TABLE 3-14—Variability of autoignition temperature with oxygen concentration at 10.3 MPa (1 494 psi) [43]

Oxygen Concentration (Percent Oxygen)

21 25 50 75 100

Material Temperature (⬚C)

Teflon TFE 438 440 441 437 435

Kel-F 81 367 370 381 382 381

Buna N 380 380 373 343 358

Vespel SP-21 397 409 356 333 338

Noryl 382 374 367 353 325

Silicone 279 278 277 268 278

Tefzel 265 266 254 249 245

Viton A 321 317 295 288 290

Zytel 42 269 267 250 205 194

EPDM 204 203 193 188 187

Polyethylene 195 185 184 180 176

Delrin 183 185 174 172 175

Neoprene 381 375 363 165 164

Buna S 338 157 149 146 146

Fig. 3-11—Pneumatic impact test apparatus.

TABLE 3-15—Pneumatic impact data for nonmetallic materials.

HighestPassingPneumaticImpactPressureLowestFailingPneumaticImpactPressure MaterialaPressure, MPabReactions/TestsSourcecPressure, MPaReactions/TestsSourcec Thermoplastics CTFE Kel-F 813.4 0/20MAPTIS 055216.891/20MAPTIS 05521 3.4 0/20WSTF82-138561/2WSTF82-15670 3.4 0/20WSTF81-138561/20WSTF81-13856 CTFE Neoflon 6.90/20WSTF 02-3730310.319/140WSTF 02-37303 FEP Teflon3.4 0/20WSTF 76-8340, 6.89 1/16WSTF 76-8340, MAPTIS 00649MAPTIS 00649 PTFE, TFE Teflon None3.41/20ASTM STP 1395 p. 521–528, WSTF 98-33222 Fluorogold (glass-fiber 20.70/20WSTF 84-1797724.1 1/8WSTF 84-17977 reinforced PTFE) Fluorogreen E600 20.7 0/20WSTF 84-1797824.1 1/2WSTF 84-17978 (glass fiber reinforced PTFE) TFE w/15 % graphite fill20.7 0/20WSTF 01-3634524.1 1/6WSTF 01-36345 Rulon A (glass-filled PTFE)6.89 0/20MAPTIS 05300None PA Nylon 6/63.450/23MAPTIS 052986.8923/94WSTF 86-20314 6.893/23MAPTIS 05298 PA Zytel 423.4 0/20ASTM STP 13956.9 8/20ASTM STP 1395 p. 521–528 p. 521–528 PC Lexan 0.276 0/20MAPTIS 05197None HDPENone3.4 2/20ASTM STP 1395 p. 521–528 3.451/12WSTF 98-33219 PET Mylar D 3.45d0/20WSTF 01-360346.89d1/3WSTF 01-36034 Vespel SP-1 (unfilled PI)6.89c0/20MAPTIS 051238.6e2/13MAPTIS 05123 Vespel SP21 (15 % graphite-filled PI)20.7 0/20MAPTIS 0512224.1 1/20MAPTIS 05122 POM Delrin3.4 0/20ASTM STP 1395 6.89 14/20WSTF 98-33221 p. 521–5286.9 8/20ASTM STP 1395 p. 521–528 PPO3.4d0/20WSTF 00-358496.89d1/4 WSTF 00-35849 PSO3.45f0/20MAPTIS 052094.1f1/18MAPTIS 05209 Thermosetting Elastomers (Rubbers) CR Neoprene rubber3.45 0/20WSTF 86-205706.89 2/3WSTF 86-20570 FKM Viton A3.4 0/20ASTM STP 1395 6.89 2/20ASTM STP 1395 p. 521–528p. 521–528 FKM Fluorel E21606.89 0/20WSTF 01-3635210.3 1/3WSTF 01-36352 MQ Silicone rubber3.4 0/20ASTM STP 1395 6.89 1/20ASTM STP 1395 p. 521–528p. 521–528

Environments (ASTM G 86). The test is performed by dropping a plummet onto a striker pin, which then transfers the impact energy to the test sample. The maximum impact energy is 98 J (72 ft-lb). The ambient pressure LOX and pressurized LOX or GOX test apparatus are depicted in Figs. 3-12 and 3-13, respec-tively. This test method is predominantly used for nonmetals.

Data

The test data can be used to rank materials for their relative ignitability by mechanical impact, or it can be used to evaluate the use of a material in a specific application where mechani-cal impact could occur. Ambient LOX, pressurized LOX, and pressurized GOX mechanical impact data for nonmetals are presented in Table 3-16. Although mechanical impact tests are not presently used to evaluate metals for oxygen service, data have shown that aluminum, magnesium, titanium, and lithium-based alloys, as well as some lead-containing solders, can be ignited by mechanical impact. A large body of data for mechan-ical impact of metals exists. Some can be found in Ref [55].

Electrical Arc Test Method

Several nonstandardized electrical arc tests methods have been developed. These include a method for determining, with a given voltage, the current needed to produce ignition in

a See Table 3-13 for a description of the material designations used in this column. b G74 standard thickness is 1.52 ⫾0.13 mm (1.39-1.65 mm). All of the data falls within the standard thickness unless otherwise noted. cSources of data are include WSTF, MAPTIS, and ASTM STP 1395 [3-54]. WSTF data are typically referenced by a WSTF number, and MAPTIS data are referenced by a material code. dOnly data found for this material but out of range of standard thickness. Thickness is 1.27 mm. e Only data found for this material but out of range of standard thickness. Thickness is 1.06 mm. f Only data found for this material but out of range of standard thickness. Thickness is 3.35 mm. g Only data found for this material but out of range of standard thickness. Thickness is 1.38 mm.

TABLE 3-15—Pneumatic impact data for nonmetallic materials. (Cont’d)

HighestPassingPneumaticImpactPressureLowestFailingPneumaticImpactPressure MaterialaPressure, MPabReactions/TestsSourcecPressure, MPaReactions/TestsSourcec NBR Buna-N3.45 0/20WSTF 02-37349A6.89 1/2WSTF 02-37349A SBR Buna-SNone3.45g1/20WSTF 98-33215 Greases and lubricants PFPE Krytox 240AC 10.3 0/40WSTF 80-12613, 13.8 3/39WSTF 80-12613, 80-12545 fluorinated lubricant80-12545

Fig. 3-12—Ambient LOX mechanical impact test apparatus.

Fig. 3-13—Pressurized LOX or GOX mechanical impact test apparatus.

TABLE 3-16—Ambient and pr essurized mechanical impact data for nonmetallic materials.

Energy in LOX at Ambient Pressure (14.7 psia)Pressure in LOXPressure in Ambient Temperature (75⬚F) GOX Reactions/ Impact Pressure Reactions/Impact Pressure Reactions/Impact MaterialaTestsEnergy (J)Source(MPa)TestsEnergy (J)Source(MPa)TestsEnergy (J)Source NBR Buna-N3/22b20 MAPTIS 85887None0.10/2098 ASTM STP 1395 pg 87–100 0/20c20 WSTF # 02-36743 1/4c27 WSTF # 02-36743 2/20c27 WSTF # 00-35084 EPDM 0/20c14 WSTF # 00-35085None0.10/2081ASTM STP 1395 pg 87–100 7/20c27 WSTF # 00-35085 FEP (Teflon FEP)0/4098 MAPTIS 006496.890/4098 MAPTIS 006490.6890/2098 MAPTIS 00649 34.53/498 MAPTIS 006493.450/2098 MAPTIS 00649 6.890/2098 MAPTIS 00649 10.30/4098 MAPTIS 00649 40.80/2098 ASTM STP 812 pg 9–42 41.40/2098 MAPTIS 00649 Kel-F 81 (CTFE)0/6098 MAPTIS 055212.780/8098 MAPTIS 055216.80/2098 ASTM STP 812 pg 9–42 0/1098 ASTM STP 812 pg 9–426.892/4198 MAPTIS 055217.240/2098 MAPTIS 05521 0/2098 WSTF # 84-1829613.88/2098 MAPTIS 055217.340/2098 MAPTIS 05521 27.60/2054 MAPTIS 0552110.30/2059 ASTM STP 812 pg 9–42 27.61/961 MAPTIS 0552110.32/2067 ASTM STP 812 pg 9–42 34.533/4098 MAPTIS 0552113.60/2054 ASTM STP 812 pg 9–42 41.44/498 MAPTIS 0552113.81/798MAPTIS 05521 17.21/1898 MAPTIS 05521 20.60/2061 ASTM STP 812 pg 9–42 20.71/798 MAPTIS 05521 22.80/2034 MAPTIS 05521 22.81/641 MAPTIS 05521 24.11/198 MAPTIS 05521 25.40/2047 MAPTIS 05521 25.41/1454 MAPTIS 05521 27.60/2041 MAPTIS 05521 27.61/647 MAPTIS 05521 31.01/198MAPTIS 05521 34.01/674 ASTM STP 812 pg 9–42 34.00/2054 ASTM STP 812 pg 9–42 34.51/198 MAPTIS 05521 37.91/198 MAPTIS 05521 41.43/5634 MAPTIS 05521 41.40/5027 MAPTIS 05521 46.20/10027 MAPTIS 05521 PA Nylon 6/6 2/2041 MAPTIS 052981.7213/2098 MAPTIS 052980.08550/2598 MAPTIS 05298 0/2034 MAPTIS 052983.4520/2098 MAPTIS 052980.70/2098 ASTM STP 812 pg 9–42

TABLE 3-16—Ambient and pr essurized mechanical impact data for nonmetallic materials. (Cont’d)

Energy in LOX at Ambient Pressure (14.7 psia)Pressure in LOXPressure in Ambient Temperature (75⬚F) GOX Reactions/ Impact Pressure Reactions/Impact Pressure Reactions/Impact MaterialaTestsEnergy (J)Source(MPa)TestsEnergy (J)Source(MPa)TestsEnergy (J)Source 6.8920/2098 MAPTIS 052981.720/2088 MAPTIS 05298 10.320/2098 MAPTIS 052981.7214/2098 MAPTIS 05298 3.40/2069 ASTM STP 812 pg 9–42 3.41/2898 ASTM STP 812 pg 9–42 3.450/2081 MAPTIS 05298 3.4510/2088 MAPTIS 05298 6.890/2081 MAPTIS 05298 6.8912/2088 MAPTIS 05298 10.30/2075 MAPTIS 05298 10.314/2081 MAPTIS 05298 20.60/2027 ASTM STP 812 pg 9–42 PEEK 1/3c14WSTF # 02-37348NoneNone Teflon (PTFE 0/26098 MAPTIS 000160.6890/4098 MAPTIS 000160.6890/2098 MAPTIS 00016 Teflon)0/10098 ASTM STP 812 pg 9–420.8620/2098 MAPTIS 000163.450/2098 MAPTIS 00016 0/2098 ASTM STP 1040 pg 11–223.450/2098 MAPTIS 000166.890/2098 MAPTIS 00016 1/20111 ASTM STP 1040 pg 11–224.140/4098 MAPTIS 000167.240/2098 MAPTIS 00016 1/120111 WSTF # 87-215076.890/2098 MAPTIS 0001610.30/4098 MAPTIS 00016 0/12098 WSTF # 87-2150710.30/14098 MAPTIS 0001613.80/2098 MAPTIS 00016 10.30/2098 ASTM STP 812 pg 9–4217.22/698 MAPTIS 00016 17.23/4098 MAPTIS 0001620.73/5698 MAPTIS 00016 20.74/3698 MAPTIS 0001624.11/2498 MAPTIS 00016 34.52/4079 MAPTIS 0001625.30/2098 MAPTIS 00016 34.50/2069 MAPTIS 0001627.63/2998 MAPTIS 00016 37.92/2998 MAPTIS 0001631.03/4698 MAPTIS 00016 41.42/298 MAPTIS 0001634.04/2098 ASTM STP 812 pg 9–42 41.40/2049 MAPTIS 0001634.51/4098 MAPTIS 00016 55.22/398 MAPTIS 0001637.91/298 MAPTIS 00016 58.60/2058 MAPTIS 0001641.41/2047 MAPTIS 00016 58.62/4379 MAPTIS 0001641.40/2034 MAPTIS 00016 58.61/6069 MAPTIS 0001648.32/598 MAPTIS 00016 68.92/4298 MAPTIS 0001655.21/198 MAPTIS 00016 68.90/2049 MAPTIS 0001668.93/2234 MAPTIS 00016 Polyvinyl chloride 2/1120 MAPTIS 60137NoneNone (PVC) Polyurethane None6.8931/175WSTF # 01-36381)6.8930/2025WSTF # 01-36381) rubber6.8931/141WSTF # 01-36381) Rulon A 0/6098 MAPTIS 053000.6890/2098 MAPTIS 053000.6890/2098 MAPTIS 05300 0/10098 ASTM STP 812 pg 9–423.450/2098 MAPTIS 053003.450/2098 MAPTIS 05300 6.890/2098 MAPTIS 053006.890/2098 MAPTIS 05300 10.30/2098 MAPTIS 0530010.30/2027 ASTM STP 812 pg 9–42 10.30/2098 ASTM STP 812 pg 9–4210.31/198 ASTM STP 812 pg 9–42 13.83/8098 MAPTIS 0530013.60/2021 ASTM STP 812 pg 9–42

TABLE 3-16—Ambient and pr essurized mechanical impact data for nonmetallic materials. (Cont’d)

Energy in LOX at Ambient Pressure (14.7 psia)Pressure in LOXPressure in Ambient Temperature (75⬚F) GOX Reactions/ Impact Pressure Reactions/Impact Pressure Reactions/Impact MaterialaTestsEnergy (J)Source(MPa)TestsEnergy (J)Source(MPa)TestsEnergy (J)Source 13.80/2088 MAPTIS 0530013.61/354 ASTM STP 812 pg 9–42 20.70/2027 MAPTIS 0530034.54/498 MAPTIS 05300 20.73/2041 MAPTIS 05300 35.92/3349 MAPTIS 05300 44.15/598 MAPTIS 05300 Silicone 2/20c14WSTF # 00-35089None6.90/2098 ASTM STP 1395 pg 87–100 Vespel SP-1 19/112c98 MAPTIS 051230.6892/1098 MAPTIS 051231.380/2098 MAPTIS 05123 14/40c98 ASTM STP 812 pg 9–421.382/1298 MAPTIS 051233.450/2075 MAPTIS 05123 0/20c47 WSTF # 01-360311.832/698 MAPTIS 051233.451/181 MAPTIS 05123 1/15c54 WSTF # 01-360312.072/4098 MAPTIS 051237.240/2041 MAPTIS 05123 2.766/1798 MAPTIS 051237.241/2747 MAPTIS 05123 3.452/498 MAPTIS 051236.891/198 MAPTIS 05123 7.340/2041 MAPTIS 05123 7.341/347 MAPTIS 05123 10.31/198 MAPTIS 05123 13.81/198 MAPTIS 05123 17.31/198 MAPTIS 05123 37.90/2014 MAPTIS 05123 37.91/1475 MAPTIS 05123 Vespel SP-21 0/22098 MAPTIS 051220.6892/2098 MAPTIS 051220.10/2098 ASTM STP 812 pg 9–42 0/10098 ASTM STP 812 pg 9–421.140/2098 MAPTIS 051220.6890/2098 MAPTIS 05122 0/20111 ASTM STP 1040 pg 11–221.901/16098 MAPTIS 051220.71/1198 ASTM STP 812 pg 9–42 0/120111 WSTF # 88-222422.763/12298 MAPTIS 051220.70/2067 ASTM STP 812 pg 9–42 0/2098WSTF # 77-94303.4515/15298 MAPTIS 051221.720/2098 MAPTIS 05122 0/2098WSTF # 85-188636.894/4281 MAPTIS 051223.4511/8698 MAPTIS 05122 6.890/2047 MAPTIS 051226.80/2081 ASTM STP 812 pg 9–42 7.240/4075 MAPTIS 051226.8919/6298 MAPTIS 05122 7.242/8881 MAPTIS 051226.890/2068 MAPTIS 05122 10.31/3098 MAPTIS 051226.890/18014 MAPTIS 05122 13.81/198 MAPTIS 051227.246/14198 MAPTIS 05122 17.21/598 MAPTIS 051227.240/8088 MAPTIS 05122 20.70/2049 MAPTIS 051227.340/2054 MAPTIS 05122 22.90/2081 MAPTIS 051227.341/1761 MAPTIS 05122 22.91/1588 MAPTIS 0512210.326/7298 MAPTIS 05122 24.11/398 MAPTIS 0512213.83/3698 MAPTIS 05122 27.63/2198 MAPTIS 0512213.80/2034 MAPTIS 05122 31.01/298 MAPTIS 0512217.21/947 MAPTIS 05122 34.56/2498 MAPTIS 0512217.20/1641 MAPTIS 05122 45.62/568 MAPTIS 0512220.71/154 MAPTIS 05122 58.60/2061 MAPTIS 0512224.12/1988 MAPTIS 05122 58.71/2661 MAPTIS 0512227.65/1798 MAPTIS 05122 58.70/2041 MAPTIS 0512231.01/398 MAPTIS 05122 34.03/2021 ASTM STP 812 pg 9–42 34.00/2013 ASTM STP 812 pg 9–42

TABLE 3-16—Ambient and pr essurized mechanical impact data for nonmetallic materials. (Cont’d)

nonmetallic materials. This test is performed in a chamber pressurized as desired with oxygen or a gas mixture, and the apparatus includes a single strand of wire in contact with a test material sample, as shown in Fig. 3-14. Current in the wire is increased until the wire fails, producing an electrical arc.

The data provide a relative ranking of which nonmetallic materials are more susceptible to ignition by electrical arc.

In addition to the electrical arc test method for nonmetal-lic materials, a nonstandardized electrical arc test has been developed to evaluate the ignitability of metals. This method can be used to determine either: (1) the arc energy required to ignite a metallic material at a use pressure where the material is considered flammable; or (2) the threshold pressure at

which a metallic material will ignite with a specified amount of energy. This test is performed in a promoted ignition cham-ber pressurized as desired with oxygen or a gas mixture, and the apparatus includes an electrode positioned against the surface of a metal test sample, as shown in Fig. 3-15. The electrode is rotated away from the sample while electrically powered to draw an electric arc to the sample surface. The data provide a relative ranking of the electrical arc ignitability of metallic materials.

Data

Electrical arc test data for various nonmetallic materials are shown in Table 3-17. The test results indicate that materials Fig. 3-14—Electrical arc test apparatus for nonmetallic materials [56].

Fig. 3-15—Electrical arc test apparatus for metallic materials [57].

that are more finely divided (fuzzy surface) are generally eas-ier to ignite than materials that are in bulk form (smooth sur-face) [56].

Electrical arc test data for carbon steel and aluminum alloys with various surface treatments are shown in Table 3-18 [57].

Static Discharge

A limited number of nonstandardized tests have been per-formed to determine the susceptibility of materials to ignition by static discharge [58]. Tests were performed at a pressure of 0.24 MPa (35 psia) on 100 % cotton, 100 % polyester, facial tis-sue, cotton gauze, petroleum jelly gauze, human hair, and an alcohol prep pad. With the exception of the alcohol prep pad, none of the materials ignited in 100 % oxygen with thirty 15 000-volt sparks in the range of 15 to 20 mJ (which is the upper limit of discharges from a human). The alcohol prep pad was ignited with one 15 000-V, 15 to 20 mJ spark in air.

Resonance

A limited number of nonstandardized tests have been per-formed to determine the susceptibility of materials to ignition by resonance [59]. The resonance test apparatus consisted of an inlet tube, an exit tube, and a resonance tube, forming a tee.

The temperatures generated at the base of the resonance tube were in excess of 811 K (1 000⬚F) for both GOX and nitrogen.

Resonance testing data for metals are described in Ref [59].

In document 0803144709 Oxygen and Oxygen.pdf (Page 50-58)