scope:

This test method establishes a procedure to determine the percent silica-producing volatiles present in heat cure silicone or one component RTV sealant. Silica producing volatiles are contributors to the fouling of oxygen sensor systems used in the control of vehicle emissions. As a contributing source of contamination, the volatile potential of silicone can be accurately monitored by the use of this procedure. Utilizing this method in conjunction with a realistic maximum volatility tolerance level for end use material can help minimize the risk of oxygen sensor disfunction.

The procedure consists of 4 basic steps: 1) the silicone is cured to its elastomeric form, 2) the volatiles are extracted from the cured material, 3) the extract is separated and measured by gas chromatography (GC) and 4) the GC results are quantified using a siloxane calibration. The volatile silicones from a commercial silicone are primarily cycle dimethyl-siloxane. Other species present having GC retention times similar to those of the cyclics are assumed to be silicone as well.

Safety.

This method may involve hazardous materials, operations and equipment. This procedure does not propose to address all the safety problems associated with its use. Is the responsibility of the user of this procedure to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.