When the accumulator charging pressure drops

What happens when an accumulator's pre-charge drops?

Whenever the accumulator pre-charge drops below nominal pressure, the volume of available fluid is reduced, which slows the cycle. The amount of fluid volume an accumulator can deliver to a system depends on the application. If all is well, do a routine check every three to six months after that.

What is a precharge pressure accumulator?

A precharge pressure accumulator is an accumulator with an initial gas pressure called the “precharge pressure.” When the system pressure exceeds this precharge pressure, the nitrogen gas is squeezed, compresses, and decreases in volume, allowing hydraulic fluid into the accumulator.

What happens if the accumulator stays charged?

If the accumulator stays charged, slowly open the drain valve and watch the rate of pressure reduction. When the pressure suddenly drops to zero, this is the pre-charge of the accumulator. For more information about improving the operation of your hydraulic systems, contact your Valmet representative.

What happens when a gas accumulator is pressurized?

When the system is pressurized, the nitrogen compresses as the bottom of the accumulator fills with oil. The nitrogen pressure matches the system pressure, so any reduction in system pressure will cause the accumulator to discharge oil to the system.

What happens when the system pressure exceeds the precharge pressure?

When the system pressure exceeds the precharge pressure, the nitrogen gas is squeezed, compresses and decreases in volume, letting hydraulic fluid into the accumulator. The accumulator’s fluid volume increases until the system reaches its maximum pressure (P2).

Why do gas-charged accumulators lose pressure?

All gas-charged accumulators lose pressure as fluid discharges because the nitrogen gas was compressed by incoming fluid from the pump and the gas must expand to push fluid out. A main disadvantage of this design is that it is not good for high pressure and large volume.