Series 111 Accumulators
12
Maintenance
•
Because the precharge pressure level varies with a temperature
change, the level should always be checked at the same temperature.
If it is not, use one of the following formulas to determine if the
precharge level is acceptable.
Degrees Fahrenheit:
Degrees Celsius:
•
If a pressure line accumulator has a pressure level change of ±1.4 MPa
(200 psi) between checks, the accumulator requires maintenance or
the time interval between checks needs to be shortened.
•
If a return line accumulator has a change of ±50% of the original
pressure level between checks, the accumulator requires maintenance
or the time interval between checks needs to be shortened.
•
If the precharge pressure level increases at each check interval, this
indicates that fluid is collecting on the gas side (a small amount of
fluid leakage is normal). When the precharge pressure level cannot be
maintained within the limits, remove the fluid and charge the
accumulator. If the levels are again exceeded at the first check interval,
replace the piston seals after the initial fluid has been changed.
•
If the precharge pressure level decreases at each check interval, this
indicates gas leakage to the fluid side. When the precharge pressure
level cannot be maintained within the limits stated in the previous
guidelines, replace the accumulator piston seals.
•
During normal operation, the accumulator piston should be near the
center of the accumulator cylinder. To check the approximate piston
location, note the warm-to-hot transition point on the accumulator
cylinder wall during operation. If the piston is near the charging stem
end, the accumulator may need charging. If the piston is at the other
end, the accumulator may have an excess charge, or more likely an
excessive amount of hydraulic fluid has collected in the gas chamber.
current pressure
original pressure
460
current temperatrure
(
)
+
460
original temperature
(
)
+
---------------------------------------------------------------------
×
=
current pressure
original pressure
273
current temperatrure
(
)
+
273
original temperature
(
)
+
---------------------------------------------------------------------
×
=
