MIL-STD-1330D(SH) APPENDIX B
w/ Change 1
B.7 Samples.
a. A 500 to 600 mL sample of new-unused NOC shall be collected from each container or drum of each lot or batch to establish a baseline NVR.
b. A 500 to 600 mL NOC sample of the NOC effluent from the oxygen system or component being cleaned shall be collected for cleanliness verification.
c. Samples of homogenized NOC used for the gravimetric analysis will be 200 mL. B.8 Preparation and maintenance of apparatus.
B.8.1 Apparatus used in the procedure, including the sample bottles, homogenizer, homogenizing container, graduated cylinder, filtration reservoir, and demineralized water beaker shall have been cleaned as specified in 5.2.
B.8.2 Threaded connections in the filtration reservoir and filter support shall be wrapped with Teflon tape to prevent leakage of the NOC sample.
B.8.3 After contact with NOC, all apparatus shall immediately be rinsed with demineralized water to remove residual NOC to prevent formation of inorganic deposits and to maintain cleanliness.
B.9 Procedure.
B.9.1 Select a membrane filter that has equilibrated to ambient conditions.
B.9.2 Using forceps, weigh the filter to the nearest 0.1 mg, preferably to the nearest 0.05 mg.
B.9.3 Transfer the membrane filter to the filter holder and attach the filter holder to the filtration reservoir as shown on Figure 3. DO NOT OVER TIGHTEN. Over tightening the threaded connections may cause permanent deformation allowing the NOC sample to leak.
B.9.4 Homogenize the 500 to 600 mL NOC sample for 3 minutes at a speed of about 7,500 revolutions per minute (rpm) (position 3 on an OMNI Model GLH homogenizer).
B.9.5 Using an eye-dropper or pipette, wet the filter with about 1 mL of isopropyl alcohol. Allow not less than
15 seconds for the isopropyl alcohol to fully wet the filter. This is observable as a change in filter color from opaque white when dry to translucent when wet.
B.9.6 Optional - Excessive isopropyl alcohol can react with NOC to form a white precipitate that may cause high NVR results. If this interference is suspected, the isopropyl alcohol can be removed from the filter by transferring 15 to 25 mL of demineralized water to the filter reservoir and filtering the demineralized water by vacuum or pressurizing the reservoir with oil-free air or nitrogen before proceeding to step B.9.7.
B.9.7 Transfer 200 mL of homogenized NOC to the filter reservoir.
B.9.8 Filter the homogenized NOC at less than 50 mL/min by vacuum or by pressurizing the reservoir with oil- free air or nitrogen. Very little pressure differential (less than 5 psid) will be required to obtain the desired filtration rate. DO NOT EXCEED A FILTRATION RATE OF 50 MILLILITERS PER MINUTE.
B.9.9 Transfer 100 to 110 mL of demineralized water to the filter reservoir to wash the filter and reservoir of residual NOC.
B.9.10 Filter the demineralized water at less than 50 mL/min by vacuum or by pressurizing the reservoir with oil-free air or nitrogen. Very little pressure differential (less than 5 psid) will be required to obtain the desired filtration rate. DO NOT EXCEED A FILTRATION RATE OF 50 MILLILITERS PER MINUTE.
B.9.11 Remove the filter, place in a petri dish, and dry with petri dish cover ajar in an oven at 131 to 140 °F (55 to 60 °C) for 20 to 30 minutes.
B.9.12 Remove the petri dish with filter from the oven, transfer the filter to an ambient temperature petri dish, and allow it to cool with the cover ajar for at least 2 minutes.
54
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business