3 Installation
24
Series 340 Vacuum Gauge Controller
Instruction Manual - 340005 - Rev. D
3.3 Convectron Gauge Installation
3.3.1 Important Precautions for Gauge Tube Installation
Convectron gauges should not be used above 999 Torr true pressure. The Series 340
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.
Do not operate a Convectron Gauge in an explosive atmosphere.
Do not use the product to measure the pressure of explosive or combustible gases or
gas mixtures. The sensor wire of the Convectron
Gauge normally operates at only
125 ˚C, but it is possible that Controller malfunction can raise the sensor
temperature above the ignition temperature of combustible mixtures.
Do not use the product in the presence of flammable gases or fumes. Cleaning
solvents, such as trichloroethylene, perchloroethylene, toluene and acetone, produce
fumes that are toxic and/or flammable. Use only in areas well ventilated to the
outdoors and away from electronic equipment, open flames, or other potential
ignition sources. Operation of any electrical instrument in such an environment
constitutes a definite safety hazard.
Danger of explosion or inadvertent venting to atmosphere exists on all vacuum
systems which incorporate gas sources or involve processes capable of pressurizing
the system above safe limits.
Do not use a compression mount (quick connect) for attaching the gauge tube to the
system in applications resulting in positive pressures in the gauge tube. Positive
pressures might blow the tube out of a compression fitting and damage equipment
and injure personnel. The Convectron gauge should not be used above 999 Torr
(1333 mbar or 1.33 x 10
+5
pascal).
If the gauge tube will be used to measure pressures greater than 1 Torr or 1 mbar,
the tube must be mounted with its axis horizontal. Although the gauge will read
correctly below 1 Torr when mounted in any position, erroneous readings will result
at pressures above 1 Torr if the tube axis is not horizontal. Erroneous readings can
result in over or under pressure conditions which may damage equipment and injure
personnel.
