
MPC1-1000 and MPC1-3000 User’s Manual
3.4
SETTING NEGATIVE GAUGE PRESSURE (BELOW ATMOSPHERE)
3.4.1
DECREASING PRESSURE
n
Close test outlet valve (4).
o
Rotate outlet selector valve (6) to vacuum position.
For small pressure changes, it may be possible to reach the desired pressure using the VV
only, proceed to Step
p
below.
p
Open pressure equalization valve (3) (pull valve outward).
OPENING THIS VALVE MAY RESULT IN A SUDDEN CHANGE IN THE TEST PRESSURE.
Ensure conditions are such that this either does not happen or that its effects
are inconsequential.
q
Place VV piston (2) at appropriate position, see Section 3.1.3.
r
With a vacuum source connected to the vacuum port, open test outlet valve until the
approximate desired pressure is reached.
s
Close equalization valve (push valve inward).
t
Adjust VV knob until desired pressure is obtained (or until the piston floats when
connected to a piston gauge).
u
To continue decreasing pressures, repeat Step
p
or
t
shown above.
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9
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DH Instruments, a Fluke Company