hi Gary i'm not able to braze or solder but i reckon they could be shortened,but it would probably be easier to blank an old pump cap and swap over when you want to use it,these valves have a locking nut on top so once pressure is inside the tank it is going to stay there,i might well take one set up when i go camping as you say it would work even if the nrv was shot or the pump leather failed, it will easily hold back a 120-130 psi so normal tank pressure would be no probs,but being a bit cautious i'd only use paraffin to be safe,it would be nice to pump the stove with my bike pump though and know what pressure i'm running at
Something just occured to me. I was at the mechanic the other day with one of our POS dodge vans that was short on some coolant. The mechanic has a device for checking the coolant system which looked like a pump that fitted directly onto the radiator and he pumped it up and watched the gauge to see if the pressure dropped (indicating a leak). It occurs to me that this is exactly the type of device needed to check these caps. If someone could fabricate some sort of adapter ring that was threaded on one end for the standard radiator fitting and with a threaded spot for a fuel cap on the other. I am such a nerd for thiking of that.
As I already sad, your valve might be fuel resistent (benzine) but it works not very good at cold. standart stove NRV is much better. Georgiy Salnikov used several types of bycicle valves(and your type to), they are not so reliable in your conditions as stoves NRV are. The most reliable and convinient way is to use stove NRV and bycicle pump.
Have a look at the EZ pump device, for Petromax-type pressure lanterns, on the Pelam site: http://www.pelam.de/product_info.php?cPath=30_52_98&products_id=164 Regards, Kerophile.
hi Kerophile thanks for the link,but it won't fit a 111 will it? as the Petromax takes a larger pump iirc it's been at least 20 years since i had mine,looks like i reinvented the wheel
To answer Gary's question a few posts back I also habitually disassemble the SRV and replace the nitrile on any SRV equipped stoves that are new to me. I'd much rather be assured that it isn't going to leak due to hardened nitrile and is freed up to do it's job if excees pressure does homehow develop. Whether I get it back together again within +/- 10 PSI I really don't care - I personally don't believe it makes much of a difference. Again, this is not a recommendation, just an account of my personal approach! BTW - I had a quick troll through a small selection of English language manufacturers instruction leaflets published on the site, and in my file at home, I and didn't come across any dire warnings of death and destruction if you dick around with the SRV. In fact fact they don't seem to be mentioned at all, in the same way the NRV is never mentioned.
hi Graham after using the tester i think your right about replacing the pip, from now on it's going to be a standard part of my fettles at least i'll know that the srv isn't jammed or working with a hard seal,i think i'd sooner trust my fettling than a 30/40 year old pip
Interesting thread this, I might well be looking out for those Bontrager valves to do a bit of testing. Just a thought about cutting down the stem . . . when used for it's intended purpose isn't that where the valve is ?
I'm an idiot, you don't need to shorten the valve. Just trap the pump cap further up the threads using two nuts, a washer and a nitrile washer.
In all instances , DO an underwater pressure test. Sealing a male threaded stub , going thru a bulkhead , is a bugger of a job ( Homebrew beer experience :frown: ) Nick
This has been a very interesting thread. Good job, fellers! But, I have a question and my apologies if this is stupid or ignorant or misinformed. Please set me straight. Optimus made a little pump and a special filler cap that went with it so that one could build pressure in a stove under cold weather (?) conditions. Now, in order to allow pumped air to enter the tank and pressurize it, I'm of the mind that the cap could not act as a SRV because the spring and pip are in place in exactly the opposite direction they need to be. Sooooooo.... wouldn't use of such a cap and little pump make the tank a "potential bomb"? And, if so, what in the world were they thinking at Optimus?!! For what it's worth, I service my SRV's. I'm careful not to monkey with the spring. I figure a SRV that works at a slightly different pressure is better than one that will not work at all. I've also had tanks pressurized up to 120psi without failure. Also, for what it's worth, your mileage may vary, don't try this at home, etc. Cheers, Gary
Gary That cap has two "valves" one to allow air in under the pressure created by the pump, and another to allow air out if the pressure becomes too high. There is a diagram here somewhere I'll try and find it.
Oh. Well, I obviously didn't think that one through! Thank you Gary for breaking the obvious to me in a gentle manner. I guess it would have to have two to be safe. That must be an interesting feat of engineering. I'll poke around and see if I can't find the diagram. I can't grasp how that could be done, though I'm sure you're right about it. The pump and special cap were fresh on my mind as a cap and pump set fetched over $65USD on US eBay over the weekend. Maybe the price is indicative of the engineering as well as the rarity. I suspect I shan't own one anytime soon. Thanks again. Cheers, Gary
hi Gary Knight84 posted one taken apart earlier in this thread,you can still buy them from a&h and basecamp there good they transform a 8r into a very powerful little beast,i like mine and wouldn't be without them
hi Gary been thinking about what you have said,the valves are chrome plated brass couldn't you just solder the bottom nut in situ on the valve stem, that would then give you an air tight seal when clamped against the nitrile gasket,i've seen these type valves with a removable core might be better getting one of those then you could remove it while soldering
Thanks so much for the tip on the midi pump and cap, Parra. Don't know why I've assumed they were long out of production but sure enough, there they are at Base-Camp! All those little pieces that Knight posted didn't click with me as the midi cap never having had one. But I think I've figured out how it works from studying the parts - ingenious indeed! A new stove toy to acquire. This place is great! Thanks again! Gary
Hi That's the diagram I was thinking of. I have obtained some knackered inner tubes with that style of valve from a friend. I will start the experimentation as soon as I fix the knocking strut on the Sharan. :frown:
Thanks Arne! That's an excellent link-up. I've added it to my favorite topics. Nice job on the diagram you drew. I've got a midi pump and some caps on order and look forward to trying them out. Cheers, Gary
Thanks Gary. Drawing could certainly have been better. Was made in a hurry. But I think it is good enough to show how the mini/midi pump cap works.
