Chapter Four: Operation
General
35
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 is:
•
15 minutes for Types 622 and 626 transducers
•
2 to 4 hours for Types 627, 628, and 629 transducers (
≥
1 Torr)
•
8 hours for the 0.05 and 0.1 Torr range units
Lowest Suggested Pressure Available for Reading
The pressures listed in the middle column of Table 11, 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 11, page 36, temperature controlled transducers can obtain repeatable pressure
measurements down to 1 x 10
-5
Torr, and 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 11, 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.