Material Selection for O-ring Seals

It needs to consider comprehensively about the working environment, medium features, performance request and the cost when choosing the right material for oring seals, below are the specific analysis procedures and application scenarios of regular materials.

1. Confirm the medium type

•Corrosive Mediums: as acid, alkali, solvents etc. Need choose anti-chemical material(such as PTFE, FFKM)。

•Oily Mediums: as hydraulic oil, lubricant etc. Prior selection of NBR or FKM.

•Gas Mediums: need to focus on airtightness, such as VMQ or FKM

•Water/Gas: EPDM or VMQ excellent anti-water features

2. Temperature Range

Low temperature(-50 C below): Silicone(VMQ) or fluororubber(FKM) good low temperature performance

High temperature(150 C above): PTFE, FFKM or VMQ.

Extreme temperature: Need to ensure if material become hard at high temperature and become brittle at low temperature.

3. Pressure grade

High Pressure Scenario

Choose the material of high hardness, big elastic module or metal skeleton oring seals

Dynamic Seals

Friction coefficient needs to be considered, for example, polyurethane has good wear resistance but high friction force

4. Motivation Status

Static sealing

Almost all the material are available, but need to focus on compression set rate.

Dynamic sealing

Choose wear-resistant and low friction materials(like PTFE, silicone rubber)

5. Consideration of special request

•Food/Medical Industry: comply with FDA, NSF certificate, prior selection of VMQ or PTFE.

•Avoid using materials containing sulfur or heavy metals (such as certain NBR formulations)

•Environment Requirements: avoid using materials containing plasticizers or harmful substances (such as certain PVC sealing rings).

choose recyclable or biodegradable materials (such as specially modified rubber)

•Cost sensitive scenarios: low temperature/low pressure environment, NBR or EPDM. For short-term use or low demand scenarios, butyl rubber (IIR) or chloroprene rubber (CR).