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3.
OPERATING PROCEDURE
3.1.
Cautions in Handling
(1)
Start measurement more than one minute after power is turned ON and the indication is
stabilized.
(2) The relay set point sometimes actuated in a moment after three seconds when power is turned
ON.
(3)
For precision measurement, wait for at least 10 minutes until temperature equilibrium of the
sensor head is established after power is turned ON. Do not turn OFF the power when a
sequence of measurements is being made.
(4)
If the sensor head is exposed to a chemically active gas or highly adsorptive gas, its
characteristics may change.
In such a case, fill the chamber with nitrogen or inert gas, with the sensor head energized with
power, and then evacuate it. Repeat this purging operation. The sensor head may be
restored to the condition before the characteristics changed. At this time, do not blow gas
toward the opening plane of the sensor head even if the gas is inert or dry air.
If there is no prospect of the characteristics being restored by purging operation, replace the
sensor head.
(5)
The Pirani vacuum gauge is sensitive to all types of gas, but its sensitivity varies with the
type of gas.
Refer to 7.2 "Types of Measured Gas and Indications".
