Frequently Asked Questions — PVMQ O-Rings
What is PVMQ phenyl silicone rubber?
PVMQ (Phenyl Vinyl Methyl Silicone) is a silicone elastomer with phenyl groups incorporated into the Si-O backbone. These bulky substituents disrupt polymer chain crystallisation at low temperatures, preventing the brittleness that limits standard VMQ silicone. The result is the widest operating temperature range of any commercial o-ring elastomer.
What temperature range can PVMQ o-rings handle?
PVMQ o-rings operate from −100 °C to +200 °C — an operating window no other standard sealing material can match. Standard VMQ silicone becomes brittle below −60 °C, whereas PVMQ remains elastic and sealing well below this point, making it the only practical elastomeric choice for cryogenic applications.
What chemicals is PVMQ resistant to?
PVMQ has the same chemical resistance profile as standard VMQ silicone: good resistance to hot air, ozone, UV, water, mild acids and bases at low concentrations, and oxidising media. The primary differentiator over VMQ is ultra-low-temperature capability, not enhanced chemical resistance. Petroleum oils, fuels, and concentrated acids still cause degradation.
What are typical applications for PVMQ o-rings?
PVMQ o-rings are used in aerospace and defence systems requiring cryogenic sealing (liquid oxygen, liquid nitrogen, liquid hydrogen fuel systems), high-altitude aircraft equipment, satellite and space vehicle components, laboratory cryogenic instrumentation, and superconducting magnet systems where operating temperatures below −60 °C are encountered.