Quad rings

How to select the size

Groove dimensions are the same as an O-ring of the same size — they are often interchangeable without rework.

The advantage shows where an O-ring rolls or creeps, typically in slow reciprocating motion.

Materials

The material is chosen by medium and temperature, not by price:

• NBR — the standard for mineral oil, −30…+100 °C. Most common and least expensive.
• FKM (Viton) — up to +200 °C, aggressive media, brake fluid. Three to five times the price of NBR.
• PU (polyurethane) — high pressure and abrasion, but not above +80 °C.
• PTFE — chemicals, very low friction, but poor under compression without support.
• EPDM — water, steam, glycol-based brake fluid. Not compatible with oil.

Common fitting mistakes

Three mistakes that make a new seal leak within a day:

1. Damaged lip during fitting. The seal is pushed over threads or splines without a sleeve — the lip is cut and you cannot see it.
2. Measuring a worn part. The old ring has lost its shape, so the new size does not seat in the groove.
3. No back-up ring. Above 160 bar the seal extrudes into the gap.

Frequently asked questions

Can an O-ring be replaced by a quad ring?
Yes, when the groove size matches. It is a common upgrade where a plain O-ring rolls in service.

Is a quad ring more expensive?
Usually 20–40% more. In slow-moving joints the difference pays back in service life.

Which materials are available?
NBR and FKM. EPDM for water and steam on request.