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What O-ring is this?

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Nicholas Farr28/11/2021 18:30:42
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3330 forum posts
1531 photos

Hi Gary, 1/16" is a fair bit smaller than the 2.5mm you mentioned, so maybe 5/64" might be closer, perhaps This one might be better. Something went wrong, try This one

Regards Nick.

Edited By Nicholas Farr on 28/11/2021 18:34:24

not done it yet28/11/2021 18:49:58
6744 forum posts
20 photos

I’m not sure why anyone would even expect O rings on a Sivert torch would be anything other than metric.

Edited By not done it yet on 28/11/2021 18:50:21

Michael Gilligan28/11/2021 23:36:04
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20108 forum posts
1043 photos

Gary,

They may, of course, have revised the design over time … but this page from Cousins looks useful:

**LINK**

https://www.cousinsuk.com/product/handle-replacement-parts?code=B0123

MichaelG.

martin haysom29/11/2021 09:14:14
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90 forum posts
Posted by Gary Wooding on 28/11/2021 14:31:08:

I opted for the 1/4"x3/32" size (had to buy 5) but it turned out to be a mite too big - the valve actually went in, but was far too tight. I probable something closer to 1/4"x1/16" will be OK.

sometime the ring needs some lube

Michael Gilligan29/11/2021 10:03:38
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20108 forum posts
1043 photos
Posted by Gary Wooding on 14/11/2021 13:39:45:

Hi Brian,

Nick's observations that my measured dimensions (6.2mm x 2.4mm) are very close to 1/4"x3/32" (6.35mmx2.38mm) …

.

It may well be an example of ‘rounded metrication’ … but please note that some of the O-Rings listed in the Sievert catalogue that I linked earlier are stated to have 2.4mm diameter.

MichaelG.

Gary Wooding29/11/2021 12:47:42
969 forum posts
254 photos

This is a scale sketch of the groove into which it must fit. The hole it goes into is 10mm diam.

o-ring groove.jpg

Michael Gilligan29/11/2021 12:55:40
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20108 forum posts
1043 photos
Posted by Gary Wooding on 29/11/2021 12:47:42:

This is a scale sketch of the groove into which it must fit. The hole it goes into is 10mm diam.

.

There’s not much hope of successfully using a 2.4mm [ish] O-Ring in a 2mm groove

MichaelG.

not done it yet29/11/2021 13:47:58
6744 forum posts
20 photos

So what would be wrong with a 6mm ID X 2mm?

I have 20 of them in one of my 3 boxes of O rings.

Material selection may be required.

Nicholas Farr29/11/2021 16:59:02
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3330 forum posts
1531 photos

Hi Gary, it's a job to tell from the photo that shows your "O" ring, but to me it looks more of a rectangular section rather than a true "O" ring, which having dealt with some gas valves in my time, I would have expected it to be a rectangular section with a slightly convexed outer edge. So I've had a look at mine and that is exactly how mine is.

torch valve.jpg

Although my one is only 7.81mm outside diameter on the stem with a 3mm gap and 4.2mm diameter in the gap. As can be seen, it does have a very slight convexed outside edge, so you may find you need to get a correct replacement for yours.

As I've said LPG gas leaks through very small gaps and is probably why a broader sealing ring is used. Although I had to disengage the threaded portion on the steam of mine, the drag of the seal was to great to just pull it out with my figures on the stem and I had to reattach the knob to get sufficient grip to get it out.

Regards Nick.

Michael Gilligan29/11/2021 17:51:14
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20108 forum posts
1043 photos

Very happy to bow to your evident wisdom, Nick yes

… What do you make of the items illustrated on the Cousins page that I linked earlier ?

MichaelG.

Nicholas Farr29/11/2021 18:36:10
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3330 forum posts
1531 photos

Hi MichaelG, I have to say that the rings in those do look like a conventional "O" ring shape and one of the three shown looks as if it would fit mine should I need to replace mine and for the price of them I would rather buy one of those than faff about trying to find a new ring, however given the age of mine, I would probably buy a new torch altogether, but I am aware that not everyone can make that choice. It's a long while now since I've had to service such valves and undoubtedly things have changed with more modern materials and new ideas are used, I suppose that they could compress into the shape of my one without any distress to it.

Regards Nick.

Michael Gilligan29/11/2021 19:45:30
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20108 forum posts
1043 photos

Thanks, Nick

MichaelG.

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