Instrutech The Hornet IGM402 User Manual page 39

Instruction Manual
Pressing the ENTER key will display the following three settings for CG1:

SET VAC

SET ATM

ANALOG TYPE
- SET VAC
InstruTech advises that you first determine if the 'span' (ATM) adjustment of your measurement device is
set properly before setting the 'zero' (VAC) adjustment. It is good practice to perform the sequence of
checking and adjusting ATM (span) then VAC (zero) and then, finally re-checking the ATM setting to ensure
the instrument has been properly set.
Setting the Zero Point for CG1 (vacuum adjustment):
1. To properly set the vacuum reading ("zero" point), with CG1 installed on your vacuum system, the gauge
should be evacuated to a pressure below 1.00 x 10
2. When the known vacuum system pressure is below 0.1 mTorr, press SET VAC and the number 0.00E+0
Torr will be displayed. If you want to set zero at 0.00E+0 then press the ENTER key repeatedly until the
SET VAC appears on the display again. The zero point (displayed pressure reading with gauge exposed
to vacuum) is now set.
If you want to set the 'zero' pressure reading to a number higher than 0.00E+0, then press the UP or DOWN
keys at each of the high-lighted numeral locations until the desired number is reached; then press the ENTER
key repeatedly until the SET VAC appears on the display again. The new 'zero point' is now set.
Due to the nature of circuit operation and transducer electrical control that cover a full range of
measurement by a convection gauge, it is advised that one first check and adjust, if necessary, the 'span'
and 'zero' to ensure that all measurements made between these two, adjusted settings are as accurate as
possible.
- SET ATM
Setting the Span Point for CG1 (atmosphere adjustment):
1. To set the atmospheric pressure reading (also known as the "span" adjustment), flow nitrogen gas or air
into your closed vacuum chamber to allow the pressure to rise to a known value above 400 Torr.
Alternatively, if your local uncorrected barometric pressure (air) is known, simply vent your vacuum
system chamber to expose the gauge to the local atmospheric pressure.
2. When desired system pressure is stable, press the ENTER key to access the "SET ATM" screen. Adjust
the pressure on the screen to the known value using the UP or DOWN keys. Continue pressing the
ENTER key until the SET ATM appears on the display again. The new atmosphere point is now set. For
example, if your known local uncorrected barometric pressure is 760 Torr, enter 760 in the SET ATM
screen. The CG1 pressure measurement screen will then display 760 Torr while CG1 is at atmosphere.
InstruTech
-4
Torr. [Factory default = 0.00E+0 Torr]
IGM402 Hornet
Page 37