X-rings (Quad-Rings)

X-rings (quad rings, four-lobed rings) seal more reliably than O-rings in dynamic applications – they have two sealing lips, lower friction and do not twist in the groove. We have more than 360 items in stock with inside diameters from 1.24 mm to over 240 mm.

Cross-sections 1.78, 2.62, 3.53, 5.33 and 6.99 mm correspond to the AS568 inch series, for some items we also give the number X-102, X-208 etc. Materials NBR 70 for oils and FPM for higher temperatures and chemicals. The size is written as inside diameter x cross-section – e.g. 28.25 x 2.62 NBR 70. Made by NAK and in Taiwan, sizes to DIN 3770. X-rings in stock are shipped immediately, delivery within 1–2 days.

Frequently asked questions

What is the difference between an X-ring and an O-ring?

An X-ring (quad ring) has a four-lobed cross-section instead of the round cross-section of an O-ring. It is self-energising, seals in both directions and does not roll or twist in the groove, so it is mainly suited for dynamic applications such as pistons, piston rods and rotary or oscillating shafts. It is also used for static sealing.

How is the size of an X-ring written?

Just like an O-ring: inside diameter x cross-section in mm and material, for example 28.25 x 2.62 NBR 70. The outside diameter is not stated. The sizes are based on the AS568 inch standard, so some product cards also show the series number, such as X-102 or X-208. Measure the inside diameter and cross-section of the old ring, or the groove dimensions.

Which X-ring material should I choose?

Most X-rings in stock are made of NBR 70, the standard choice for oils and hydraulics and the default material unless stated otherwise. For higher temperatures and chemicals choose FPM (FKM) 70 or 80. We also stock X-rings in NBR 90, HNBR 70 peroxide and silicone-free NBR 70. You can select the material with the filter in the category.

When should I use a back-up ring with an X-ring?

At higher pressure or under dynamic load the X-ring can be extruded into the gap between the parts. To prevent this, a back-up ring is fitted next to it, selected by the X-ring cross-section and the groove size, a single one for pressure from one side and a double one for alternating pressure. You will find back-up rings in the category Back-up rings.

How fast can you deliver X-rings?

We stock over 360 X-rings with inside diameters from 1.24 mm and cross-sections 1.78 to 6.99 mm made by NAK and in Taiwan. X-rings in stock are shipped immediately and delivery takes 1–2 days. Current availability is shown directly for each size. If you cannot find the size you need, send us the designation and we will check whether we can supply it.