The oil tank of screw compressor has two functions: oil and gas separation and oil storage. The compressed mixture of oil and gas is discharged to the oil tank, and most of the lubricating oil can be separated by rotating in the oil tank; more lubricating oil is stored to avoid the hot oil just separated from the next cycle immediately, which is conducive to reducing the exhaust temperature.
There are two kinds of oil tank, horizontal type and vertical type, which are commonly used. There are oil cores in the tank. The oil return pipe, safety valve, minimum pressure valve and pressure gauge are installed on the tank body. There is a filling hole on the barrel for refueling.
The air filtered by the oil core is cooled by the rear cooler and then discharged from the air compressor through the minimum pressure maintenance valve.
The minimum pressure maintenance valve is also one way valve, which can be called the exhaust valve on the top of the oil tank. The opening pressure is set to about 0.45 MPa at the outlet of the oil-gas separator above the oil-gas barrel. The minimum pressure valve has the following main functions:
(1) check function: when the pressure drop in the gas tank after shutdown, prevent the pipeline compressed air from returning.
(2) when starting, the cycle pressure of lubricating oil should be set up to ensure the lubrication of the machine.
(3) When the air pressure in the oil and gas barrel exceeds 0.40 MPa, it can reduce the air velocity flowing through the oil and gas separator, ensure the effect of the oil and gas separator, and protect the oil and gas separator from being damaged because of the pressure difference.
There is a safety valve above the end cover of the oil tank. When the air pressure in the oil tank reaches 1.1 times 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 relief valve when the compressor is fully loaded. If the relief valve can exhaust outward, it is considered 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 blowdown valve, which 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 normal oil level is between the upper and lower scales (static oil level for half an hour when the air compressor shuts down), too high will run away, too low will shut down at high temperature.
The oil tank is a pressure vessel and must be manufactured by professional manufacturers.