DH Instruments PPC2+, Manual

Page: 137 / 166

PPC2+™ Operation and Maintenance Manual
Page 129
©2001 DH Instruments, Inc.
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Z\O]]_\O`KV_O]aSVVXYVYXQO\LOKMM_\K^OaROX_]ONSXKL]YV_^OWYNO
•
Able to apply pressures at 20 % increments in the range to be calibrated: It is
not necessary that the calibration pressure standard used apply precisely the nominal
pressure value requested for a calibration point as long as the exact value of the
applied pressure is known. Best results will be obtained if the pressure actually
applied is within ±
2 % of FS of the range being calibrated from the
nominal increment. For the zero point on absolute ranges, use the lowest point the
piston gauge can define accurately.
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KNNS^SYXKVSXPY\WK^SYX
2. High accuracy barometer: Needed only if an absolute RPT (AXXXX) is being calibrated
and ZNATERR will be set to allow the use of the autozero function between calibrations
(see Section 3.4.1). Barometer accuracy should be ± 0.01 % or better but its most
important feature is stability over time. Ideally, the same barometer should be used to set
ZNATERR and for subsequent running of the autozero function to update ZOFFSET.
>RO\OMYWWOXNON]Y_\MOPY\WOK]_\SXQK^WY]ZRO\SMZ\O]]_\O^Y]O^D8+>/<<KXNPY\
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-YX^KM^.23PY\KNNS^SYXKVSXPY\WK^SYX
5.2.3 SET-UP AND PREPARATION
To set-up and prepare the PPC2+ for calibration of an RPT:
1. Set the PPC2+ on a stable surface near the calibration standard at an altitude as close as
possible to the calibration standard’s reference height. Consider the connections that may
need to be made to the rear panel and access to the front panel display and keypad.
2. Connect a pressure supply greater than the maximum pressure to be applied during the
calibration to the PPC2+ rear panel SUPPLY port (1/8 in. NPT F). (See Section 2.3.4.)
3. If the calibration will include pressures under atmospheric pressure, connect a vacuum
pump to the PPC2+ rear panel EXHAUST port (1/4 in. NPT F). There will be a constant
bleed of gas through the EXHAUST port so the vacuum pump should be self-venting or
disconnected when OFF (see Section 2.3.5).