MIL-PRF-83756D
which shall be irregular shapes and shall present cleaning problems typical to the application of this type
equipment. While blasting at 80 pounds per square inch gage on a flat surface, the machine shall produce a
cleaned path not less than one inch wide at the rate of one lineal foot in 10 seconds using size 13 glass beads and at
the rate of 4 lineal feet in 10 seconds using 26 grit aluminum oxide. In addition to the cleaning tasks performed,
Almen strips shall be peened to show compliance with Table I as specified.
TABLE I. Performance Characteristics.
Air pressure at
Peen. Intensity
Bead Size
Regulator (psig)
Time (in seconds)
(min), (+.0005 A)
3
40
22
0.0060
3
60
22
0.0100
3
80
22
0.0140
8
40
22
0.0025
8
600
22
0.0040
8
80
22
0.0045
12
40
22
0.0015
12
60
22
0.0020
12
80
22
0.0025
4.4.7 Reclaim system test. The reclaim system test shall be performed using Size 8 glass beads as the blasting
media. The blasting media shall be sieved to insure a sieve analysis conforming to the limits set forth in SAE-
J444. A minimum of 5 pounds of the blasting media shall be cycled through the blast machine at least 10 times
while blasting at 80 pounds per square inch gage against a flat steel plate. The media will then be drained from
the machine and weighed, the weight being recorded. After weighing, the media will again be sieved and the
media retained on the sieve shall weight not less than 80 percent of the weight recorded above. Values less than 80
percent shall cause rejection of the machine.
4.4.8 Exhaust and dust collector test (Type I). During the 4-hour performance test of the Type I blast machine, the
exhaust and dust collector system shall be observed for proper operation. Certification shall be considered as
evidence that the exhaust system replaced the air within the cabinet at least 10 times per minute. However, a dust
free and leak proof system shall still be required and proven to exist.
4.4.9 Recovery and dust collector test (Type II). During the 4-hour performance test of the Type II blast machine,
the recovery and dust collector system shall be observed for proper operation. The contractor shall demonstrate the
recovery system to be 90 percent efficient. The blast gun brushes shall not allow escape of blast media to the
atmosphere. A dust free climate shall exist around the blast machine. The mechanical filter shaker shall be
operated and the dust-tray removed and emptied.
4.4.10 Work floor test (Type I). The work floor shall be loaded at the center with 500 pounds and the maximum
deflection measure. The deflection shall not exceed ¼ inch.
4.4.11 Lighting system test (Type I). Using a General Electric Type 213 light meter or equivalent, the light
intensity shall be checked at the work floor with the access door closed. The light meter shall be placed on the
center of the work floor and moved to each corner in turn. The minimum reading shall be 150 foot candles in each
corner and 200 foot candles at the center.
4.4.12 Individual acceptance test. Each production item blast machine shall be subjected to a one-hour
performance test using blasting media of size 13 glass beads for 30 minutes and 26 grit aluminum oxide for 30
minutes. During the test period, the blast machine shall perform cleaning tasks typical to the application of this
type equipment.
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