TB 9-4931-228-24
8. Vacuum
a. Performance Check
NOTE
Operate digital pressure controller in Negative Gage mode for
these vacuum checks, i.e., enter Set points as negative
numbers.
(1) Operate digital pressure controller for TI indications listed in table 3.
The
digital pressure controller will indicate within limits specified.
NOTE
Gently tap TI before each reading to reduce error due to
Table 3. Vacuum Check
Pneumatic pressure standard
indications (inHg)
Test instrument
Marsh, types 2 and 3
indications
Min
Max
5
-4.4
-5.6
10
-9.4
-10.6
15
-14.4
-15.6
20
-19.4
-20.6
1
25
-24.4
-25.6
Location and atmospheric conditions may prohibit calibration
1
at this test point.
(2) Adjust digital pressure controller for zero indication on TI. Set digital pressure
controller to measured pressure.
(3) Deenergize vacuum pump.
(4) Close nitrogen bottle valve, and bleed pressure from all lines. Perform vent
operation on digital pressure controller.
b. Adjustments. No adjustments can be made.
9. Pressure
a. Performance Check
WARNING
To prevent injury to personnel or damage to equipment, make
certain that all components are within range of unit to be
calibrated and all connections are securely sealed prior to
applying pressure to TI. Never attempt to tighten or remove
connections with pressure applied.
