RPM4/HPMS A70M/A20M-AF Reference Pressure Monitor with High Pressure Mounting System Operation and Maintenance Manual

RPM4/HPMS A70M/A20M-AF OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company Page 108
As editing PA and PM values changes Q-RPT calibration, they should only be
edited by qualified personnel as part of the calibration process. Caution should be
taken to avoid accidental editing and a security system is available to prevent access
(see Section 3.5.5.5). Incorrect editing of PA and PM values can cause out of
tolerance measurements.
A new RPM4 is delivered with PA and PM values set to zero and 1 for all
Q-RPTs. This does not mean that the RPM4 has not been calibrated. In the original
factory calibration, privileged factory coefficients are used for calibration with the
user PA and PM set to zero and 1.
5.3.1.2 AS RECEIVED AND AS LEFT DATA
Frequently, calibration procedures require that as received and as left data be
reported. The necessary information to report as received and as left data on the
calibration of RPM4 Q-RPTs can be obtained in several ways.
When the RPM4 CalTool calibration assistance software is used, as received
data is displayed while running the calibration and is automatically recorded and
reported if desired. As left data is also calculated and presented.
At any time, a) reference pressures applied; b) associated Q-RPT readings;
c) PA, PM and P
offset
(AutoZ offset) values, can be used to calculate as received and as
left values. For example, backing out PA and PM on the as left data yields the Q-
RPT readings with PA = 0 and PM = 1. Then applying the as received PA, PM
and P
offset
values to the readings calculates as received readings (the readings
that the transducer would have made with the old PA, PM and P
offset
).
It is recommended that “as received” values of PA, PM and P
offset
be recorded for
each range prior to running the calibration. The current PA, PM and P
offset
can be
viewed by pressing [SPECIAL], <8cal>, <1view>. P
offset
is only relevant if absolute mode
AutoZero is used in normal operation.
5.3.2 EQUIPMENT REQUIRED
The recommended calibration standard for the RPM4 A70M/A20M-AF Q-RPTs is a DHI
PG7202 piston gauge with a DHI RPM4 A100K reference pressure monitor connected to the
PG7202 as its external barometer. Contact DHI for additional information.
Gas operated piston gauge (deadweight tester), with the following characteristics:
Do not put oil or other liquids into RPM4 A70M/A20M-AF Q-RPTs.
• Measurement uncertainty of ± 0.005 % of reading or better. A standard with higher
measurement uncertainty may be used but RPM4 measurement uncertainty may be
degraded proportionally from normal specifications.
• Able to apply absolute pressures. If, after calibration, the RPM4 will be used in
absolute measurement mode, the calibration must be performed using absolute