Ignitability of DMSO vapors at elevated temperature and reduced pressure

摘要

Ignitability of DMSO vapors have been evaluated at 664 mm Hg pressure. The minimum temperature at which the DMSO vapors that are in equilibrium with liquid DMSO has been determined using two types of strong ignition sources. This temperature is 172 F for chemical igniters, and 178 F for spark ignition. Numerous tests have been conducted using controlled intensity sparks to define the shape of the minimum ignition energy curve as a function of temperature. The ignition energies spanned four orders of magnitude (approximately from 20,000 to 2 mJ) while the DMSO vapor mixture temperature varied from 185 to 207 F. The Sandia Generator was used to simulate worst case electrostatic sparks that can be produced by the human body. Although it was not designed for air discharges, this device had been used by LLNL for 1 mm spark gap and the resultant spark energy had been measured to fall within the range from 3.2 to 8.8 mJ. CRC tests using this device showed that the minimum ignition temperature strongly depends on the spark gap. The minimum ignition temperature was 207 F at 1 mm spark gap, 203 F at 3 mm spark gap, and 197 F at 6 mm spark gap. This strong dependence on the spark gap is believed to be partly due to the changes in the spark energy as the spark gap changes.