937B Controller Instruction Manual
pg. 33
dangerously, and if high enough may cause metal parts to rupture thus damaging the
system and possibly injuring personnel. Read this Section for proper use of conversion
data.
A pressure relief valve should be installed in the system if the possibility of exceeding
1000 Torr exists. For some gases, be aware the indicated pressure will be higher than the
true pressure. For example, at a true pressure of 9 Torr for helium the indicated pressure
on a Convectron gauge calibrated for N
2
is 760 Torr. The safe way to operate the gauge is
to properly use accurate conversion data.
Refer to Figure 6-9 for setting up a Pirani or Convection Pirani sensor.
Setup Convection Pirani Gauge C2
Gas Type
Auto Zero
Relay
Relay 12
Relay 11
N2
Enable
DIR
SET SP
ABOVE
Hyst
ENABLE
1.0E-02
9.0E-03
BELOW
CLEAR
3.0E-01
3.3E-01
NA
FD
NO
Manual Zero
CP
Message
Box
Auto-detected
Auto-detected
ATM Value 7.6E+02
ATM Cal
NO
Sensor
Figure 6-9 Pirani/Convention Pirani Setup Information Screen
1. Sensor
The Sensor Type (Convection Pirani or Pirani) is often auto-detected during the initial power up. If
the sensor type is auto-detected, the sensor type cannot be changed from the front panel. Should
the auto-detect fail, the sensor type can be selected manually, and stored in the memory. This
information will be used as the default sensor type if sensor power is cycled.
Note that a Sensor ON/OFF sequence should be performed after manually entering the
gauge type.
2. Gas Type
Select the gas type by moving the cursor to the Gas Type box and press the Enter key. Use the
UP or DOWN arrow keys to select the gas type being used with the sensor. Three gas types (N
2
,
Ar and He) can be selected. The default setting is N
2
which is also used for air.
3. FD (Factory Default)
When YES is selected and entered for Factory Default, any Manual Zero and ATM Cal values are
removed and the Zero and ATM values restored to the factory default ones.
A small
U
under the sensor type indicator (PR or CP) on the front panel LCD display will be
removed when default values are restored.