PPCH-G™ OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company
Page 70
In
gauge measurement
mode:
Always leave AutoZ ON when operating.
In
absolute measurement
mode: Always leave AutoZ ON when operating
if
the AutoZ
routine has been run regularly using a valid Z
offset
reference.
In
absolute measurement
mode: Run AutoZ at least every 30 days or when RPM4 has
been exposed to temperature changes exceeding 15 ºC
(36 ºF).
In
absolute measurement
mode: Run AutoZ only when a reference whose measurement
uncertainty is known to be significantly better than that of
the Q-RPT to be AutoZeroed is available. Keep range
ratios in mind when comparing uncertainty.
A ± 0.1 % FS barometer is roughly 100 times better than
a ± 0.01 % 100 MPa (15 000 psi) Q-RPT because the Q-
RPT/barometer pressure range ratio is 1000:1.
In
absolute measurement mode:
Allow the PPCH-G to stabilize at atmospheric pressure
and ambient temperature for 10 to 15 minutes before
running AutoZ. This stabilization period is not necessary
to AutoZ a utility sensor.
In
absolute measurement mode:
Take care to properly consider fluid heads on the
Q-RPTs and the AutoZ reference.
OPERATION
The AutoZ function and values are Q-RPT AND measurement mode (absolute, gauge) specific.
When AutoZ is run for an external Q-RPT in an RPM4, the PPCH-G causes the RPM4 to run
its own AutoZero routine. The RPM4 Q-RPT is then AutoZeroed as if it had been AutoZeroed
independently of the PPCH-G.
To access the PPCH-G AutoZ function menu press
[SPECIAL]
,
<1AutoZ>
. The display is:
1.
Active Q-RPT designator.
2.
Indication of active measurement mode (
<abs>
for absolute,
<gage>
for gauge).
3.
Indication of whether AutoZ is currently ON or OFF for this
Q-RPT and measurement mode.
1off 2view IH
3edit 4run abs ON
Select
<1off>
(or
<1on>
) to change the AutoZ status for the current Q-RPT and
measurement mode from ON to OFF or vice versa.
AutoZ ON is indicated by a <z> in the MAIN RUN screen, top line, fourth character from the
right. When AutoZ is OFF, the character is blank.
Select
<2view>
to view the current value of
P
offset
for the active Q-RPT and measurement mode.
P
offset
should be zero for Axxx Q-RPTs when the PPCH-G is new or has just been calibrated. P
offset
should be roughly equal to atmospheric pressure for a PPCH-G Q-RPT in gauge mode.
