What O-ring is this?

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

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

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.

.

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.

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.

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.

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.

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.

Very happy to bow to your evident wisdom, Nick

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

MichaelG.

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.

Thanks, Nick

MichaelG.