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Page Title:
Mechanical seal and alignment test |
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|  MIL-P-17639F(SH)
(a) Performance test (see 4.6.6.1).
(b) Mechanical shaft seal and pump alinement procedure test
(see 4.6.6.2).
4.6.6.1 Performance test. The performance tests shall be conducted,
recorded, and reported in accordance with the requirements of the test specified
in 4.6.3, except that, in addition, a full performance map shall be established.
The proposed test procedure for this test shall be submitted to the contracting
activity for approval approximately at the time of drawing submittal. Test data
shall be converted to specified operating conditions for plotting of all perfor-
mance curves. The performance curves shall be determined at maximum and minimum
operating speed for variable speed pumps and at each operating speed for multi-
speed pumps. A full net positive suction head (NPSH) curve is required on lead
production unit and on subsequent units the NTSH shall be determined at design
rated capacity only. The following curves shall be established:
(a)
Capacity
versus
total head.
(b)
Capacity
versus
pump efficiency.
(c)
Capacity
versus
brake horsepower.
(d)
Capacity
versus
net positive suction head required.
Acceptance criteria: The acceptance criteria specified in 4.6.3(a) shall be
met. The performance map shall exhibit the specified pump performance character-
istics. The net positive suction head required shall not exceed the minimum
suction head available specified in 6.2.1. Controls and safety devices shall
function reliably as intended throughout the full operating ranges of capacity
and speed.
4.6.6.2 Mechanical seal and alinement test.
Mechanical seal and alinement
test shall be as follows:
(a) The mechanical seal shall be installed and alined precisely in
accordance with the procedures stated in the proposed pump
technical manual. Packing shall not be installed during this
test. The amount of force required to axially position the
mechanical seal onto the impeller hub, the shaft sleeve or
whatever it rests on in the assembled condition shall be mea-
sured and recorded. If the mechanical seal includes an adhesive
or setting compound on the elastomer that seals between the
mechanical seal and the impeller hub or shaft sleeve, and if
there is a maximum allowed time between initial wetting of
that compound and final positioning of the mechanical seal in
the pump, then do not perform that final positioning until the
maximum allowed time has elapsed.
(b) After installation, the mechanical seal shall be run in and the
pump operated for at least 4 hours at maximum rated speed with
the pumped fluid at maximum operating temperature and with pump
suction pressure as high as feasible without requiring pump test
loop modifications. The seal leak rate shall then be measured
and recorded. Also, the dynamic balance shall be measured and
recorded using a vibration indicator of the neon tube or similar
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