Flash point
Flash point. (1) Flash point means the minimum temperature at which a liquid gives off vapor within a test vessel in sufficient concentration to form an ignitable mixture with air near the surface of the liquid. It shall be determined as follows:
(i) For a homogeneous, single-phase, liquid having a viscosity less than 45 S.U.S. at 38 °C (100 °F) that does not form a surface film while under test, one of the following test procedures shall be used:
(A) Standard Method of Test for Flash Point by Tag Closed Cup Tester, (ASTM D 56) (IBR; see § 171.7 of this subchapter);
(B) Standard Test Methods for Flash Point of Liquids by Small Scale Closed-Cup Apparatus, (ASTM D 3278) (IBR; see § 171.7 of this subchapter); or
(C) Standard Test Methods for Flash Point by Small Scale Closed Tester, (ASTM D 3828) (IBR; see § 171.7 of this subchapter).
(ii) For a liquid other than one meeting all the criteria of paragraph (c)(1)(i) of this section, one of the following test procedures must be used:
(A) Standard Test Methods for Flash Point by Pensky-Martens Closed Cup Tester, (ASTM D 93) (IBR; see § 171.7 of this subchapter). For cutback asphalt, use Method B of ASTM D 93 or alternative tests authorized in this standard;
(B) Standard Test Methods for Flash Point of Liquids by Small Scale Closed-Cup Apparatus (ASTM D 3278) (IBR; see § 171.7 of this subchapter);
(C) Determination of Flash/No Flash—Closed Cup Equilibrium Method (ISO 1516) (IBR; see § 171.7 of this subchapter);
(D) Determination of Flash point—Closed Cup Equilibrium Method (ISO 1523) (IBR; see § 171.7 of this subchapter);
(E) Determination of Flash Point—Pensky-Martens Closed Cup Method (ISO 2719) (IBR; see § 171.7 of this subchapter);
(F) Determination of Flash Point—Rapid Equilibrium Closed Cup Method (ISO 3679) (IBR; see § 171.7 of this subchapter);
(G) Determination of Flash/No Flash—Rapid Equilibrium Closed Cup Method (ISO 3680) (IBR; see § 171.7 of this subchapter); or
(H) Determination of Flash Point—Abel Closed-Cup Method (ISO 13736) (IBR; see § 171.7 of this subchapter).
(2) For a liquid that is a mixture of compounds that have different volatility and flash points, its flash point shall be determined as specified in paragraph (c)(1) of this section, on the material in the form in which it is to be shipped. If it is determined by this test that the flash point is higher than −7 °C (20 °F) a second test shall be made as follows: a portion of the mixture shall be placed in an open beaker (or similar container) of such dimensions that the height of the liquid can be adjusted so that the ratio of the volume of the liquid to the exposed surface area is 6 to one. The liquid shall be allowed to evaporate under ambient pressure and temperature (20 to 25 °C (68 to 77 °F)) for a period of 4 hours or until 10 percent by volume has evaporated, whichever comes first. A flash point is then run on a portion of the liquid remaining in the evaporation container and the lower of the two flash points shall be the flash point of the material.