O-rings

[Gadgeteer]

I have a pressure washer that keeps blowing out the o-rings on the unloader valve. I'm wondering what type rings are used in high pressure applications. Rings are 1/4" and 3/8" ID.

Thanks for any info.

[tenkara500]

I'm no pressure washer expert user but it looks like there are several search returns for high pressure o-rings that appear to be specific to pressure washers- maybe the material they are made of makes them more durable?

https://www.meyerspressurecleaners.c...s-super-viton/

[Ironman]

Originally Posted by Gadgeteer

I have a pressure washer that keeps blowing out the o-rings on the unloader valve. I'm wondering what type rings are used in high pressure applications. Rings are 1/4" and 3/8" ID.

Thanks for any info.

What rings are you using now? Are they 90 durometer?
Any viton ring should withstand a pressure washer unless something else is going on, such as a an unloader valve worn beyond specs.

[GWIZ]

Originally Posted by Ironman

What rings are you using now? Are they 90 durometer?
Any viton ring should withstand a pressure washer unless something else is going on, such as a an unloader valve worn beyond specs.

I had to go with viton and as Gary noted the durometer number, the viton that I picked up were at least twice has hard as the standard O-rings.

[dubby]

Way back in the day when I was experimenting with my fishing lure injectors, I snatched up the o-ring kits from harbor freight. I have never been able to run through them all, but for $10 even today it's a deal. Once I found the actual size I needed, I'd order batches of the correct ones from McMaster.

Like everything else chicom, I found that the HF ones were of different quality and in some cases that has proven more useful simply because they were harder/stiffer.

[Shade Tree Welder]

Okay there are a couple of things you need to know about o-rings.

1. ID and width of the ring (aka the diameter of the cross section of the ring.)

2. The hardness of the ring "Durometer" is common measurement, but you
also have to know the scale you are on. The Shore scales of hardness are A,
B, C, D etc ad nauseam... A and D are the most common. I cannot recall
ever seeing B, C or the others being used in a specification, but be aware
they exist. Gerry reference to a 90 is on the A scale, which is a good
recommendation.

3. Also in high pressure application it is common for an o-ring to have a
backup washer or ring that eliminates or minimizes extrusion of the ring.
Did this originally have those?

4. Also pick a material that is good with water. Viton is a good option, also
EDPM. Buna-N is good if you have a highly cross linked form of BUNA-N, but
you will not likely know if it is.

Back in the 90's when working at Castrol I did an extensive study and report
on metalworking fluids, hydraulic oils and slideway lubricants and their effect
on seals, elastomers and polymers. Buna-N not a good option. Viton was
great but at the time not common for use on machine tools. EDPM was good
with the water chemistry but suffered a bit with some of the lubricants.
Parker-Hannifin did a great job supporting me/Castrol with materials and test
methods.


https://www.mcmaster.com/products/o-rings/

https://www.mcmaster.com/products/o-ring-backup-rings/

https://en.wikipedia.org/wiki/Shore_durometer

[greywynd]

Temperatures also play into this, some rubbers get softer as they warm up.

Is this a hot or cold water pressure washer?


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[Gadgeteer]

Wow! All good info. This is for cold water application, only. I'm trying to order rings from MPC.

Thanks, guys!

[arizonian]

Originally Posted by dubby

Way back in the day when I was experimenting with my fishing lure injectors, I snatched up the o-ring kits from harbor freight. I have never been able to run through them all, but for $10 even today it's a deal. Once I found the actual size I needed, I'd order batches of the correct ones from McMaster.

Like everything else chicom, I found that the HF ones were of different quality and in some cases that has proven more useful simply because they were harder/stiffer.

I'll stick my 2¢ in here. Seems HF O-rings are not only of dubious quality, they seem to be made just a touch on the small size. An O-ring from HF didn't seal on my 03 6.0, but the same O-ring from a parts store sealed up like it should. You could tell by the difference in force when inserting the heater hose coolant tube into the manifold.

[greywynd]

Originally Posted by arizonian

I'll stick my 2¢ in here. Seems HF O-rings are not only of dubious quality, they seem to be made just a touch on the small size. An O-ring from HF didn't seal on my 03 6.0, but the same O-ring from a parts store sealed up like it should. You could tell by the difference in force when inserting the heater hose coolant tube into the manifold.

It’s possible the HF O-rings may also be metric. Similar sizes but not the same.


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