordinarily high, and the impact force acting on the oil separator will become larger, which may make it burst.

Preventive measures

Ensure regular inspection, maintenance, and cleaning of the minimum pressure valve under the guidance of the manufacturer.

Damaged Check Valve of the Head

A check valve is set on the outlet pipe on the head of a few compressors. When the check valve is damaged, the oil and gas mixture will impact the oil separator, making it rupture.

Preventive measures

To improve the design or use the check valve with longer service life.

Case Studies

Case 1

The nitrogen compressor is similar to the air compressor in structure, but the compression medium is nitrogen instead of air. And the filter assembly is refitted into the nitrogen filter. A new air compressor has been used for over 400 hours, and the oil separator burst occurred.

It was found that the lubricating oil was dark, and the high-temperature alarm frequency was high, which may be the problem of the lubricating oil. There was a lot of gray dust left on the inner wall of the inlet valve, as well as the inner wall of the nitrogen intake pipe in front of it.

Cause analysis

Lots of particles and dust flowing from the nitrogen intake system entered the main engine directly through the intake pipe. When the oil separator was working, particles were attached to the filter material. Under abnormal conditions, particles accumulation blocked the oil separator, resulting in a large pressure difference that exceeded its bearing capacity.

After cleaning the lubricating oil system and maintaining it to improve the effectiveness of air intake and filtration, the user found that the compressor ran normally.

Case 2

For a 160 kW air compressor, the oil separator has been used for around 3, 500 hours and finally burst. According to the on-site personnel, they cleaned the cooler since the summer was coming. After cleaning and installing, they turned on the machine and found a lot of water in the oil separator.

After the emergency shutdown, they figured out that the seal of the oil cooler failed due to the wrong installation, and the cooling water leaked into the oil circuit system. But the maintenance workers only changed the compressor oil. A few days later, the compressor consumed excessive oil, and then it was shut down. When the machine was taken apart, the oil separator burst.

Cause analysis

The leakage inside the water cooler led to the cooling water in the oil system. During the operation, a large amount of cooling water entered the oil separator, causing the structure of the filter material to collapse, and the large pressure difference made the oil separator explode.

In this case, you’d better replace the oil separator, oil filter, and compressor oil together, because the filter material of the oil core is not water-resistant. The oil filter material encountering cooling water will deform, and the pressure difference becomes larger and the oil runs. Seriously, it could affect the production.


It can be seen from this article that oil separator burst is not common, but the causes are some careless mistakes. Therefore, when using your air compressor, pay attention to correct operation, including starting the machine in the correct sequence, preventing the oil separator from clogging or being soaked in water. Besides, you should check the condition of the minimum pressure valve and the check valve of the head.

Hope these suggestions and case experience can be helpful to you.

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