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4. General Operation
Operating Conditions
NOTICE: For proper operation, the combination of ambient temperature and process gas temperature
must be such that the gauge temperature remains between -20 and 70°C. The most accurate
measurement of pressure will be obtained if the gauge is zeroed at the operating temperature, as
temperature shifts result in some zero offset.
NOTICE: The HVG-2020A is intended for use in non-condensing environments only. Condensate or any
other liquids which enter the gauge may destroy its electronic components.
Zero Check
Turn the power supply on if not already energized. Typically allow at least 30 minutes for warm-up to be
within rated accuracy. Typically allow at least 2 hours warm-up when adjusting the zero.
Reset the zero using the display menu, the ZERO command, or by pressing the zero-button for 3 seconds. This
zero should be checked periodically during normal operation. Zero adjustment is required if there is a change
in ambient temperature or humidity.
Positive Pressure Operation
WARNING: The HVG-2020A does not have a high-pressure option and is only rated for a
maximum operating pressure of 20 PSIA. Using the instrument above its rated maximum
overpressure of 40 PSIA (25 PSIG), could result in damage to the instrument or alter its
behavior.
WARNING: Do not install a weld stub terminated gauge in an O-ring sealed quick connect fitting
if system pressure could exceed atmospheric pressure.
If pressure goes above 800 Torr, the VAC LED will turn yellow. If the pressure goes above 1000 Torr, it will
begin to flash yellow.
A warning will also appear on the display if the instrument goes over 1000 Torr.
Temperature and Humidity Effects
As the temperature of the instrument changes from the calibration temperature, errors will be introduced into
the output of the instrument. Large changes in humidity will also affect the pressure reading. The shift due to
changes in temperature will affect the zero value and the span value be different amounts as described in the
specification sheet. The effects to the zero reading are eliminated by re-zeroing the instrument at the new
temperature. The span error cannot be eliminated, but is typically less than +0.1 % of reading between 0 and
40 °C and typically less than 0.2% of reading over -20 to 70 °C.
HVG-2020A Instruction Manual
Page 18 of 29
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