VV-L-825C APPENDIX
30.2 Tube opening apparatus. The tube-opening apparatus shown in ASHRAE
97, shall be used.
30.3 Gas handling system. A gas handling system equipped with a vacuum
pump, a sample port to gas chromatograph, and a manometer shall be used. A diagram of this system is shown on figure 1.
30.4 Gas chromatograph. A gas chromatograph equipped with a thermal conduc- ivity detector and a sampling valve shall be used and shall operate as follows:
(a) |
Column temperature: |
75 C |
(b) |
Injector temperature: |
ambient |
(c) |
Detector temperature: |
125 C |
(d) |
Helium flow rate: |
60 milliliters/minute |
(e) |
Sample size: |
5 mL |
(f) |
Recorder span: |
1 millivolt |
(g) |
Chart speed: |
1 inch per minute |
(h) |
Filament current: |
200 milliamperes at 15 volts |
30.5 Column. Ten feet by 1/4 inch Parapak Q, 50-80 mesh, with a 2 inch 50-80 mesh drierite water scrubber at the head of the column.
40. REAGENTS AND MATERIALS
40.1 Helium. Helium shall conform to the requirements of BB-H-1168, type I, grade A.
40.2 Liquid nitrogen. Liquid nitrogen shall conform to the requirements of BB-N-
411, type II.
40.3 TFE tape.
50. PROCEDURE
50.1 A sealed tube shall be stored for 14 days in a 175 C environment. After that period, the tube shall be removed and the lower half shall be submerged in a Dewar flask containing liquid nitrogen until the sample is completely frozen. The tube shall then be removed and a small file scratch shall be made near the tip. The sample shall then be refrozen.
NOTE: After the tube is frozen, the refrigerant pressure is no longer present. However, if noncondensable gases (such as carbon monoxide and hydrogen) were developed by reactions during the aging period, then considerable pressure may still be present in the tube. Also, the tube may have been weakened by the attack of fluorine- containing acids which may have formed during the aging period. If proper care is not used in handling the sample tube, then a serious accident will occur. Therefore, all safety procedures specified in ASHRAE 97 shall be followed.
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