MIL-STD-1622B(SH)
(a)Fill the cleaning equipment with NOC diluted 25 to 50% with grade B
water.
(b)Operate the cleaning equipment covered for 4 hours at 140 to 160oF.
(c)Visually inspect the NOC for foam and precipitate. Visually
inspect the equipment for milky white deposits. Some white
deposits at the fluid-air boundary are acceptable.
(d)If precipitate is visible in the NOC, the NOC foams, or milky white
deposits are visible on the equipment in areas continuously wetted
with NOC, discard the NOC solution, remove the deposits as
specified in 4.2.1.7(e), and repeat the process.
(e)Deposits can be removed by soaking in hot water, or scrubbing
and/or soaking with commercial white vinegar or a warm (up to
110oF) 10 to 16% citric acid solution, followed by a water rinse.
A 10 to 16% citric acid solution can be prepared by adding 12 to
20 ounces of powdered citric acid (CAS No. 77-92-9) to one gallon
of water.
4.2.1.8 Use for extended periods. Extended use of NOC should be in covered equipment to minimize evaporation. Evaporative losses can be made-up with grade B water. NOC can be recycled using filtration, and continuously used or reused, provided the following conditions are satisfied:
(a)For critical applications, a shake test as specified in 5.14.2 reveals no excessive foam.
(b)For critical applications, a clarity inspection as specified in
5.14.3.2 reveals no oil, grease, or excessive particulate.
(c)An alkalinity test as specified in 5.14.5 indicates a satisfactory
result. As the alkalinity of NOC is depleted in use, the volume
of NOC required to obtain the blue end-point specified in 5.14.5
increases. When the alkalinity test measures 35 to 40 milliliters
(mL) of NOC, the NOC is at risk of developing an insoluble
precipitate. The NOC should either be replaced, or a portion of
the low alkalinity NOC removed and replaced with fresh NOC to
restore alkalinity. If evaporation concentrates the NOC causing
the alkalinity test to measure less than 10 mL of NOC, the NOC
should be diluted with water as specified in 4.2.1.6 to restore
the alkalinity to a nominal measured range of 15 to 30 mL of NOC.
Do not attempt to adjust the alkalinity of 50 to 100 percent
concentrated NOC by adding acid; an immediate gel or precipitate
will develop. Alkalinity of NOC in use or stored in cleaning
equipment should be checked weekly until the alkalinity test
measures about 30 mL of NOC. Then, more frequent analysis should
be performed to ensure an insoluble precipitate does not form.
4.2.1.9 Filtration. For long term use in cleaning equipment such as large ultrasonic tanks or parts washers, a filter sized at about 1 micrometer nominal should be installed. For use in a flushing rig, a 5 micrometer nominal or finer filter shall be installed, and it is recommended that a filter sized at about 1 micrometer nominal be installed. A 5 micrometer
filter prevents introducing significant contamination back into the system. A
1 micrometer filter allows recycling and extending the use of NOC. It is also
recommended that for flushing applications, a strainer be installed upstream
of the filter to remove large debris that can prematurely clog the filter.
For critical applications, filters used for the first time shall be checked
for extractable organic material. This is accomplished by recirculating through the filter with clean NOC at 140 to 160oF for no less than 1 hour and then checking for foam as specified in 5.14.2, and performing a visual inspection of the effluent as specified in 5.14.3.2. Checking for extractable
organic material of filters is not required for filters from the same vendor and of the same material that previously tested satisfactorily. A suitable
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