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Filter Caddy
FILTER CADDY
Flushing the system is the total cleaning of the hydraulic system, which means actually removing all the oil, components, and cleaning or repairing them as required. Hoses and tubes are cleaned as described in the previous section. It is essential that the reservoir is mechanically cleaned to remove residual contamination particles. The reservoir suction screen and breather must be replaced.
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Hydraulic cylinders must be cleaned and filled with clean oil to eliminate as much air as possible. Elimination of air avoids micro-dieseling. Microdieseling is combustion just like a diesel engine and occurs when hydraulic oil is compressed at high pressure in the presence of air or air bubbles. Micro-dieseling can burn the oil (turns oil blackish) and damage hoses and cylinders internally. Cylinders should not be extended to the end-stops or system relief pressure until the air in the system has been flushed.
Once the hydraulic system has been overhauled and all components cleaned and installed, the hydraulic reservoir needs to be refilled with filtered oil. The filter caddy (Figure 2 or Figure 3) is then used to clean the reservoir oil until a predetermined level of oil cleanliness is achieved. This operation is not possible without a filter caddy. The caddy insures that the reservoir and reservoir oil are clean before the pump is turned.
Next, the pump needs to be bled or the case filled with filtered oil. Only then can the hydraulic system be put into operation. The most critical part of the start-up procedure is when the hydraulic pump is turned for the first time.
Filter caddies are not capable of removing all contaminants from the hydraulic system. As previously explained, hidden particles in the most secluded areas of the hydraulic system make it impossible for any filter caddy to reach into all areas of complex hydraulic systems. However, a filter caddy is an essential tool once the system has been completely disassembled, cleaned and assembled.
Figure 2. Portable Filter Caddy
