This test method provides a procedure for performing laboratory tests to evaluate deflagration parameters of dusts.

The data developed by this test method may be used for the purpose of sizing deflagration vents in conjunction with the nomographs published in NFPA 68, ISO 6184/1, or VDI 3673.

The values obtained by this testing technique are specific to the sample tested and the method used and are not to be considered intrinsic material constants.

For hard-to-ignite dusts with low K_St-values, a very strong ignitor may overdrive a 20-L chamber, as discussed in E1515 and Ref 2. If a dust has measurable (nonzero) P_max- and K_St-values with a 5000 or 10 000-J ignitor but not with a 2500-J ignitor in a 20-L chamber, this may be an overdriven system. In this case, it is recommended that the dust be tested with a 10 000-J ignitor in a larger chamber such as a 1-m³ chamber to determine if it is actually explosible.

1.1 This test method is designed to determine the deflagration parameters of a combustible dust-air mixture within a near-spherical closed vessel of 20 L or greater volume. The parameters measured are the maximum pressure and the maximum rate of pressure rise.

1.2 Data obtained from this test method provide a relative measure of deflagration characteristics. The data have also been shown to be applicable to the design of protective measures, such as deflagration venting (1).

1.3 This test method should be used to measure and describe the properties of materials in response to heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire risk of materials, products, or assemblies under actual fire conditions. However, results of this test may be used as elements of a fire risk assessment that takes into account all of the factors that are pertinent to an assessment of the fire hazard of a particular end use.

Note 1—Historically, the evaluation of the deflagration parameters of maximum pressure and maximum rate of pressure rise has been done using a 1.2-L Hartmann Apparatus. Test Method E789, which describes this method, has been withdrawn. The use of data obtained from the test method in the design of explosion protection systems is not recommended.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.