3.4 Threads. - Unless otherwise specified all threads
shall be in accordance with the the National Bureau of Standards
Handbook H28 and supplements thereto. The class or fit for
threads shall be as specified on the applicable drawings, and
the NOT-GO gaging practice shall be as set forth in the
supplement to the aforementioned Handbook H28.
3.5 Performance requirements and product characteristics
The mechanism covered by this specification shall meet the
following performance requirements and product characteris
tics.
3.5.1 Flange Porositv. - The flange shall be capable of
withstanding an air pressure of 60 pounds per square inch
and shokr no leakage when tested as specified in 4.5.3.
3.5.2 Assembly. - The diaphram shall be assembled on the
piston before assembly of the" diaphragm into the flange. The
nut holding the diaphragm on the piston shall be tightened
with a torque of from 25 to 35 pound-inches without distorting
the diaphragm to assure that a watertight seal is made. The
piston-diaphragm sub-assembly shall then be installed in the
flange. The threads of the ring nut shall be coated with
antiseize compound to prevent binding in the flange and special
care shall be used to prevent the antiseize compound from
contacting the diaphragm. The ring nut shall be tightened on
the diaphragm while the piston is In the extended position.
A torque of from 150 to 170 inch-pounds shall be used to
tighten the ring nut without distorting the diaphragm, to
assure that a watertight seal Is made.
3.5.3 Hand operation. - The mechanism shall be assembled
with the safety device in the unlocked condition. The piston
shall be depressed to its fully extended position end then
allowed to return to its normal position There shall be
no binding during the piston travel.
3.5.4 Leakage. - With the safety device in the unlocked
condition. the assembled mechanism shall be capable of with-
standing a pressure differential of 60 pounds per square
inch, without leaking, when tested as specified in 4.5.6.
4
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