VMQ (Silicone) O-rings

VMQ (silicone) is the elastomer with the widest temperature range in the O-ring offering: it works reliably from −60 to +200 °C (briefly up to +230 °C) and its usual hardness is around 70 ShA. The material keeps its flexibility even at the extremes of this range, which makes it a sure choice where other materials already stiffen or soften. It's physiologically inert, with no taste or smell, and therefore suitable for food processing and medicine — food-safe compounds meet, for example, FDA 21 CFR 177.2600.

VMQ O-rings resist water, dry hot and cold air alike, ozone, UV and many polar media well, and they excel in electrical-insulation properties. It's precisely the exceptional temperature range and the physiological inertness that are the reasons silicone is deployed in food processing, medicine and anywhere hot or very cold air is at work. For contact with food, though, what's decisive is whether the specific compound carries the relevant certification — silicone on its own doesn't automatically guarantee it.

Watch the limits, though. VMQ isn't suitable for high-pressure steam (silicone hydrolyses), for permanent contact with mineral oils and fuels, or for dynamic or abrasive applications, because it has low mechanical strength and poor resistance to tearing and wear. On moving joints it therefore wears out quickly — there, choose FKM, and for oils at higher temperature, fluorosilicone (FVMQ), which combines silicone's temperature range with resistance to fuels.

Typical uses are found in food processing and medicine, in static seals across a wide temperature range, in electrical-insulation applications and anywhere hot air is at work. Compared with the other materials, VMQ's strong suit is its temperature range and inertness, and its weak point is mechanical resistance. Choose a silicone O-ring, then, when you need to handle extreme temperatures and contact with food in static joints — not for moving seals or permanent contact with oils.

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