1.1 This specification establishes the criteria for acceptance, prior to installation, of vitrified clay filter block used in trickling filters for the treatment of sewage and industrial wastes.

1.2 In developing the metric conversions used in the standards under the jurisdiction of C-4, recognition has been made of the variable nature of clays so that neither "soft" nor "hard" conversions, as they are defined in Practice E380, have been made. For example, the inch is considered to be 25 mm instead of 25.4 mm.

1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.

1.4 The following precautionary caveat pertains only to the test method portions shown in Annexes A1 through A3. 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.