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|  MIL-C-13874K
a . Discharge air pressure less than 175 psig.
b . D i s c h a r g e a i r t e m p e r a t u r e i n e x c e s s o f a m b i e n t + 1 0 0 0F .
c. Free-air capacity less than that specified in table II
4.6.2.3.1 Power consumption. Test unit at rated speed and whole delivering its
r a t e d c a p a c i t y f o r p o w e r c o n s u m p t i o n , u s i n g a calibrated motor or dynamometer.
Horsepower in excess of the continuous horsepower rating of the motor shall
constitute failure of this test.
4 . 6 . 2 . 4 Endurance . O p e r a t e t h e c o m p r e s s o r f o r n o t l e s s t h a n 5 0 0 h o u r s
c o n t i n u a l l y i n p e r i o d s o f n o t l e s s t h a n 4 h o u r s o f r u n n i n g t i m e . O i l changes and
other preventive maintenance shall be performed during downtime. There shall be
no replacement of parts. Adjustments provided by integral devices and repairs
w h i c h require 1 manhour or less may be made. T h e 5 0 0 h o u r s o f o p e r a t i o n s h a l l b e
accomplished at rated capacity and pressure. Record appropriate remarks,
including a record of all stops and adjustments, Record the following data at
least once during each 24 hour period. Readings shall be taken only after at
least 1 hour of continuous operation:
Air temperature, ambient.
a.
Air temperature at receiver discharge.
b.
Air receiver pressure.
c.
Barometric pressure.
d.
Air temperature at compressor intake.
e.
Air temperature upstream of nozzle.
f.
Air pressure at compressor intake.
h Nozzle throat diameter.
i . Nozzle coefficient of discharge.
Differential pressure across the nozzle.
j
k . C o m p r e s s o r unit speed (rpm).
1. C o m p r e s s o r capacity (cfm) computed.
Completion of less than 500 hours of operation at rated capacity and pressure,
d i s c h a r g e a i r t e m p e r a t u r e i n e x c e s s o f a m b i e n t + 1 0 0 0F , r e q u i r e m e n t f o r
replacement of parts, requirement for repairs requiring more than 1 manhour to
complete, or necessity for adjustment not provided for by integral devices shall
c o n s t i t u t e f a i l u r e o f t h i s t e s t . Computed cfm capacity less than specified shall
constitute failure of the test (see 3.15.1 and 3.16.1).
4 . 6 . 2 . 5 H i g h temperature
Unless otherwise specified, subject the compressor
t o an ambient temperature of 120 5 0 F u n t i l a l l c o m p o n e n t s h a v e s t a b i l i z e d a t
this temperature in the test chamber. Then start and operate the compressor at
r a t e d c a p a c i t y a n d p r e s s u r e f o r n o t l e s s t h a n 4 h o u r s w h i l e m a i n t a i n i n g 1 2 0 5 0F
ambient temperature. The operating time for this test may be counted toward the
accomplishment of the endurance test. Record the data as specified in 4.6.2.4 at
30-minute intervals. Failure to start and operate at rated capacity, pressure and
s p e e d , d i s c h a r g e a i r t e m p e r a t u r e i n e x c e s s o f a m b i e n t + 1 0 0 0F o r r e q u i r e m e n t f o r
replacement of parts shall constitute failure of this test.
4 . 6 . 2 . 6 L o w t e m p e r a t u r e . Unless otherwise specified, subject the compressor to
a n a m b i e n t t e m p e r a t u r e o f - 2 5 0F u n t i l a l l c o m p o n e n t s h a v e s t a b i l i z e d a t t h i s
temperature in the test chamber. Then start and operate the compressor at rated
c a p a c i t y , p r e s s u r e a n d s p e e d f o r n o t l e s s t h a n 4 h o u r s w h i l e m a i n t a i n i n g - 2 5 5 0F
ambient temperature. The operating time for this test may be counted toward the
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