To maintain system performance HYDAC recommends that the gas precharge pressure is checked regularly. A loss in the gas precharge pressure will cause a drop in the system efficiency and could cause damage to the bladder, diaphragm, or piston accumulator.


HYDAC charging and gauging units allow hydro-pneumatic accumulators to be precharged with dry nitrogen. For these purposes, a charging and gauging unit is connected to a commercially available nitrogen bottle via a flexible charging hose.
These units also allow maintenance personnel to check the current gas precharge pressure of an accumulator. For critical systems, consider the use of a permanent gauging block which will allow constant monitoring.

All HYDAC charging and gauging units incorporate a gauge and check valve in the charging connection, and a manual bleed valve with a T-handle.

HYDAC offers two types of charging and gauging units:

  • FPK - For use with gas valve version 1 (M28 × 1.5) for SBO and SK Series accumulators.
  • FPS - For use with gas valve version 4 (8VI-ISO 4570) for SB, SBO and SK Series accumulators. Note: SB top repairable bladder accumulators must use FPK with FPK/SB adapter.


Available in: Alabama, Arizona, Arkansas, N.W. Florida, S. Idaho, Kansas, Louisiana, Mississippi, W. Missouri, Montana, Nevada, New Mexico, W. North Dakota, Oklahoma, W. South Dakota, Texas, Utah and Wyoming