The function of filters in hydraulic systems is to maintain fluid cleanliness. Given that the purpose of maintaining fluid cleanliness is to ensure the longest service life of system components, it is necessary to understand that certain filter positions may have negative effects, and the suction pipe is among them.
From the perspective of filtration, the inlet of the pump is the ideal location for filtering media. In theory, there is no high-speed fluid interference with trapped particles, nor is there a high pressure drop that promotes particle separation in the filter element, thereby improving filtration efficiency. However, these advantages may be offset by the flow restriction generated by the filter element in the oil inlet pipeline and the negative impact on pump life.
The inlet filter or suction filter of the pump is usually in the form of a 150 micron (100 mesh) filter, which is screwed onto the pump suction port inside the oil tank. The throttling effect caused by the suction filter increases at low fluid temperatures (high viscosity) and increases with clogging of the filter element, thereby increasing the chance of generating partial vacuum at the pump inlet. Excessive vacuum at the pump inlet may cause cavitation and mechanical damage.
Cavitation
When a local vacuum occurs in the inlet pipeline of the pump, the decrease in absolute pressure can cause the formation of gas and/or bubbles in the fluid. When these bubbles are under high pressure at the pump outlet, they will rupture violently.
Cavitation corrosion can damage the surface of critical components and cause wear particles to contaminate hydraulic oil. Chronic cavitation can cause severe corrosion and lead to pump failure.
Mechanical damage
When a local vacuum occurs at the inlet of the pump, the mechanical force caused by the vacuum itself can lead to catastrophic failure.
Why use them when considering that the suction screens may damage the pump? When you consider that if the fuel tank and the fluid in the tank are initially clean and all air and fluid entering the tank are thoroughly filtered, the fluid in the tank will not contain large enough hard particles to be captured by the coarse suction filter. Obviously, it is necessary to check the parameters of installing the suction filter.
Post time: May-07-2024