DH Instruments E-DWT-H, Руководство по эксплуатации и обслуживанию

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5. MAINTENANCE, ADJUSTMENTS AND CALIBRATION
Page 99 © 2009 DH Instruments, a Fluke Company
The RPM4-E-DWT also provides complete front panel and remote access to Q-RPT
calibration parameters so that Q-RPT calibrations can be performed without using CalTool
software (see Section 5.3.7).
Note
CalTool for RPTs software supports the calibration process of
RPM4-E-DWT Q-RPTs. CalTool and its documentation are provided on the
General Accessories Disk which is delivered with a new E-DWT-H. CalTool
for RPTs can also be downloaded from www.dhinstruments.com. The use
of CalTool software to assist in the calibration of RPM4-E-DWT is highly
recommended.
5.3.1.1 PA and PM Coefficients
The coefficients used to adjust Q-RPT readings are designated PA (an adder or
offset) and PM (a multiplier or span set). The coefficients affect the Q-RPT
reading following:
Corrected reading = (uncorrected reading • PM) + PA
PA is expressed in units of pressure (always the SI unit, Pascal).
PM is dimensionless.
Since the RPM4-E-DWT operates in gauge mode only and the Q-RPT is zeroed
at the time of calibration and frequently rezeroed during calibration, PA should
not be significantly different from zero.
Each Q-RPT has its own unique PA and PM values. The PA and PM values
currently in use can be viewed and edited from the front panel in the CAL
function (see Section 5.3.6). PA and PM values are automatically edited when
CalTool software results are activated.
Note
•
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 3.9.5.5). Incorrect editing of PA and PM values
can cause out of tolerance measurements.
•
A new RPM4-E-DWT is delivered with PA and PM values
set to zero and 1 for all Q-RPTs. This does not mean that
the RPM4-E-DWT 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.
5.3.2 Equipment Required
Note
The recommended calibration standard for the E-DWT-H RPM4-E-DWT
Q-RPTs is a DHI PG7302 piston gauge. Contact DHI for additional
information.