DH Instruments PPCH, Руководство по эксплуатации и обслуживанию

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PPCH™ OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company Page 18
2.3.11 TURN OFF ABSOLUTE MEASUREMENT MODE
PPCH Q-RPTs can operate in both absolute and gauge measurement modes (see Section
3.3.3). If the PPCH will only be used in gauge mode, absolute measurement mode may be
turned off for its Q-RPT(s) so it is no longer accessible. This can avoid confusion and/or
accidental use of the wrong measurement mode. See Section 5.3.5 for complete information
on turning off absolute measurement mode.
2.4 POWER-UP AND VERIFICATION
2.4.1 SWITCH POWER ON
Actuate the power switch on the PPCH rear panel. Observe the front panel display as PPCH
initializes, error checks and goes to the MAIN RUN screen (see Section 3.1.1).
PPCH power-up condition is Internal, Hi Q-RPT or utility sensor active, VENT ON unless the
pressure measured by the Hi Q-RPT is more than 100 kPa (15 psi) away from standard
atmospheric pressure.
If the PPCH fails to reach the MAIN RUN screen, service is required. Record the sequence
of operations and displays observed. Contact a
DHI
Authorized Service Provider (see Table 31).
2.4.2 APPLY PNEUMATIC POWER (DRIVE AIR)
Apply pneumatic power of the appropriate pressure and flow rate to the PPCH
DRIVE
port
(see Section 2.3.5). It is normal for the hydropneumatic pump to cycle a few times when
drive air is applied.
2.4.3 CHECK PRESSURE MEASUREMENT OPERATION
2.4.3.1 CHECKING ABSOLUTE MODE PRESSURE MEASUREMENT
Check that the PPCH operates properly in
absolute
mode.
If the PPCH is not vented (VENT LED ON), press the
[VENT]
direct pressure
control key (see Section 3.1.3).
Use the
[RANGE]
function key to change ranges if necessary and select the
Q-RPT’s DF range (see Section 3.3.1). Press the
[MODE]
function key and
select
<absolute>
(see Section 3.3.3). Use
[UNIT]
to change the pressure unit if
desired (see Section 3.3.2).
Observe the current value of atmospheric pressure. Check that the value agrees
with the local value of atmospheric pressure. Repeat this process for all the Q-
RPTs and or the utility sensor in the PPCH system. Check that the values of
atmospheric pressure measured by the different devices agree with each other
within PPCH or RPM4 measurement tolerances as applicable (see Section
1.2.2.1, 1.2.2.2). Remember to consider that head pressures can be significant
with liquids (see Section 3.3.7). If the Q-RPTs do not agree within tolerances,
the PPCH or RPM4 Q-RPT may need calibration or repair.