Questions About Plumbing O Rings

[br549]

I am hoping the experienced and knowledgeable forum members can help with this non-woodworking subject. I know there are a lot of very smart engineers here, so here goes.

I am trying to replace some O rings on my 37 year old discontinued kitchen faucet. The manufacturer's technical service department has been of limited help.

Looking at the pictures below, I am trying to find replacement seals for the two blue rings that keep the water directed towards the spout. I've had leakage at the top of the body, and am now starting to get leakage at the bottom.

The rings are rectangular in cross section, not circular. Are these perhaps called flat face O rings? In order to measure things, I removed one blue ring only to discover it did not want to stretch or spring back to its original shape.

I had a few hundred words typed explaining the whole saga before trying to re-order the pictures and lost everything I had typed, so will just add the pictures and try to answer any questions you may have.

[thunderbirdbat]

I am not a plumber but I can tell you what I know about O rings from working on large shipboard systems. To find replacements, measure outside diameter, inside diameter and thickness. O rings dry out over time which is why they fail. A lubricant is often used to help keep them from drying out or if dry to help them to become pliable. The lubricant is normally a type of grease based on what the system is being used for. Grease for salt water system is not the same as grease for a fresh water system or steam system. It may be possible to salvage these by use of a food grade grease. We used to rub the grease along all the faces of the O rings to make sure the ring was covered completely then add as much as the possible to the O ring grove. The flat O rings can be replaced by round ones if needed as a temporary fix. Let the O rings soak in the grease for a bit before use. Similar process to using a belt dressing to keep belts from drying out.

[RFGuy]

I agree with everything Brenda said. I don't think those o-rings were originally flat though. I have replaced my fair share of o-ring seals on pool equipment, faucets, etc. and I have seen them get flat like that due to compression over service life. As Brenda suggested remove them and use calipers to approximate the diameter and cross section diameter and find a suitable replacement either at a big box store or online. When the new one is put into service it will deform slightly making it flat, but it typically takes years for that to happen, I believe.

[BuckeyeDennis]

McMaster has a selection of square-profile O-rings, and their parametric product selector is excellent. Plugging your measurements into their selector will probably shed some light on the proper replacement size.

They also give a little info on the various O-ring materials, but I didn’t dig deep enough to figure out if any of their O-rings might be blue.

https://www.mcmaster.com/products/o-rin ... pe~square/

[br549]

Thanks to thunderbirdbat, RFGuy and BuckeyeDennis for your inputs.

I've still gotten no response from three faucet distributors or two O-ring distributors, so am going to try ordering another size O ring, this time with a 1.5 mm cross section and 37 mm inside diameter. It will need to stretch to a 45 mm inside diameter to slide over the brass body, and then snap back to 42 mm inside diameter to fit in the groove. If this amount of stretch seems excessive, please let me know. The O ring that I already tried was the same 37 mm ID but 2.5 mm in cross section, and it seemed to handle the stretching OK ... once installed, it just projected too far to let the faucet body slide over.

The color blue is not important to me, but wondered if that represented a certain type of material, physical properties, hardness, etc. I haven't found any other blue rings in my search ... just black, green, and red.

Will let you know about my success (hopefully) in a few days.

[jsburger]

Check with a reputable plumbing shop that does in house repairs. They should know exactly what you need and probably actually have it or can get it.

[RFGuy]

The color blue is not important to me, but wondered if that represented a certain type of material, physical properties, hardness, etc. I haven't found any other blue rings in my search ... just black, green, and red.

I never knew this, but I guess o-ring color can indicate different materials. I don't see that particular shade of "blue" on the website at the link below, but perhaps it changed over time or maybe there are different ones. Check out the link below:

https://www.callapg.com/blog-oring-colo ... ed%20with.

[Hobbyman2]

Hopefully you have this repair made all ready . if you check with the local hardware store they should have everything you need . a old hardware / plumbing supply store should even have a replacement valve , usually less than 10 bks . I know that some of them even sell O-ring repair kits . the color may represent the diameter of the o-ring

[RexLumber]

I hesitate to weigh in here because there are so many variables. One thing I am confident in saying is that color has nothing to do with o-ring ID, OD, or cross section.

While color alone is not enough to determine material, in my experience, blue o-rings tend to be composed of fluorosilcone.

O-rings often take a set, so as others have noted the cross section may not have been rectangular originally. The o-ring material, the durometer, the design compression, the o-ring gland, etc. all play a roll here.

McMaster is a great resource. So is Apple Rubber.

[br549]

Thanks to all who have replied and offered suggestions.

The faucet has managed to stop leaking, on its own, so if it ain't broke, I'm not going to try to fix it (for now).

I have new O rings to try in case the leak(s) re-appear.