MIL-PRF-24790A (SH)
(b)
Halogen concentration excluding fluoride shall not exceed 250 ppm and the packing manufacturer shall
certify in writing that: "the only intentionally added, fluoride-bearing ingredient is
polytetrafluoroethylene," or
(c)
The sum of water-leachable halogens shall be less than 250 ppm when tested as specified in 4.6.4.1.1.
3.4.2 Total sulfur concentration. Packing materials, Type I, Class A, and Type II, Class A, shall be tested for
total sulfur concentration which shall not exceed 700 ppm unless otherwise approved by NAVSEA when tested as
specified in 4.6.4.2.
3.4.3 Mercury. During manufacturing, fabrication, handling and packaging, the pump packing (all types
and classes) shall not come into contact with mercury or mercury compounds.
3.4.4 Other detrimental materials. For packing materials, Type I, Class A, and Type II, Class A, the
maximum concentrations specified in table II also apply (see 4.6.4.3).
TABLE II. Other detrimental materials.
Material
Max concentration (ppm)
Cadmium
250
Lead
250
3.4.5 Asbestos and polychlorinated biphenyls (PCBs). No asbestos or PCBs shall be used in the packing
material (all types and classes) (see 6.3).
3.5 Simulated service testing. Packing materials shall be tested as specified in 4.6.5.
3.5.1 Packing gland leakage rates. Maximum allowable value of the average overall leakage rates during
simulated service testing of rotary and reciprocating pump packings shall be as specified in table III (see 4.6.5 and
6.6).
TABLE III. Maximum allowable value of average overall packing gland leakage rates.
Maximum allowable value
Type/class
No. packing
Shaft speed
Fluid media
of average overall leakage
packing
rings
(fpm.)
rate (max) 1/
Type I, Class A
5
4000
Fresh water
300 mL/min.
4
2100
Fresh water
60 mL/min.
4
1700
Seawater
411 mL/min.
5
5400
Boiler feedwater
945 mL/min.
Type II, Class A
5
170
Sat. L.P. stm.
300 mL/min.
1/ Milliliters per minute (mL/min).
3.5.2 Shaft temperature. During the simulated service testing of Type I, Class A packings (freshwater and
boiler feedwater only), the shaft temperature as measured by the resistance temperature device (RTD) shall meet
the following criteria:
(a)
High speed fresh water (4000 fpm) rotary pump packings.
(1)
The shaft temperature shall not exceed 570 ºF.
(2)
The shaft temperature shall be not greater than 270 ºF for a continuous period of 5 minutes or
more.
(3)
The average overall shaft temperature shall not exceed 260 ºF (see 6.6).
(b)
Low speed fresh water (2100 fpm) rotary pump packings.
(1)
The shaft temperature shall not exceed 570 ºF.
(2)
The shaft temperature shall be not greater than 250 ºF for a continuous period of 15 minutes or
more.
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