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As an important part of air compressor, how does the oil separator tank work?
- Nov 20, 2018 -

The oil separator  tank of the screw air compressor is a pressure vessel which separates the compressed oil-gas mixture. The oil separating core is contained in the pressure vessel. The oil return pipe, the safety valve, the minimum pressure valve and the pressure gauge are installed on the tank body. Now let's look at the structure and working principle of the oil separator tank.


Oil separator tank is generally cylindrical 45 steel welded carbon steel skin tank, there are horizontal and vertical two more commonly used, in the air compressor selection, oil tank made of stainless steel is very rare, under normal circumstances do not use. Another function of the oil separator tank is to store lubricating oil.


The high-pressure and high-temperature oil-gas mixture coming out of the main engine (about 80℃) enters the oil separator along the tangent direction of the oil-gas separator tank. Under the action of centrifugal force, most of the oil in the oil-gas mixture is thrown onto the inner wall of the oil-gas separator tank and flows along the inner wall to the bottom of the oil-gas separator tank under the action of gravity. Another part of the oil droplets condense into large droplets in the process of collision, and finally sink to the bottom of the oil-gas separator tank under the action of gravity to continue to participate in the cycle.


The air filtered by oil separator cores, through the minimum pressure maintenance valve, flows to the rear cooler for cooling, and then discharges the air compressor.


The minimum pressure maintenance valve is also one way valve, which can be called the exhaust valve on the top of the oil tank. Located at the outlet of the oil and gas separator above the oil and gas barrel, the opening pressure is set at about 0.45 MPa. The minimum pressure valve has the following functions:

(1)Check function: when the pressure drop in the oil tank after shutdown, prevent the pipeline compressed air from returning.

(2)When starting, the pressure inside the air compressor should be given priority to ensure the lubrication of the machine.

(3)When the internal pressure of the oil and gas barrel exceeds 0.45 MPa, the air flow velocity through the oil and gas separator can be reduced, the air compressor oil can be prevented from flowing into the gas storage tank in large quantities, and the effect of the oil and gas separator can be ensured, and the damage of the oil and gas separator due to the great pressure difference can also be protected.


There is a safety valve on the end cover of the oil tank. When the air pressure in the oil tank reaches 1.1 times of the set value, the safety valve opens automatically, releases part of the air and reduces the air pressure in the oil tank. The way to check the safety valve is to gently pull the relief ring on the safety valve when the compressor is fully loaded. If the safety valve can exhaust outward, it will be regarded as normal.


A pressure gauge is installed on the oil tank, and the pressure before filtration is checked. The bottom of the oil tank is equipped with a sewage valve. The sewage valve should be opened regularly to release the water and dirt deposited at the bottom of the oil tank.


There is a transparent oil level mirror beside the oil tank showing the oil level in the oil tank. The correct oil level is the middle position between the upper and lower oil levels when the air compressor is working normally. If the oil level is too high, it will run away. If the oil level is too low, the safety of the whole compressor will be affected.


The oil tank is a pressure vessel and must be manufactured by professional manufacturers.