The Steamboating Forum

At last weekend's meet at Siltcoos, I learned of an O ring called a quad O ring. The cross section of this O ring looks like a four leaf clover. Given my description, assume the O ring has a cross section 3/32 "square".

It's time to build a new piston-displacement feed water pump for our boat and instead of my usual packing I want to try this new ring. The seal dealer gave me a booklet which showed dimensions to machine the groove but I'm not sure the sketch is appropriate for my uses.

I'm planning to weld and face a flat plate at the piston end of the bonze cylinder with a second, grooved plate facing the first plate to hold the ring in place. I'm not sure how 'wide' (deep) to make this groove to ensure when pulling the two plates together the ring will 'expand' against the stainless steel piston.

If you have experience with this type of O ring can you please respond with your thoughts on my plans. Thank you.

It is my understanding that the "X" or "Quad" type rings are used for low pressure differential rotary shaft seals, their advantage being two, rather than one contact surface. The "X" type rings would probably be OK for feed pump service in our relatively low pressure applications (100 - 200 psi), but check that they are rated for this duty. The groove dimension specifications are found on any number of websites selling "O" rings, and the "X" rings use the same standards.

I have used conventional "O' rings for feed pump service with good reliability, and I fit two "O" rings on the piston, about 1/4 inch apart, with waterproof grease between the two rings. The pump cylinder is a piece of brass pipe, with no machining or finishing on the bore.

It appears that you are using a plunger type pump, where the packings are stationary, rather than mounted on the piston. In this case the "X" type ring could provide a sheltered space for grease between the two sealing contact points of the "X" ring.

I found this website which has interesting details on these types of O Rings:

http://www.pressureseal.com/4-7.htm

Quad seals are also called x-rings/double acting seal, helps to reduce frictional force. Quad rings are OK for feed pump service since the application runs in low pressure. A quick search on Google came up with this result http://ismat.in/Rubber-Quad-Rings.html, very interesting information is given about quad rings and o-rings.