Filtration is intended to improve the service life of hydraulic components, but in some cases filters can actually harm the components they’re meant to protect. In order to prevent this, it is critical to choose the correct filter locations and clean or change the filters regularly. Here are some of the most common filter locations along with their possible pros and cons.
Placing filters in the pressure line helps to protect downstream components from damage due to particulate contamination. Due to the high flow velocity and pressure often found here, these filters can be very fine without impeding fluid flow. However, variations in pressure and flow can create issues by disturbing the accumulated particles in the filter. The main downside to this kind of filter is the cost.
The return line is the most common place to find a filter in a hydraulic system. If we start out with clean fluid and a clean tank, the only place contaminants could be picked up is in the other hydraulic components. By filtering fluid before it reenters the tank, we can ensure that any contaminants picked up in this way are captured and do not get recirculated. In this location there is enough pressure for good filtration, but not so much pressure that parts and housing become expensive as in the pressure line location. The main disadvantage of return line filtration is that in some systems, back pressure may be created and result in damage to some components.
Filters located in pump intakes, aka suction filtration, are the type of filter most prone to introducing unintended and harmful side effects. Adding a filter immediately prior to the pump seems like an excellent idea because there is a high fluid velocity followed by a sudden pressure drop here. In other words, there is enough flow to disturb particles and then enough of a rate change to cause the particles to fall out of solution into the filter easily. Unfortunately, if a suction filtration system is allowed to become clogged up, it can create serious problems for your pump. First of all, it can cause cavitation, which will erode the surfaces of your pump components. Secondly, it can create a vacuum effect that will compromise the pistons in the pump.
Ultimately, no matter where you put your filter it will only remain useful so long as it is clean and in good condition. If you need help cleaning or replacing filters or performing any other kind of hydraulic repair or maintenance, feel free to call Bernell Hydraulics.