Instruction Manual IGM402 Hornet
InstruTech
Page 36
- ASSIGN RLY A
[Factory default = CG1]
This assigns Relay A to either the CG1 or CG2. The user also has the choice of assigning both relays A & B to
one convection gauge.
- ASSIGN RLY B
[Factory default = CG2]
This assigns Relay B to either the CG1 or CG2. The user also has the choice of assigning both relays A & B to
one convection gauge.
5.8.4.1
SETUP CG1
Two of the most important steps for the initial setup for the convection gauges are to set zero (
SET VAC
) and set
atmosphere (
SET ATM
) as described below. This will ensure proper operation of the gauge and accurate
pressure measurements. The gauge is calibrated at the factory using nitrogen. Furthermore, the gauge is also
installed in a certain orientation when calibrated at the factory. Without setting zero and atmosphere after the
gauge is installed in your system, the gauge may not display the expected and correct pressures. This could be
caused by the fact that you may be using a different gas than Nitrogen such as air to setup and calibrate the
gauge (most commonly the case) and the gauge orientation is different than the orientation used at the factory.
As such, it is very important to perform your own initial setup and calibration by setting zero and atmosphere for
the convection gauges installed in your actual system. Please note the following:
Setting zero
(SET VAC
)
: Setting zero optimizes performance of the gauge when operating at a low pressure
range of 1.00 x 10
-4
Torr to 1.00 x 10
-3
Torr. If your minimum operating pressure is higher than 1.00 x 10
-3
Torr, it
is not normally necessary to set zero and thus setting atmosphere should be adequate. If you are able to
evacuate your system to below 1.00 x 10
-4
Torr, it is always a good practice to check and set zero if necessary.
See “
SET VAC
” below.
Setting Atmosphere (
SET ATM
)
: Setting atmosphere is the most important step for a newly installed gauge. If
you prefer to use air to set atmosphere, vent your vacuum system chamber to expose the gauge to the local
atmospheric pressure (air) and set atmosphere to match your known local uncorrected barometric pressure
(air). This is the reading of ambient air pressure you will expect if you were to vent and open your vacuum
chamber to the atmosphere surrounding the outside of your chamber. At sea level, this pressure is usually near
760 Torr. At elevations above sea level, the pressure decreases. Check your local aviation authority or airport
web sites or your current local weather conditions online to help find your local uncorrected barometric
pressure if you do not have this information.
See “
SET ATM
” below.
Note -
Setting zero and atmosphere is normally required only once during the initial setup and maybe checked
by the user periodically. After power has been applied to the gauge during the initial setup, allow five minutes
for the gauge to stabilize (warm-up) before setting zero and atmosphere.
When operating in units of either mbar or pascals (Pa), you must perform SET ATM before
setting the vacuum reading (SET VACUUM). See SET ATM below. Failure to do so will result in improper
operation of the gauge. If you change units of measure or reset to factory defaults, then this same procedure
must be followed again if the units of measure are being set to either mbar or Pa.
NOTICE
