Rationale Ballot Item #1: The proposed change in ballot item #2 is the requirement for breaking and tearing strength and elongation after heat aging. Modeled after D4637 for EPDM, this proposed change does away with percent retentions and substitutes absolute minimum values. The absolute values are 90% of the minimums for non-heat aged material. Currently, the sample must retain 90% of the original tested value (before heat aging) to meet the requirements in Table 1. The problem with this logic is that at 90% retention, product A may have 500 N (lbf) new and 440 aged and fail (with 88% retention) while product B may have 250 new and 230 aged (92%) and pass, yet A has far superior breaking strength before and after heat aging then product B. An additional test that requires visual inspection has also been proposed to be certain that the membrane will resist water infiltration after exposure to heat (i.e. bend sample around a 3-inch diameter mandrel).
Keywordsflexible sheet; roofing; roofing material; single-ply roofing membrane; thermoplastic polyolefin; TPO; Flexible sheets; Polyolefin (PO)--specifications; Roofing membranes--specifications; Single-ply roof membrane; Thermoplastic roofing/waterproofing materials--specifications;
Negative Votes Need Resolution