Gear Pump Manufacturers explain several reasons why […]
Gear Pump Manufacturers explain several reasons why gear pumps mix in air
a. The oil level in the oil tank is too low or the suction pipe is not buried below the oil surface, causing poor oil absorption and inhaling air.
b. The oil filter at the suction pipe of the hydraulic pump is blocked by dirt, or the capacity of the oil filter is not enough, the mesh is too dense, the oil absorption is not smooth, and a partial vacuum is formed to take in air.
c. Drip borrowing throttle oil pipe ‘It’s close to the surface, the oil splash splashes the oil to produce the gas’ bubble, and the bubble is not enough to defoam and is sucked into the pump.
d. The return pipe is above the oil level. When the machine is stopped, the air flows backward from the return pipe (when there is negative pressure in the cylinder).
e. The joints of the oil pipe joints, valves and valve mounting plates of the gear pump system are not tightly sealed, or the air is taken in by the vibration or looseness.
f. Due to seal damage, aging deterioration or poor sealing quality, sealing groove processing, etc., in the position of negative pressure (such as the piston rod at both ends of the hydraulic cylinder, the pump shaft oil seal, the valve adjustment handle and the valve process plug) ), because the seal fails, the air takes advantage of it.
The various reasons why the above air is mixed into the oil are also the cause of the possibility of cavitation. .
The reason why the hydraulic pump generates air pockets. The hydraulic pump suction port is blocked or the capacity is too small, the motor speed of the hydraulic pump is too high, the hydraulic pump installation position (the inlet height) is too high from the oil level, the suction pipe diameter is too small, too much bending, the length of the oil pipe If it is too long, the oil suction filter or the suction pipe is immersed in the oil too shallow, and when the water starts to start, the viscosity of the oil is too large.
The above reasons cause the inlet pressure of the hydraulic pump to be too low. When the air separation pressure is lower than a certain temperature, the dissolved air in the oil is precipitated in the form of air bubbles; when it is lower than the saturated vapor pressure of the liquid, air pockets are formed. phenomenon.
The saturated vapor pressure of the general hydraulic oil (mineral oil) may be 2.254 N/cm2 (o.22X lOsPa), and the air separation pressure is O. IX lOsPa
Throttle gaps (small holes) cause air pockets. According to Bernoulli's equation, the high-speed zone is the low-pressure zone, and the flow velocity of the throttle gap is very high, which is inevitably lower than the pressure in the zone. When the air separation pressure or saturated vapor pressure is lower than the liquid, air pockets are generated.
Similarly, sudden expansion or contraction of the pipe diameter, splitting and confluence of the liquid flow, sudden change of the direction of the liquid flow, etc., may cause a partial pressure loss to cause a pressure drop to become a local low pressure zone, and may also generate cavitation. .
The amount of gas dissolved in the liquid is proportional to the pressure. When the force is reduced, the gas is supersaturated and the air escapes.
The outlet back pressure of the cone poppet valve (such as the cartridge valve, the pilot valve of the force valve and the check valve, etc.) is too low and should be selected according to the regulations.