General
Chapter Four: Operation
36
Chapter Four: Operation
General
After installation and during periodic maintenance, check the transducer zero to verify proper
output. If the output is incorrect, set the output by adjusting the zero potentiometer (refer to
Checking the Transducer Zero,
page 25, for zeroing instructions).
The transducer should be powered and allowed to warm up before use. Warm up time is15
minutes.
Lowest Suggested Pressure Available for Reading
The pressures listed in the middle column of Table
Error! Bookmark not defined.
2, page 36,
reflect reliable and practical pressures for different range transducers. Lower readings may be
obtained in environments which have stable temperature and air flow.
As noted in Table
Error! Bookmark not defined.
2, page 36, unheated transducers can obtain
these measurements down to 1 x 10
-4
Torr.
Lowest Suggested Pressure to Use for Control
The pressures listed in the last column of Table
Error! Bookmark not defined.
2, page 36, are
for reference, and represent the pressure reading of the transducer at 50 mV signal output. A DC
signal of at least 50 mV is the recommended minimum signal level to use when integrating any
transducer into complex processing systems.
Suggested Pressures for Reading and Control
Full Scale Range (Torr)
Lowest Suggested Pressure
for Reading (Torr)
Lowest Suggested Pressure
for Control (Torr)
0.1 (Type 626D only)
5 x 10
-5
5 x 10
-4
0.25 (Type 626D only)
1 x 10
-4
1 x 10
-3
1 (Types 622D and 626B)
5 x 10
-4
5 x 10
-3
2 (Types 622D and 626B)
1 x 10
-3
1 x 10
-2
10
5 x 10
-3
5 x 10
-2
20
1 x 10
-3
1 x 10
-1
100
5 x 10
-2
5 x 10
-1
500
2.5 x 10
-1
2.5
1000
5 x 10
-1
5
Table 12: Suggested Pressures for Reading and Control
