Finding correct "O" size

Finding correct "O" size

Joined: May 6th, 2017, 12:54 am

October 12th, 2017, 5:39 pm #1

Guys
I need some help,
I am attempting to figure out how measure "O" Rings, and then find the correct sizes etc.

I desperately need the "O" RINGS that fit inside these JT type adapters for the 88/90 gram prefilled Co2 cylinders,

By using the inside and outside dimensions + thickness, of the used "O" rings etc,
I have found NO, "O" rings that are even close, in/with standard "O" ring sites/stores.

Does anyone know for sure what the correct size is?

This "O" ring must seal on the outside/against of the cylinders neck and also seal on the outside of the diameter of the "O" ring against the adapter wall/groove,
when the cylinder is screwed into the adapter and used correctly.

The diameter of the cylinder neck is .455" when starting into the "O" ring and then changes dimensions to .495"/.500" when fully seated.

I would greatly appreciate any help or info for the correct size of "O" ring.

Tia,
Don
Last edited by Nvreloader on October 12th, 2017, 9:32 pm, edited 1 time in total.
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Joined: March 18th, 2011, 6:24 am

October 12th, 2017, 7:08 pm #2

might be handy is stating the gun they are for, also a cross section dimension it is hard to help without one
also any o-rings that are in contact with Co2 they should be urethane because they do not swell--as bad or at all-- by Co2 absorption
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Joined: May 6th, 2017, 12:54 am

October 12th, 2017, 9:31 pm #3

Mike

Thanks, but,

The "O" rings I am needing/wanting do not fit any AR,

It is the INSIDE "O" ring for the JT adapters, that use the 88/90 gram prefilled Co2 cylinders.

I really don't want to remove the "O" ring, as it's the ONLY working one I have, out of 5 adapters.

I am afraid of damaging it, then the QB 79 will be out of service period etc.

I have already looked in several stores, they are either too big/too small in all dimensions.

Tia,
Don
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Joined: March 18th, 2011, 6:24 am

October 12th, 2017, 10:38 pm #4

non working adapters and if you have them take some measurements off them

the O ring store does sell o-ring cord, you can roll your own but there should be something out there that will work
how about Hammerli 850 o-ring they use 88gr cartridges

and look at metric sizes

that all I got at this time


http://www.theoringstore.com/index.php? ... c2563270eb
Last edited by marflow on October 12th, 2017, 10:39 pm, edited 1 time in total.
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Joined: May 20th, 2013, 12:46 am

October 12th, 2017, 10:43 pm #5

Guys
I need some help,
I am attempting to figure out how measure "O" Rings, and then find the correct sizes etc.

I desperately need the "O" RINGS that fit inside these JT type adapters for the 88/90 gram prefilled Co2 cylinders,

By using the inside and outside dimensions + thickness, of the used "O" rings etc,
I have found NO, "O" rings that are even close, in/with standard "O" ring sites/stores.

Does anyone know for sure what the correct size is?

This "O" ring must seal on the outside/against of the cylinders neck and also seal on the outside of the diameter of the "O" ring against the adapter wall/groove,
when the cylinder is screwed into the adapter and used correctly.

The diameter of the cylinder neck is .455" when starting into the "O" ring and then changes dimensions to .495"/.500" when fully seated.

I would greatly appreciate any help or info for the correct size of "O" ring.

Tia,
Don
CO2 will swell and destroy the common, off-the shelf O-rings you find in most places like local hardware stores that sell O-rings for plumbing use/water use. IIRC, like he said, I think you need to use urethane O-rings instead to avoid that problem.

Last edited by ekmeister1 on October 13th, 2017, 4:47 pm, edited 1 time in total.
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Joined: July 28th, 2012, 5:03 am

October 12th, 2017, 11:37 pm #6

Guys
I need some help,
I am attempting to figure out how measure "O" Rings, and then find the correct sizes etc.

I desperately need the "O" RINGS that fit inside these JT type adapters for the 88/90 gram prefilled Co2 cylinders,

By using the inside and outside dimensions + thickness, of the used "O" rings etc,
I have found NO, "O" rings that are even close, in/with standard "O" ring sites/stores.

Does anyone know for sure what the correct size is?

This "O" ring must seal on the outside/against of the cylinders neck and also seal on the outside of the diameter of the "O" ring against the adapter wall/groove,
when the cylinder is screwed into the adapter and used correctly.

The diameter of the cylinder neck is .455" when starting into the "O" ring and then changes dimensions to .495"/.500" when fully seated.

I would greatly appreciate any help or info for the correct size of "O" ring.

Tia,
Don
What you might try is buy a standard and a metric kit for cheap at Harbor Freight find the proper size and test the fit. Once subjected to CO2 these will swell and you will not be able to remove the cylinder until spent and a couple of hours have passed. The buy that size in a compatible material.
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Joined: July 11th, 2001, 6:08 pm

October 13th, 2017, 12:46 am #7

Guys
I need some help,
I am attempting to figure out how measure "O" Rings, and then find the correct sizes etc.

I desperately need the "O" RINGS that fit inside these JT type adapters for the 88/90 gram prefilled Co2 cylinders,

By using the inside and outside dimensions + thickness, of the used "O" rings etc,
I have found NO, "O" rings that are even close, in/with standard "O" ring sites/stores.

Does anyone know for sure what the correct size is?

This "O" ring must seal on the outside/against of the cylinders neck and also seal on the outside of the diameter of the "O" ring against the adapter wall/groove,
when the cylinder is screwed into the adapter and used correctly.

The diameter of the cylinder neck is .455" when starting into the "O" ring and then changes dimensions to .495"/.500" when fully seated.

I would greatly appreciate any help or info for the correct size of "O" ring.

Tia,
Don
They use a different combination of measurements.

For example, you might find a US standard or metric oring here with the correct outside diameter, but it won't have the correct thickness (which will also make the inside diameter measurement wrong), or vice-versa.
Last edited by Diamondback on October 13th, 2017, 12:49 am, edited 1 time in total.
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Joined: February 25th, 2009, 1:05 pm

October 13th, 2017, 12:47 am #8

What you might try is buy a standard and a metric kit for cheap at Harbor Freight find the proper size and test the fit. Once subjected to CO2 these will swell and you will not be able to remove the cylinder until spent and a couple of hours have passed. The buy that size in a compatible material.
I used crosman valve o ring 112 and it's exact as the one that came out of the adaptor. Used 90D urethane. Got it here >> http://www.theoringstore.com/index.php? ... s_id=16242
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Joined: May 6th, 2017, 12:54 am

October 13th, 2017, 4:55 pm #9

Thanks for the info,
I have ordered some.

Tia,
Don
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Joined: April 18th, 2001, 2:28 am

October 13th, 2017, 5:38 pm #10

Guys
I need some help,
I am attempting to figure out how measure "O" Rings, and then find the correct sizes etc.

I desperately need the "O" RINGS that fit inside these JT type adapters for the 88/90 gram prefilled Co2 cylinders,

By using the inside and outside dimensions + thickness, of the used "O" rings etc,
I have found NO, "O" rings that are even close, in/with standard "O" ring sites/stores.

Does anyone know for sure what the correct size is?

This "O" ring must seal on the outside/against of the cylinders neck and also seal on the outside of the diameter of the "O" ring against the adapter wall/groove,
when the cylinder is screwed into the adapter and used correctly.

The diameter of the cylinder neck is .455" when starting into the "O" ring and then changes dimensions to .495"/.500" when fully seated.

I would greatly appreciate any help or info for the correct size of "O" ring.

Tia,
Don
This is only an indirect answer to your question, but here goes...

There are tons of places to buy online, that have a lot more options than you will find in a local store--different sizes, materials, etc., etc. My current favorite is The O-Ring Store at:

http://www.theoringstore.com/

Among other features there, are descriptions of various materials and their applications, how to measure sizes, etc., etc.

An in-place O-ring is quite hard to measure as you have described; but O-rings are so ridiculously cheap at these places that you don't really have to be too precise. Make your best guess as to the size, then order some that are incrementally larger and smaller. You can get dozens for pocket change...I've built up a nice little stockpile of potential springer breech seals that way.
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