Watch the gauge showing pressure at the hydraulic side of the accumulator. Start the pump. The gauge will “jump” to the accumulator precharge pressure then slowly climb to full system pressure. Again, watch the gauge. When the pump is powered down, the accumulator precharge will slowly bleed off until the precharge pressure is reached then “drop” to zero.
This is not an accurate check of the precharge, but instead only a quick method to determine the precharge is about where it should be. There are several assumptions here: the gauge is showing accumulator pressure on the hydraulic side, there is a restriction to control the discharge rate at shutdown, and the system is designed to discharge the accumulator at shutdown.
Frank Stilwagner, CFPAI, CFPE, CFPMM, CFPS