MIL-C-53057(ME)
APPENDIX
TEST METHOD NO. 20
HYDRAULIC SYSTEM ROLL-OFF CLEANLINESS
1. TEST APPATULTUS:
Liquid automatic particle counter.
2. TEST PROCEDURE:
a. Connect the hydraulic lines at the cylinders to bypass those
cylinders whose capacity is less than 1/2 of the connecting
line volume.
b. Run the engine at no-load governed speed pumping the oil
through each circuit for not less than 5 minutes. Perform an
inline particle count: as described in d. below.
c. When applicable, connect each line to its related component.
Operate each function of the system for 5 minutes continuously
through full stroke and at maximum rates. Perform the particle
count as described in d below.
d. The procedure for determining contamination shall be as
follows:
(1) Contamination levels shall be determined by particle
counts. The particle counter used for evaluation of the
samples shall be calibrated in accordance with ANSI
Recommended Standard Method for Calibration of Liquid
Automatic Particle Counters using "AC" Fine Test Dust
(ANSI B93.28). The required counts shall be the average of
not less than three consecutive counts. Samples may be
taken from the reservoir or upstream of the filter(s) used
for cleanup.
(2) Use any combination of on the-crane and off-the-crane
-
filtration for cleanup.
(3) Connect the counter sensor to the system, using a bypass
line and a branch line. The bypass line shall connect to
the system, have a flow rate not less than 5 times the
sensor flow rate, and may return fluid directly to the
reservoir. The branch line to the sensor shall tee into
the bypass line and shall be not more than 12 inches in
length. Any flow restriction devices shall be placed
downstream of the particle counter sensor. Start engine
and operate at not less than 1000 rpm. Record particle
counts.
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