Downloaded from https://www.everyspec.com . . MIL-STD-2031(SH) 40, PROCEDURE 40.1 Preparation. In accordance with the manufacturer’s operating instructions, the apparatus shall bc prcpard for normal operation. Necessary connections to c[~rnl)rcssed giis supplies shall be made, checking for gas-tight connections, and electrical pot~,cr shall bc connected. Checking for sufficient fume hood draft [o remove smoke and combustion product resulting from the test shall be perfcmned. 40.2 Specimens. The specimens for tes[ing shall be cut to size in advance. The normal size is 1/4 to 1/2 inch wide, 1/8 inch thick, and 6 inches long for self-supporting polymers and composite materials.
Unless some special characteristic of the material that would invalidate the teat results dictates special preparation (for example, a high moisture content), the samples are stored at room atmosphere and tested as received. 40.2.1 Ignition. If the material to be tested can be ignited readily by a 1 inch, normally adjusted Bunsen burner flame, the initial oxygen concentration should be set at 18 percent. If the material is difficult to ignite under these conditions, the initial oxygen concentration should be set at 25 percent. Make the necessary flow valve adjustments to maintain a total flow of 18 literslminute. 40S Cdibmtion of oxygen analyzer. Calibration shall include the following: a.
Position. With the meter range set to the 100 percent scale, select position B1 and the meter should read 90-100 percent. This position has no adjustment. b. Posifion B2. Select position B2; the ,meter should read 90-100 percen~ adjust as ndkk!kild~.’’”” c. Zero position. Select the amplifier zero (AMP ZERO) position, and should read O- 10 percent. Adjust as necessary, N.B. This adjustment is extremely sensitive, proceed with caution. d. Aa’’u.rfrrtenf.If adjustment was required, all settings should be rechecked to ensure that the required conditions have been established. e. PIwsum mguhrtom.
Set the pressure regulatom on the oxygen and nitrogen supply to 25-30 pounds per square inch (lb/in*). f. Nitmgem Gmmence nitrogen flow, adjust for an overall flow rate of 18 litem/minute on the ITA module. Check to see that the oxygen analpw flow rate registers approximately 100 milliliters per minute (mUrn); adjust as appropriate. The oxygen analyzer panel meter should give a steady reading of ZERO percent on both the 25 and 100 percent scales. The DVM should also register ZERO; adjust as appropriate. Cease nitrogen flow. 10