instrument panel is obvious from the exploded view,
TABLE 4. PRESSURE GAGE SCALE ERRORS
Figure 5-2. Disassembly should be limited to the removal
of those items believed to be defective or in questionable
condition.
4.5.3
INSPECTION.
Inspect the connecting tube
assemblies and all fittings for worn or damaged threads,
cracks, dents and other defects. Pay particular attention
to the flared ends of the connecting tubes as cracking is
most apt to occur at the root of the flare. Do not attempt
to reclaim a damaged connecting tube assembly by
replacing component parts. Test the pressure gages and
pressure regulators in accordance with the instructions in
paragraphs 4.5.4 through 4.5.6, following.
4.5.4 PRESSURE GAGE TESTS. Each of three pressure
gages should be checked for accuracy at least once every
100 hours of accrued compressor operating time, or
whenever their operation is questionable. The tests shall
be made by subjecting each gage to the pressures
b. Close shut-off valve. Adjust inlet pressure
specified in Table 4, first with the pressure increasing,
regulator to obtain an inlet pressure of 3000 psig. Adjust
then with the pressure decreasing. During the tests, each
handle of low pressure regulator to obtain an outlet
gage should be mounted in the normal operating position
pressure of 50 psig.
(dial face in vertical plane). Two readings should be taken
at each pressure: one before the gage is tapped, the
c. Open shut-off valve to pressurize air bottle.
second after the gage is lightly tapped. The difference of
Regulated outlet pressure shall return to, and stabilize
any two such readings (friction errors) shall not exceed
at, initial set pressure within 10 psi.
plus or minus two per cent of the full scale reading.
d. Repeat tests of steps b and c, preceding, at set
4.5.5 LOW PRESSURE REGULATOR TESTS. Test the
pressures of 100, 150 and 200 psig.
low pressure regulator in accordance with the following
procedure once every six months or whenever its
e. Close shut-off valve. Adjust inlet pressure to
operation is questionable.
3000 psig and outlet pressure to 200 psig.
a. Connect pressure regulator to test set-up as
shown schematically in Figure 4-1.
Figure 4-1. Set-up for Testing Low Pressure Regulator
27
