Suction Filters
Suction line filters are used to protect the pump in a hydraulic circuit from contaminant that finds its way into the hydraulic oil reservoir. Commonly they are located inside the tank & are screwed onto a hose or boss leading to the inlet port of the pump. Manufactured from a single pleated wire mesh of usually 125 micron size, with thread sizes from ¼” to 3” and flow rates up to 400 l/min. Suction strainers are primarily used to stop larger erroneous particles or items such as nuts & bolts that may accidentally have fallen into the hydraulic power pack reservoir from damaging or destroying the pump.
The issue with fitting this type of filter is that when housed inside the tank it is not possible to monitor its condition as it filters out contaminant. Left unguarded a suction strainer will eventually become so blocked that it starves the pump of fluid, causing cavitation to occur in the inlet line & subsequent damage to and failure of the pump. If the hydraulic reservoir is clean to begin with & the oil in the return line is filtered correctly then suction filters should not be required as the fluid will not contain any particles large enough to be caught by the coarse wire mesh of the strainer. Therefore, it is recommended that if suction strainers are used then they should be monitored regularly with good maintenance procedures in place to avoid this situation.
Alternatively, it is possible to fit an in-line filter in the suction line of the system. Fitted with a removable spin-on element and a wider range of micron rating options it utilises a low pressure by-pass & either visual or electrical indicator to offer more efficient control when protecting the pump.