HNBRHydrogenated NBR HNBR FDA FDA 21CFR 177.1680, EU 1935/2004 HNBR DetectableMetal Detectable FDA 21CFR 177.1680, EU1935/2004 HNBR SolidHNBR 90shA HNBR EDAgainst explosive decompression HNBR SoftSofter HNBR 75shA