HYDAC FPO 414 User Manual
3
1-877-GO HYDAC
Charging & Gauging Units
2
Charging & Gauging Units
Operating and
Installation Instruction
Preparation
To check the gas precharge pressure in
an accumulator, it must first be isolated
from the system shut off, and all hydraulic
pressure relieved.
HYDAC gas valve version 11
Unscrew the valve protection cap (where
applicable) and the valve seal cap.
Charging
Warning!
Never use oxygen or air - this could
cause an explosion! Use dry nitrogen or
other recommended gases.
HYDAC recommends the use of a pressure
regulator on the commercially available
nitrogen bottle to regulate pressure to the
charging and gauging unit.
Note: Full nitrogen pressure may damage
the gauge.
Initial Charging
When charging an accumulator that has no
initial gas precharge, allow 20 to 30 minutes
for the gas temperature and thus pressure
to stabilize. Recheck the gas precharge
pressure and adjust if necessary.
General Warning!
Hydraulic accumulators are pressurized
vessels and only qualified technicians
should perform maintenance. For additional
information refer to HYDAC Operating and
Installation Instructions and HYDAC
Maintenance Instructions. Read all instructions
thoroughly before before beginning any type
of service or repair.
Intervals Between Checking
Gas Precharge Pressure
The proper gas precharge pressure should
be set after each new installation or repair
by following the instructions under the
Operating and Installation Instructions
below. It should be rechecked at least once
during the first week of operation. If there is
no loss of gas precharge pressure, it should
be rechecked again in 3 to 4 months.
Thereafter, it should be checked at least
once a year. Recharge accumulator when
necessary.
Temperature Effect
To ensure that the recommended gas
precharge pressure is maintained, even at
relatively low or high operating temperatures,
the gas precharge pressure should be
adjusted for temperature. The formula
below relates the precharge temperature
(T
0
) to the operating temperature (T).
Fahrenheit
P
0,T
0
= P
0,T
2
x (T0+ 460) / (T2+ 460)
Celsius
P
0,T
0
= P
0,T
2
x (T0+ 273) / (T2+ 273)
T
0
= precharge temperature
T
2
= maximum operating temperature
P0,T0= gas precharge pressure at
precharge temperature
P0,T2= gas precharge pressure at
maximum operating temperature
Pressure Increase
When charging an accumulator that has an
existing gas precharge, allow 5 to 10 minutes
for the gas temperature and thus pressure
to stabilize.
Filling
1. Attach the gland & nut portion of the
charging assembly, CGA-677 to a dry
nitrogen bottle, tighten securely.
2. Attach the air chuck to the accumulator
bladder gas valve by hand tightening its
swivel hex connection.
3. Open the gas valve by turning its top
(small) hex nut, counter-clockwise.
4. Set nitrogen bottle gas regulator (if
attached) to 25 psig. (The use of nitro-
gen gas regulator is strongly recommended!)
5. Open nitrogen bottle gas valve. (If you
are not using a nitrogen regulator, care
should be taken to slowly “crack” the
valve open.) With a regulator, valve can
be opened fully.
6. Pre-charge slowly (25 psig) using dry
nitrogen gas, until bladder is fully inflated.
Caution: Initial Precharging Above 25 psig
Will Cause The Bladder to Burst!
7. Continue precharging to desired pressure
by increasing gas flow slowly.
8. Close the valve by turning its top (small)
hex nut, clockwise. Close nitrogen gas
bottle valve.
9. Open bleed valve to release pressure in
the hose and charging head.
10. Remove the charge assembly. Check for
gas leakage. (The use of gas leak detection
fluid or soapy water is recommended.)
11. Replace the valve cap and protective
cap. Tighten, hand tight.
12. Pressurize system. Operate.
Caution:
Precharge Maintenance
For cycling applications check the precharge
weekly. For non-cycling applications, monthly.
You will normally lose some gas over time
due to performance.
A more rapid loss may indicate a gas valve
problem.
1. Release system pressure.
Not gas precharge.
2. Remove gas protective cap (valve guard)
and valve cap.
3. Install gauging device on gas valve stem.
4. For 3000 pis accumulators, screw down
air chuck “T” handle, check pressure.
For 4000 psi or higher, open gas valve
hex fitting (do not loosen from bladder).
Check pressure.
5. Add additional dry nitrogen gas if
necessary, using the above procedures.
6. To release excess nitrogen gas (if any)
open up bleeder valve, located on gauging
head, until desired pressure is achieved.
Pressure Release
With the charging and gauging unit attached
as previously described, gas precharge
pressure can be released by carefully opening manual bleed valve. Release the gas
precharge pressure very slowly until the
desired gas precharge pressure is reached (this
insures that the gas temperature does not fluctuate greatly, providing and accurate gas
precharge pressure). Close the manual
bleed valve. Allow the gas precharge pressure
to stabilize. (5 to 10 minutes) recheck, adjust if
required. Once the desired gas precharge
pressure is reached, refer to steps 8 to 12
under Filling to remove Charging and
Gauging Unit.
Failure to follow proper service and
installation instructions will void
HYDAC product warranty.
• Bladder Accumulators
• Diaphragm Accumulators
• Piston Accumulators
• Nitrogen Bottles
• Dampeners
• Shock Absorbers
• Safety & Shut-off Blocks
• Mounting Components
• Thermal Fuse Caps
• Charging & Gauging Units
• Permanent Gauging Blocks
• Spare Parts, Seal Kits, & Tools
Visit
to download the complete
HYDAC Accumulators Catalog!
Charging and Gauging Unit
FPO 414
Operating Manual
Part No. 02084351
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