MKS 275420-1-GQ-T-00011, Instruction Manual

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7 Service and Maintenance
48 Series 275 Convectron Module with DeviceNet
Instruction Manual - 275502
The fumes from solvents such as trichloroethylene, perchloroethylene, toluene,
and acetone can be dangerous to health if inhaled. Only use these solvents in
well ventilated areas exhausted to the outdoors. Acetone and toluene are highly
flammable and should not be used near an open flame or energized
electrical equipment.
•
Pins 1 to 2: 19 to 22 ohms
•
Pins 2 to 3: 50 to 60 ohms
•
Pins 1 to 5: 180 to 185 ohms
If the resistance from pins 1 to 2 reads about 800 ohms,
the sensor wire in the gauge is broken. Replace the
gauge tube.
Note: If the resistance values shown here are
correct, but you still think the gauge is not
reading correctly, the gold plating on the
sensor wire may be eroded and the gauge will
have to be replaced.
Figure 7-1 Convectron Gauge Connector and Resistance in Ohms
7.5 Cleaning Contaminated Convectron Gauges
The Convectron Gauge may be baked to 150 ºC nonoperating while under vacuum with the
Module removed.
All materials have been chosen for ultra high vacuum service, corrosion resistance, and bakeability.
The envelope is type 304 stainless steel. All metallic joints in the envelope are welded. No solder is
used within the envelope. The following materials are exposed to the vacuum: Type 304 stainless
steel, Carpenter Alloy 52, Kovar, Kapton, gold-plated Tungsten or Platinum (for the sensor),
borosilicate glass, and Dow-Corning 9015 glass. The blue trim cover is rated at 150 ºC.
When the small sensor wire is contaminated with oil or other films, its emissivity or its diameter may
be appreciably altered and a change of calibration will result. Cleaning with trichloroethylene,
perchloroethylene, toluene, or acetone is possible but it must be done very carefully so as not to
damage the sensor.
Hold the gauge with the main body horizontal and the port projecting upward at an angle of 45
degrees. Slowly fill it with solvent using a standard wash bottle with the spout inserted in the port to the
point where it touches the screen. Let the solvent stand in the gauge for at least ten minutes.
Do not
shake the gauge. Shaking the gauge with liquid inside can damage the sensor wire. To drain the
gauge, position it horizontally with the port facing downward. Slightly warming the gauge will help
dry the gauge. Allow the gauge to dry overnight with the port vertically downward and uncapped.
Before re-installing the gauge on the system, be certain no solvent odor remains.