Functions of Screw Air Compressor Components
1. Function of Air Filter
Its primary function is to prevent impurities such as dust in the air from entering the air compressor system.
Filtration efficiency: 98% of particles of 0.001 mm are filtered out; 99.5% of particles of 0.002 mm are filtered out; 99.9% of particles above 0.003 mm are filtered out.
2. Function of Oil Filter
It removes all wear-causing impurities and dust from lubricating oil without separating the special additives blended into the oil.
Filtration performance of filter paper: 50% of 0.008 mm particles are captured, and 99% of 0.010 mm particles are captured. Counterfeit filter paper fails to pass heated lubricating oil tests. It has fewer pleats, which greatly reduces the filtration area, and the spacing between pleats is uneven.
Function of the Bypass Valve inside the Oil Filter
It prevents oil shortage in the air compressor oil circuit and avoids burnout of compressor components. If the intake air contains high levels of dust, the filter paper will become severely clogged after the lubricating oil has been in service for some time, hindering lubricating oil flow.
When the pressure difference of lubricating oil entering the oil filter reaches a specific value (during cold startup or filter clogging), the built-in bypass valve opens to guarantee sufficient lubricating oil supply in the oil circuit.
The bypass valve must open at the accurate differential pressure. If the set differential pressure is too low, the oil filter loses its filtering effect and causes premature wear of components. If the set differential pressure is too high, insufficient oil supply and excessive lubricating oil temperature will damage the rotors.
Oil Filter Replacement Procedure
Loosen the oil filler plug by one turn to depressurize the system.
Prepare an oil container to avoid oil splashing, then remove the oil filter.
Clean the oil filter base. Apply a thin layer of lubricating oil to the gasket of the new filter, screw the filter onto the base and tighten it manually.
Tighten the oil filler plug.
3. Working Principle of Oil-Air Separator
(1) Core function: Separate compressor lubricating oil from the oil-air mixture and further remove lubricating oil droplets from compressed air.
The oil tank consists of the oil-air separator element, minimum pressure valve, safety valve and tank shell. The oil-air mixture undergoes three separation processes inside the tank: centrifugal separation, gravity separation (oil is heavier than air), and fiber separation.
Separation process: The oil-air mixture enters the oil tank tangentially along the outer wall of the oil-air separator. 80%~90% of oil is separated via centrifugal separation. The remaining 10%~20% oil adheres to the outer surface of the separator for gravity separation. A small amount of oil enters the separator element for fiber separation, and is pressed back into the screw chamber through the oil return pipe.
(2) Conductive gasket of oil-air separator
As air and oil flow through glass fiber, static electricity will be generated between separation layers. If static charge accumulates on two metal layers, electrostatic discharge and electric sparks may occur, which could trigger explosion of the oil-air separator.
The gasket seals the separator element and air receiver, yet static charge may accumulate between the separator element and air receiver housing. Qualified oil-air separator accessories ensure electrical conductivity between the separator element and air receiver shell. Good electrical continuity among all metal components of the air compressor enables timely static dissipation and eliminates electric spark risks.
(3) Adaptability of oil-air separator to differential pressure
The oil-air separator is designed to withstand a maximum differential pressure of 0.5 MPa. If the differential pressure exceeds the limit, the separator element will rupture, resulting in failed oil separation, unit malfunction or complete damage to the separator element.
Every additional 0.1 MPa pressure drop across the separator element increases the overall motor energy consumption by 7%. Excessive pressure drop inside the oil-air separator may cause fire.
Four common causes of excessive differential pressure: separator clogging by contaminants, air backflow, severe internal pressure fluctuation, and counterfeit separator elements.
(4) Electroplated metal components of oil-air separator for corrosion resistance
Condensed water may form inside the oil-air separator depending on ambient conditions (temperature, humidity) and compressor operating conditions. Without electroplating treatment, corrosion layers will form inside the separator. Such corrosion layers destroy antioxidants in compressor lubricating oil, significantly shortening oil service life and lowering the flash point of lubricating oil.
(5) Measures to extend the service life of oil-air separator
Accumulated dust, residual oil, airborne contaminants and abrasion will shorten the service life of the oil-air separator.
① Limit dust ingress into compressor lubricating oil by timely replacing the air filter and oil filter, and observing scheduled oil change intervals.
② Use suitable anti-aging lubricating oil with good water resistance.
Its primary function is to prevent impurities such as dust in the air from entering the air compressor system.
Filtration efficiency: 98% of particles of 0.001 mm are filtered out; 99.5% of particles of 0.002 mm are filtered out; 99.9% of particles above 0.003 mm are filtered out.
2. Function of Oil Filter
It removes all wear-causing impurities and dust from lubricating oil without separating the special additives blended into the oil.
Filtration performance of filter paper: 50% of 0.008 mm particles are captured, and 99% of 0.010 mm particles are captured. Counterfeit filter paper fails to pass heated lubricating oil tests. It has fewer pleats, which greatly reduces the filtration area, and the spacing between pleats is uneven.
Function of the Bypass Valve inside the Oil Filter
It prevents oil shortage in the air compressor oil circuit and avoids burnout of compressor components. If the intake air contains high levels of dust, the filter paper will become severely clogged after the lubricating oil has been in service for some time, hindering lubricating oil flow.
When the pressure difference of lubricating oil entering the oil filter reaches a specific value (during cold startup or filter clogging), the built-in bypass valve opens to guarantee sufficient lubricating oil supply in the oil circuit.
The bypass valve must open at the accurate differential pressure. If the set differential pressure is too low, the oil filter loses its filtering effect and causes premature wear of components. If the set differential pressure is too high, insufficient oil supply and excessive lubricating oil temperature will damage the rotors.
Oil Filter Replacement Procedure
Loosen the oil filler plug by one turn to depressurize the system.
Prepare an oil container to avoid oil splashing, then remove the oil filter.
Clean the oil filter base. Apply a thin layer of lubricating oil to the gasket of the new filter, screw the filter onto the base and tighten it manually.
Tighten the oil filler plug.
3. Working Principle of Oil-Air Separator
(1) Core function: Separate compressor lubricating oil from the oil-air mixture and further remove lubricating oil droplets from compressed air.
The oil tank consists of the oil-air separator element, minimum pressure valve, safety valve and tank shell. The oil-air mixture undergoes three separation processes inside the tank: centrifugal separation, gravity separation (oil is heavier than air), and fiber separation.
Separation process: The oil-air mixture enters the oil tank tangentially along the outer wall of the oil-air separator. 80%~90% of oil is separated via centrifugal separation. The remaining 10%~20% oil adheres to the outer surface of the separator for gravity separation. A small amount of oil enters the separator element for fiber separation, and is pressed back into the screw chamber through the oil return pipe.
(2) Conductive gasket of oil-air separator
As air and oil flow through glass fiber, static electricity will be generated between separation layers. If static charge accumulates on two metal layers, electrostatic discharge and electric sparks may occur, which could trigger explosion of the oil-air separator.
The gasket seals the separator element and air receiver, yet static charge may accumulate between the separator element and air receiver housing. Qualified oil-air separator accessories ensure electrical conductivity between the separator element and air receiver shell. Good electrical continuity among all metal components of the air compressor enables timely static dissipation and eliminates electric spark risks.
(3) Adaptability of oil-air separator to differential pressure
The oil-air separator is designed to withstand a maximum differential pressure of 0.5 MPa. If the differential pressure exceeds the limit, the separator element will rupture, resulting in failed oil separation, unit malfunction or complete damage to the separator element.
Every additional 0.1 MPa pressure drop across the separator element increases the overall motor energy consumption by 7%. Excessive pressure drop inside the oil-air separator may cause fire.
Four common causes of excessive differential pressure: separator clogging by contaminants, air backflow, severe internal pressure fluctuation, and counterfeit separator elements.
(4) Electroplated metal components of oil-air separator for corrosion resistance
Condensed water may form inside the oil-air separator depending on ambient conditions (temperature, humidity) and compressor operating conditions. Without electroplating treatment, corrosion layers will form inside the separator. Such corrosion layers destroy antioxidants in compressor lubricating oil, significantly shortening oil service life and lowering the flash point of lubricating oil.
(5) Measures to extend the service life of oil-air separator
Accumulated dust, residual oil, airborne contaminants and abrasion will shorten the service life of the oil-air separator.
① Limit dust ingress into compressor lubricating oil by timely replacing the air filter and oil filter, and observing scheduled oil change intervals.
② Use suitable anti-aging lubricating oil with good water resistance.
