Installation
Mini-Convectron Module with RS-485
19
Instruction Manual - 275545
Saf
e
ty Ins
tructions
Introduction
Installatio
n
O
p
e
ra
tion
M
a
inten
ance
Calibration
2.5
Gauge Tube Construction
The transducer is a convection enhanced Pirani gauge providing rapid
response, six-decades of pressure transduction, stable calibration, and good
accuracy. The Pirani sensing element, R1 of the schematic of Figure 2-1, is
one leg of a Wheatstone Bridge. A temperature compensating network, R2,
forms the second leg of the bridge. The temperature sensitive component of
this network is mounted inside the gauge tube envelope with the sensor. All
other resistors of the bridge are mounted upon the exterior electrical
feedthrough pins of the gauge tube. Pin 4 serves as an electrical terminal for
construction of the compensating network, R2, but no connection is made
therefrom to the controller.
All materials have been chosen for ultra high vacuum service, corrosion
resistance and bakeability to 150 °C. The gauge tube 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 and borosilicate glass.
Figure 2-1
Gauge Tube Schematic
PIN 1
PIN 5
PIN 3
PIN 2
R1
R2
R3
R4
