Open a pump rebuild kit and you may find a ring that is not round in cross-section but has four lobes, like a squared-off clover. That is a quad-ring, also called an X-ring, and it is there for reasons.
What the four lobes do
Two sealing points instead of one
A round o-ring contacts each surface along a single line. A quad-ring contacts along two, with a small reservoir of lubricant trapped between them. Two chances to seal instead of one.
It resists rolling
This is the big one. In dynamic service — anywhere a shaft or rod moves — a round o-ring can roll in its groove rather than slide. Rolling twists it, and repeated twisting produces spiral failure. The four-lobed profile resists that.
Less squeeze for the same seal
Quad-rings seal effectively with lower compression, which means less friction and less heat in dynamic applications — and a longer life at the same duty.
Where you will meet one
Pentair specifies a quad-ring on several pumps — 355030, the diffuser seal on the Challenger, SuperFlo, SuperMax, VS and Pinnacle, is a quad-ring. It appears in our rebuild kits for those pumps because substituting a round o-ring there does not work reliably.
See the Challenger guide.
Can you substitute?
Quad-ring where an o-ring is specified: usually harmless, sometimes an upgrade, but check the groove — quad-rings need slightly different geometry to work properly.
O-ring where a quad-ring is specified: avoid it. The equipment maker chose a quad-ring for a reason, usually rolling resistance, and an o-ring in that position tends to fail early and confusingly.
Handling
Quad-rings are more easily damaged on installation than o-rings, because the lobes can be folded over without it being obvious. Seat them carefully, lubricate on assembly, and inspect before closing everything up.
Before you reassemble
Seat every o-ring with a thin film of food-grade silicone. Dry rings pinch and take a set. Aqua Flex Food Grade Silicone Lubricant is what ships in our kits.
O-rings only. Never lubricate the polished faces of a mechanical shaft seal.
Beaver Island Parts Company is not affiliated with, endorsed by, or sponsored by any equipment manufacturer named on this page. All brand names, model numbers and part numbers are the property of their respective owners and are used solely to identify the equipment our replacement parts fit.