MPC1-1000 and MPC1-3000 User’s Manual
5.3.1
TEST INLET VALVE
Two situations can cause a failure to change pressure when using the test inlet valve:
1. A problem with the supply pressure.
2. A plugged filter.
Check the supply and ensure that a gas supply actually exists at the supply port and the
supply pressure is adequate to achieve maximum pressure needs. If the supply is OK, check
the filter by removing the top cover and then removing the filter from the supply line. If the
filter is plugged, disassemble and clean or replace the filter.
5.3.2
VARIABLE VOLUME (VV)
While using the VV to generate pressures it may appear under certain conditions to not be
working when in fact it is. For example, when the system is at low pressure (typically below
20 psia) and working into a large volume. This is due to the compressibility of gases at low
pressures which worsens as pressures decrease and volumes increase. Prevent this
situation when evaluating the performance of the VV.
If pressure cannot be changed through the use of the VV, the problem is with the equalization
valve, the VV piston O-ring or the filter connected to the VV rear plate. Confirm that the
equalization valve is closed (pushed in).
The VV cannot change the pressure when the equalization valve is open. If pressures still
cannot be changed, remove the top panel and the filter. Check the filter for a plugged
condition, clean or replace as needed. If the VV still cannot change the test pressure, have
it serviced.
5.3.3
TEST OUTLET VALVE
Three problems can cause the failure of the test outlet valve to change pressures:
•
An incorrectly positioned outlet selection valve
•
A closed equalization valve
•
A plugged filter
Ensure the outlet selection valve is in the proper position for the work being done (either
VENT or VACUUM). If the valve is in the OFF position, select VENT or VACUUM.
Ensure the equalization valve is open (pull out). If the valve was closed, be aware that a
sudden change of pressure at the test can occur when the valve is opened.
To check if the filter is plugged, select the VACUUM position with the outlet selection valve.
If the system begins to operate correctly the filter is most likely plugged; clean or replace
as needed.
© 2001 - 2007
DH Instruments, a Fluke Company
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