Q155 Service Manual
- 4-15 -
4.14.
Operating Pressure Test
Use the following procedure to test the operating pressure of the unit.
i.
Set the unit's ON/OFF switch to the OFF position, and unplug the power cord.
ii.
Remove the cabinet.(See section 4.2.1)
iii.
Connect the pressure gauge to pressure detect fitting on valve set. (Figure
4-25)
iv.
Plug in the power cord, and set the unit's ON/OFF power switch to the ON
position. Set the flow meter to 5 LPM, and allow the unit to run
at least 3
minutes.
v.
Observe the maximum readings on the pressure test gauge.
vi.
The reading should indicate 1~2 bar.
Figure 4-25 Detect operating pressure
4.15.
High Operating Pressure
Higher than normal operating pressure may indicate any of the following:
n
A restrictive blow down muffler, which does not allow the waste (purge) gas to
exit the system freely. Operate the unit with the blow down muffler
disconnected to see if the operating pressure returns to normal.
n
An improperly operating circuit board or solenoid valve. Confirm that the
circuit board and solenoid valves function properly.
n
Contaminated sieve beds. Change the sieve beds.
4.16.
Low Operating Pressure
Lower than normal operating pressure may indicate any of the following:
n
A restriction in the suction resonator, which limits the amount of room air
available to the compressor. Disconnect the suction tube at the compressor,
and allow the unit to operate without the suction resonator to see if normal
operating pressure returns.
n
An improperly operating circuit board or solenoid valve. Confirm that the
circuit board and solenoid valves function properly.
n
A leak in the unit, which allows system pressure to escape. Leak test the unit.
(See section 4.17)
n
A compressor with reduced output. Ensure that the purity level at the desired
liter flow is within Merits
’
specifications. If it is below specifications, replace
pressure detect fitting