Zeroing The Manometer - Omega HHP360 Series User Manual

Zeroing the Manometer

The HHP360 is a stable and precise instrument. However, on
occasion the handheld should have a new zero taken. This is done
to remove zero drift that can occur since it was last zeroed. The
HHP360 can be zeroed only if the new applied zero is within ± 1%
FS of the original factory calibration zero. This prevents accidental
zeroing at atmospheric pressure or other relatively high pressures.
If outside this limit a "ZERO RANGE ERROR" message appears
and the manometer will not zero.
The HHP360 provides three mechanisms for re-zeroing:
1. Referenced to Absolute Zero: This traditional and
preferred method takes a "snapshot" of the measured
pressure when a vacuum of less than 100 microns
Absolute is applied to the sensor.
2. Factory Zero: This method restores the calibration curve
to the original zero taken at the factory. Note that this
feature is intended for comparison purposes, and should
not be used for real pressure measurement, as any zero-
drift will not be compensated.
3. User-Adjusted Zero: This method allows the user to
enter any pressure value when a known reference is
applied (for example, the local barometer). The
manometer will compare its actual measured value with
the entered value, and calculate a new zero reference
based on the offset.
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