I have owned a Townsend and Coxson Double Burner Stove for a number of years I had to stop using it due to the NRV failing and letting petrol into the priming tube. Opening it up I found that the NRV was made out of cork, I replaced that with a Viton Tilley NRV off ebay which soon turned to mush I have just bought some more NRV washers off another supplier hoping for better things Question, is Viton suitable for use with petrol ? I need to replace the the washer on the filler cap and want to buy a sheet off Viton to do that.
Hi @andyfoulds , Viton (in its correct grade) is about the best one can get. Nitrile has also been used, but often in a wrong grade causing seals & pips etc. to swell/being eaten by liquid fuel. Ross, who owns The Fettlebox has run extensive trials to find the best material to make seals etc. Only buy from a source you can trust! (And don't use any "new old stock" stuff, as any and all rubber also deteriorates with age!). Best regards, Wim
Many thanks I have had it lit again but its still letting petrol into the pump so fuel is by passing nrv It might be that the the viton isn't thick enough, thats supposition till I have another look.
Hi @andyfoulds , if you can't find anything wrong with the NRV itself also check the pump tube for cracks. Not very common, but it sometimes happens. Also the soldering of the tube's bottom (where the NRV goes into) could be damaged. Best regards, and good luck, Wim
@andyfoulds What @Wim ’s said makes sense. I’ve one of those T&C stoves and at least the pump tube’s removable to do the checking Wim’s recommended. I’m pretty sure the NRV seal in mine isn’t viton, but some grade of nitrile I was using at the time - which is still good. Viton that ‘turned to mush’ as yours did isn’t something I’ve experienced but sometimes it’s been of a grade that’s too hard and not flexible enough to make a good seal with the spring it’s mated to. Spring tension can be quite critical in such circumstances, but too stiff a spring makes the pump action lousy, so a workable compromise has to be reached. Of course some nitrile turns to mush in petrol. Don’t ask me which grade/brand of viton/nitrile will do the job, I’ve just plumped for what’s been available and so far it’s worked. Good luck with the annoying fault! John
I will have another check over of the Stove and come back and let you know how I get on. Sorry for the delay in updating this thread
I've also found that the harder viton doesn't work as well for nrv pips. The 70 or 80 duro stuff is just too hard for the tiny nrv spring to force a good seal. I've been using the 40 or 50 duro stuff with good results.
Great stove, thanks for sharing it with us. No worries at all on the delay, most of us are afflicted with the curse of having a job and life outside of stoves. We understand.
This stove runs on petrol. It was designed to run on milspec fuel so should work with any decent quality car petrol. However, it is recommended to use non-doped fuel like Coleman fuel, panel wipe, Aspen4, brake cleaner etc.. @kongrit ratanakanahutanon
