MIL-STD-1330D(SH)
20 September 1996
5.13.5.4 Procedure.
(a) Transfer 50.0 ± 1.0 mL of the 4.0 percent KHP solution (see
5.13.5.3(a)) to the beaker or erlenmeyer flask.
(b) Add five drops of the 0.2 percent thymolphthalein pH indicator
solution (see 5.13.5.3(b)) to the beaker or erlenmeyer flask. The
KHP solution should be clear.
(c) Fill the syringe or buret with NOC test solution. Record to the
nearest 1 mL the level of the NOC in the syringe or buret.
(d) Slowly add NOC to the KHP solution while swirling the beaker or
erlenmeyer flask until a blue color endpoint persists for 15
seconds. Record to the nearest 1 mL the final level of the NOC in
the syringe or buret.
5.13.5.5 Calculation. Determine the volume of NOC used by subtracting the final level (from 5.13.5.4.(d)) of NOC solution in the syringe or buret from the initial level (from 5.13.5.4.(c)) of NOC solution in the syringe or buret. Record this volume difference in milliliters. Report this number as the alkalinity - mL of NOC. When the alkalinity test measures 35 to 40 mL of NOC, the NOC should be discarded, or recharged as specified in 4.3.1.8.
5.13.6 Detection of hydrocarbon contamination by swipe. This procedure can be used to identify the presence of hydrocarbons in visible contamination. Some non-visible contamination such as a film of hydrocarbon lubricating oil may also be detected. It is intended to supplement the visual inspection methods of
5.13.1.2 to 5.13.1.4 during maintenance or loss of system cleanliness. The procedure does not measure the concentration of hydrocarbon contamination, and shall not be used to certify cleanliness of a system or component not previously cleaned and certified as specified in this standard. The procedure has a sensitivity of only 20 to 30 milligrams per square foot (mg/ft2) hydrocarbons. Systems and components cleaned and certified as specified in this standard have
hydrocarbon cleanliness levels of 3 mg/ft2
5.13.6.1 Equipment.
or less.
(a) Disposable pure teflon membrane filters as specified in B.5.(c) of appendix B. Do not use bonded or laminated teflon filters as these filters contain hydrocarbons that will interfere with the analysis.
(b) A Fourier transform infrared (FTIR) spectrometer.
5.13.6.2 Swipe Procedure.
(a) Using cleanroom gloves as specified in 5.1.6, swipe the area of interest by applying direct pressure to the center of the filter using only one finger and draw for a distance of about 1 to 2 inches. Unlike 5.13.1.4, the swipe area is intended to be very small. In order to detect contamination with the FTIR, it is very important to locate the contamination in the center of the filter in a very small area; preferably less than 10 millimeter diameter.
(b) Transfer the filter to a non-contaminating container such as a clean polyethylene bag as specified in 5.16, or a clean glass or clear hard plastic container. Record the date and the swipe location, and transport to a laboratory for analysis.
5.13.6.3 FTIR Procedure.
(a) Perform about 32 scans of the center swiped area of the filter with the FTIR in absorbance mode with Res 4 and full aperture between
2600 cm-1
and 3400 cm-1.
(b) Review the spectrum for absorbance peaks occurring at the CH stretch region near 2930 cm-1. Absorbance peaks in this region that are 3 to 5 times higher than background are discernable significant peaks that indicate the presence of hydrocarbon contamination requiring corrective action.
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