When groups of filters are to be tested simultaneously, the mounting
distance between filters shall be as specified for the individual groups
otherwise the mounting distance shall be sufficient to minimize the
temperature on one filter affecting the temperature of another. Filters
fabricated of different materials shall not be tested simultaneously. The
test temperature shall be 85 + 2 degrees C. The length of the test shall
be for 5,000 hours. Specified measurements shall be made prior to, during,
or after exposure.
2.6.5.4
Thermal Shock Test
This test is conducted for the purpose of determining the resistance of a
filter to exposures at extremes of high and low temperatures, and to the
shock of alternate exposures to these extremes. Suitable temperature
controlled systems shall be used to meet the temperature requirements and
test conditions. Environmental chambers shall be used to meet test
requirements and to reach specified temperature conditions. Filters shall
be placed so that there is no obstruction to the flow of air across and
around the filter. The filter shall be subjected to the specified test
condition. The first five cycles shall be run continuously. After five
cycles, the test may be interrupted after the completion of any full cycle,
and the filter allowed to return to room ambient temperature before testing
is resumed. One cycle consists of steps 1 through 4 of the applicable test
condition for dual environmental test chambers (one low temperature and one
high temperature test chamber) and steps 1 and 3 for single compartment
test chambers where both high and low temperatures are achieved without
moving the filter. The test conditions are as follows:
1.
-55 deg C. 0 deg and -3 deg
2.
25 deg C. +10 deg and -5 deg
3.
85 deg C. + 3 deg and -0 deg
4.
25 deg C. +10 deg and -5 deg
The effective total transfer time from the specified low temperature to the
specified high temperature shall not exceed 5 minutes. The exposure time
in air at the extreme temperatures is a function of the weight of the
filter. The minimum exposure time per the weight of the filter shall be as
follows:
a.
1 oz. and below 15 minutes
b.
Above 1 oz. to 4.8 oz.
30 minutes
c.
Above 4.8 oz. to 3 lb.
1 hour
d.
Above 3 lb. to 30 lb.
2 hour
e.
Above 30 lb. to 300 lb.
4 hour
f.
Above 300 lb.
8 hour
Specified measurements shall be made prior to the first cycle and upon
completion of the final cycle, except that failures shall be based on
measurements made after the specimen has stabilized at room temperature
following the final cycle.
2.6.5.5
Filters shall be mounted in the filter/ESA assembly enclosure or mounted on
SECTION 13095A
Page 35
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