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5. MAINTENANCE, ADJUSTMENTS AND CALIBRATIONS
Page 105 © 2007 DH Instruments, a Fluke Company
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5.1 OVERVIEW
RPM4 A70M/A20M-AF was designed for maintenance free operation. No maintenance is required other than:
• Regular AutoZeroing of quartz reference pressure transducers (Q-RPTs) (see Section 3.5.1).
• Periodic calibration of Q-RPTs (see Section 5.3).
• Adjustment of the on-board barometer (see Sections 5.2.2).
From a maintenance, calibration and repair point of view, the RPM4 and HPMS are treated as separate
sub-systems.
RPM4/HPMS A70M/A20M-AF is a sophisticated pressure measuring instrument with advanced on-
board features and functions. Before assuming that unexpected behavior is caused by a system defect or
failure, use this manual and other training facilities to become thoroughly familiar with RPM4 operation.
For rapid assistance in specific situations see Chapter 6 for troubleshooting information.
RPM4 is covered by a limited one (1) year warranty. Unauthorized service or repair during the warranty
period is undertaken at the owner’s risk and may cause damage that is not covered under warranty and/or may
void the warranty. For warranty service, contact a DHI Authorized Service Provide (see Table 23).
5.2 RPM4 MAINTENANCE
5.2.1 AUTOZERO OF Q-RPTS
See Section 3.5.1 for complete information on Autozeroing of RPTs.
5.2.1.1 GAUGE MODE AUTOZERO
Since gauge mode AutoZeroing is so easily performed, it is good practice to
AutoZero whenever the RPM4 is vented (open to atmosphere). Before
AutoZeroing, allow at least two minutes for full system stabilization after venting;
be sure that the pressure applied is truly zero (i.e., the RPT is truly
vented/connected to atmosphere with no back pressure) and be sure to consider
the influence of fluid heads.
To cause the range to Autozero, press [AutoZ].