What O-ring is this?

[Gary WoodingParticipant @garywooding25363]

My ancient Sievert blow torch gave me a fright today – it burst into flames as I was using it. I was able to blow them out and I wasn't burned, but it was rather scary. The flames originated around the valve, so I dismantled the handle and reckon I need a new o-ring. I've got a box of o-rings, but none of them fit.

Does anybody know which one I need? The photos show the torch handle and valve with the o-ring separated. Sorry about the focus, I blame it on my phone.

[Gary WoodingParticipant @garywooding25363]

[J HancockParticipant @jhancock95746]

Looks like the 'gas' has swollen the O -Ring , whatever size you choose , do make sure it is compatible for

use with the gas you are using.

[Jouke van der VeenParticipant @joukevanderveen72935]

It seems to be a “square”-ring, not an “o”-ring.

Why this shape is applied, I do not know.

Does this ring constantly see gas, also when you do not use the equipment?

[Gary WoodingParticipant @garywooding25363]

It's actually rather difficult to see, but it looks like the ring only sees the gas when the valve is open.

[Jeff DaymanParticipant @jeffdayman43397]

I'd ask a Sievert dealer first about a replacement, but if they don't have them, o-ring suppliers will. If it is actually intended as a square section o-ring, they are available, see link below.

https://www.theoringstore.com/store/index.php?main_page=index&cPath=367_2203

However it may have started out as a normal round section ring and has just compression set to the square groove shape, In that case, I suggest going to an o-ring firm or industrial supply, and test fit a few to get a good fit. If that isn't possible you can buy an assortment of o-rings quite cheap from Ama Zone or E you know and find one. If you get one rated for hydrocarbon / oil service it will be OK with gas. Depending on how hot it gets in the torch, you may want a high heat one. Good luck.

[Michael GilliganParticipant @michaelgilligan61133]

Probably worth grabbing this catalogue whilst it is still available: **LINK**

https://sievert.se/wp-content/uploads/2016/11/Sievert-Catalogue-UK-2016_web.pdf

Several O-rings identified therein.

MichaelG.

[OldironParticipant @oldiron]

Sievert probably still stock spares for that gun Gary.

Are we banned from saying AMAZON & EBAY. ???????

As far as I recall we are allowed to mention these two huge companies in this forum. Why do ppl faff around when it is easier to type the actual name than think of a pseudonim ?

regards

[Gary WoodingParticipant @garywooding25363]

Neither eBay nor Amazon helped much, and TheOringStore are outrageously expensive – it's cheaper to replace the torch. A semi-retired guy at Rothemberger (Sievert) thinks he may have one in a dusty drawer somewhere. He'll let me know next week. Maybe I'll get lucky.

[Les Jones 1Participant @lesjones1]

As you have not given any dimensions of your O ring I estimate from your picture that it is about 6mm ID and about 2mm cross section.
If this is a correct estimate then this is one possible source.

**LINK**

Les.

[Phil H1Participant @philh196021]

Gary,

I am really interested in the answer because I think I have the same or at least a similar torch. Does yours have the economiser trigger? Mine too is ancient but is still an excellent torch. I haven't used mine since the mid 1980s and even then it was ancient.

Phil H

[bernard towersParticipant @bernardtowers37738]

Bearing companies, hydraulic companies and pneumatic companies all use ‘o’ rings drop into one with your torch you’ll be surprised how helpful people can be when you are actually in front of them.

[Gary WoodingParticipant @garywooding25363]

Les,

It actually measures 6.2×2.5, do you suppose a 6×2 would do the job?

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Gary, looks like it is an imperial size of 1/4" x 3/32" and by the looks of the age of your torch is very likely. LPG will leak out of the smallest gaps it can find, so I would try and find one that is much closer to the one you want to replace.

Regards Nick.

[Les Jones 1Participant @lesjones1]

This is one source from ebay. (But you will probably find more as I only spent a few minutes searching.)

**LINK**

Nitrile seems to be a good choice for propane or butane.

Les

[CirclipParticipant @circlip]

Not forced to be a "Standard". Only place to get o-rings for carb on my bike was from carb spares supplier. Similar problem with the one the water governor on boiler.

Regards Ian.

Edited By Circlip on 13/11/2021 10:55:23

[Gary WoodingParticipant @garywooding25363]

Thanks Les,

The link you supplied looks promising, I'll give it a try.

[Brian MorehenParticipant @brianmorehen85290]

Morning Garry , Took my Torch to pieces this morning am certain that this is round at the top mine is quite visible , The next question is this a Metric Size or Imperial Size as both are available.

Regards Bee.m

[Gary WoodingParticipant @garywooding25363]

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), and I couldn't find any metric sizes that were closer leads me to think they are Imperial. That's what I'm going for.

[Gary WoodingParticipant @garywooding25363]

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.

[duncan webster 1Participant @duncanwebster1]

removed

Edited By duncan webster on 28/11/2021 16:42:04

[Nicholas FarrParticipant @nicholasfarr14254]

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 yetParticipant @notdoneityet]

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 GilliganParticipant @michaelgilligan61133]

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 haysomParticipant @martinhaysom48469]

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

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