Granville-Phillips Series 330, Instruction Manual, Page: 40 / 76

5 Convectron Gauge Module
40
Series 330 Vacuum Gauge Controller
Instruction Manual - 330004 - Rev. 02
5.2 Convectron Gauge Tube Installation
5.2.1 Important Precautions for Gauge Tube Installation
Figure 5-2 Convectron Modules - Front and Rear Panels
Convectron gauges should not be used above 999 Torr true pressure. The Series 330
Vacuum Gauge Controller is calibrated for Air/N
2
.
Do not attempt to use a Convectron gauge calibrated for N
2
to measure or control
the pressure of other gases such as argon or CO
2
unless accurate conversion data for
N
2
to the other gas is properly used. If accurate conversion data is not used or
improperly used, a potential overpressure explosion hazard can be created under
certain conditions. For example, at 760 Torr of argon gas pressure, the indicated
pressure on a Convectron gauge calibrated for N
2
is 24 Torr. At an indicated
pressure of 50 Torr, the true pressure of argon is considerably above atmospheric
pressure. Thus if the indicated pressure is not accurately converted to true pressure,
it is possible to overpressure your system.
Overpressure may cause glassware such as ionization gauges to shatter dangerously,
and if high enough may cause metal parts to rupture thus damaging the system and
possibly injuring personnel.
A pressure relief valve should be installed in the system if the possibility of exceeding
999 Torr exist.
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.