Well, my beloved Carlson and Sons Marine Stove decided to not work again. Got it up and running and it has served well for a couple years now. But, now the nrv decided to fail again. Im guessing the spring pushing the nrv pip is just too weak after all these years. Its a delicate little thing. Ive tried every bit of nitrile I have and nothing will work. So, either I find a spring to replace the old one and see if that will do it or get a whole new pump/tank. Any suggestions from those more experienced than myself is greatly appreciated. Somewhere here on CCS land is a post and pics of the pump assembly on my particular stove. The nrv assembly on my stove is a bit different from Berniedawg's stove. Also, Im pretty sure the failure of the nrv to keep a seal is not due to the valve surface having any dents or dinks on it. Im pretty sure its smooth and undamaged enough. Im pretty sure its from a weak spring. I have no idea how to go about finding or selecting a spring to replace the old one. I have been thinking of getting a whole new fuel tank and pump. Something like this: Chemical Sprayer Tank. Or I've recently been considering getting an old Coleman fuel tank and frankie'ing it but I'm not sure. Either way the fuel line will need to be compatible with or adaptable to 1/4" OD copper pipe / brass compression fittings. If you have any ideas please offer them. If the OD of the main shaft of a fuel delivery line on a Coleman two burner stove is 1/4" or compatible with some other size of standard compression fittings such that I can adapt it to 1/4" fittings, I may just go that route. Also, Im curious about the specs of the threading on a Coleman fuel tank where the fuel delivery line screws down into. If I could find a fitting to go in there then adapt to 1/4" compression fittings that would be an option too. Any help is appreciated. I just want to get my stove running again and don't really care how.
Make my own spring. Brilliant... Thanks Kero. Im not sure how to determine the right gauge of brass wire to use though. I dont have a micrometer scale. The part is not Swedish made. No telling what Carlson and Sons may have used or even if the spring in there is the original.
It would have to be a fat pen. The nrv spring is at least 4mm dia. Its also only 11 ml long. Unless you're suggesting reshaping the pen's spring, which is an idea to consider. Next time, my Radius 21 needs refueled, I ought to pull the nrv out of it and compare springs.
If you are using the nitrile I sent you ages ago that will be a problem. It has not stood the test of time on my stoves. I use viton for nrv pips now. Dan
Well, my Optimus 510 finally arrived and the nrv spring in it crumbled into multiple pieces as soon as I took it out to inspect it. It was likely weakened from the lead oxidation from the lead nrv washer from the looks of it. So, I have two nrv springs to replace now. Kerophile's suggestion to make my own nrv spring really is quite a brilliant suggestion. After comparing the nrv spring of the 510 to my marine stove, the diameters of the wires do appear quite similar. So, I'll be following the tek provided in the link Kero indicated above. Should this not work, I think I'll get a Coleman fuel tank and attempt to frankie it. But I have been wanting to get a 1 gallon chemical sprayer tank regardless of whether or not the original pump/tank works because I have been wanting a larger fuel reserve. Alcohol burns up really fast.
Well, alcohol does contain water so over the years, the spring must have rusted. I guess that is one disadvantage of having a spring on the NRV of an alcohol stove. Ron
Well, Thanks you Stu for offering. However, I have already made an order for brass spring wire. Not being patient to wait for the wire though, I took the spring out of a pen and bent it so that it would fit the nrv pip carrier. The pen spring is way too stiff to use for long term but... I pumped up the tank to 10 psi yesterday, sans fuel in the tank of course, and it held pressure for the past 24 hours all while using the same nrv pip. This tells me that my suspicions may be correct that the nrv spring has become weakened over time or wasn't the correct one to begin with and that the problem is not from a damaged seal. Whew...
Ok, I got the .016 brass spring wire in and well... It leaks pressure much more slowly than the original spring now does. The way-too-stiff doesn't let any leakage. So, a thicker wire than .016 inch seems to be called for. Actually, I have an Indian dilruba and a set of wire for it to replace its strings. I have .018 and .022 hardened bronze wire to replace the shuddh Sa and Pa strings. My question, before I go and buy more wire, is will bronze work? Will bronze hold up to being immersed in alcohol? Also, since the .016 is too weak for this stove's nrv, how much thicker should it be? Will .018 do in brass spring wire or will I need to go up to .020, .022 or .024 or beyond? What do y'all think? I really dont want to waste material and money experimenting but I have little knowledge and exerience of the physics of springs. BTW: the .016 brass spring wire worked like a charm for my Optimus 510's nrv.
I wonder if brass wound guitar strings would work? It's a stainless steel core wrapped/wound in brass or nickle, depending on which you get.
I went through my box of pens and found a not-so-stiff pen spring. Installed it, pumped up the tank to 10 psi and let sit for 48 hrs. Pumping was easy enough and the tank held pressure for the 48 hr test. Fueled up the stove last night and test run it. No leakage. So, up and working again. Thanks all. The coil diameter of this pen spring isnt wide enough so I do not consider this to be a permanent fix. Im really thinking about trying .020 inch brass spring wire. That might be stiff enough considering the challenge this nrv has given me over the years. I'd rather have to put some extra muscle into pumping the tank than risk fuel leaking out the nrv (again). BTW: the bronze instrument wire I had was too maleable and not springy enough to use but it gave me an idea of what .018 brass spring wire might feel like.
I am absolutely at my wits end on this nrv. Ive gotten .16, .18, and .20 inch dia brass spring wire from the same source as exeter_yak had used in the link provided by kero above. As I mentioned above, I found the .16 to not work. The ball point pen spring worked for awhile but no longer works? I really have no idea why it won't work anymore. I tried the .18 brass spring wire but it is too thick for the clearance between the post of the nrv pip bucket that the spring fits over and the inner wall of the nrv "assembly". So, its worthless to even try the .20 spring wire. I really just do not know what to do at this point. Pitching it is quite tempting. This brings me back to the notion of spending the bucks on a chemical sprayer to frankie. The nrv in that ought to work, yes? Otherwise, know of any good catapults? I might try grinding down the post on the nrv pip carrier to allow for room for the extra thickness of the .18 spring wire. Edited to add: The .16 brass spring wire eventually failed my Optimus 510 also but the .18 seems to be working quite well. For now at least...
Are you sure its the spring failing & not the rubber sealing pip inside the NRV try changing this before you go mad on the spring sealing problem Stu
I have some 0.020" stainless steel wire if you want to give that a go ? It will certainly hold up to the fuel !
