"Standard Test Procedure (STP): Determination of Lens Fogging: Full Facepiece Chemical, Biological, Radiological, and Nuclear (CBRN) Air-Purifying Respirator (APR)"

This test establishes the procedures for ensuring that the level of protection provided by the degree of lens fogging of the Full Facepiece Chemical Biological Radiological and Nuclear (CBRN) Air-Purifying Respirators (APR) submitted for Approval, Extension of Approval, or examined during Certified Product Audits, meet the minimum certification standards set forth in this Standard Test Procedure (STP) as prescribed by 42 CFR, Part 84, Subpart G, Section 84.63(a)(c)(d); Volume 60, Number 110, June 8, 1995. The purpose of this test is to subject the CBRN APR to a low temperature environmental condition in order to test the occurrence and extent of lens fogging while the item is worn by a human subject. Respirator lens fogging can be defined as the condensation of water vapor on the internal surface of the lenses to such a degree that vision becomes impaired. Factors that influence fogging of the full facepiece APR lenses or visor include environmental conditions, moisture trapping within the facepiece, work intensity, airflow dynamics within the facepiece, and the optical surface of the lenses or visor. The procedures described herein are intended to test the APR for failure of manufacturers’ design characteristics for preventing obstruction of vision due to significant lens/visor fogging when subjected to potentially harsh conditions by a user. This procedure may be used for other types of Respiratory Protective Devices (RPD): Refer to the primary Statement of Standard of that RPD for the Durability Conditioning requirements. This STP describes the Determination of Lens Fogging on Full Facepiece Chemical Biological Radiological and Nuclear (CBRN) Air-Purifying Respirators (APR) test in sufficient detail that a person knowledgeable in the appropriate technical field can conduct the test and determine whether or not the product passes testing.