Had an embarrassment with my '24 No.0 Burner Primus 96 "User", it became incontinent on my last lunch break with a persistent dribble out of the pump tube I stripped it down and went to remove the NRV... Hello, that's tight I thought... I then realised I hadn't actually removed it before, it was functional when I gave it a going-over back in approximately 2014 and thought no more about it. My usual trick of clamping the NRV tool in the bench vice and turning the tank failed me, it sheared the head off the NRV, utterly stuck! I have one of the Korean NRV extractor tools, bought on a whim, and thought I'd try it. It's basic premise is a nicely machined T-Handle, with a sliding adaptor to suit small and large pump tubes (the same as the NRV tool he produces), but sized to accommodate 1/4" Hex tools and retained by grub screws. He supplied it with a set of cone-style screw extractors. The double-ended type where one end is a drill bit sized to suit the conical extractor bit on the other end. Now try as I might, these steep conical bits may be suitable for steel, but for brass, not a chance, utterly hopeless, they make a nice countersink though So, Plan B... Sized for 1/4" Hex bits you say? Right, a rummage in the toolbag produced Hex Drive adjustable HSS countersink drill bits. Stick-out adjusted to about 1/2" to 5/8" so they didn't protrude too far into the NRV. These effortlessly hand-bored out the centre of the NRV head to a "decent" size. After a further rummage in my spare easy-out stud extractor assortment, I found one with a long taper that fitted snugly in the T-Handle. A couple of flats filed for the grub screws to bite into and it was rigidly held/central I got it to bite tightly into the NRV and filled the tank with just-boiled water to give it a warm through, drained it off and held it tightly with a towel and went for it, something was going to give regardless... The NRV released with a loud crack! Sometimes you just get lucky Every successful stud extraction is a momentous victory in my book Hex Drive Countersink Drill Bits Easy-Out rummage tin Nice long taper easy-out fitted into T-Handle Fresh NRV installed, I also fitted a fresh burner washer as the original was mushroomed out. I gave the pump tube a hone with some extra fine Scotchbrite and Autosol to remove a couple of inadvertent scuffs I made trying to use the conical extractor. Pumped up, dunk tested fine Boiled a kettle to prove it was behaving again Looks like the trowelled-on solder has survived removal yet again.... The old NRV had a cork pip, so theres every chance it may have been the original 102 years use isn't shabby is it? 12 years use with me so far Cheers, Alec. @igh371
Sheared the head off the NRV, impressive; just as well you didn't cave in the tank side at the same time too () Impressive determination and ingenuity in nevertheless achieving success in the end though. You certainly threw everything at it
I grabbed an old file handle and a length of M6 stud, fully expecting to have to remove the pump tube.... Alec.
@Rangie Thank you for your informative stuck-NRV experience description! My recent pump-tube removal experiences might be mitigated in the future…
I've had that same feel when you use an extractor and you get the nrv out. I never felt happier. Great job man
@Rangie Since you know that the trowelled on solder on the pump tube is up to the job you can be more confident that the stuff around the riser port isn't going to give up any time soon either. Regards John
@Jeopardy you should see its backside! Definitely an old case of Defence in Depth (or thickness anyway) Cheers, Alec
Thanks for posting your nerve-wracking fettle @Rangie I referred to it today while trying to remove a stuck NRV from a Primus 41 tank. The edges of the NRV had slipped away from the tool too many times and had become too slanted to gain purchase. An extractor was the only way forward. The extractor bit had a square end that fortunately was the same size as a spindle. I was able to turn the extractor with an unusual combination of tools, including a reproduction 111T multikey with the knob removed, by putting them into a vise and turning the tank over it. I too heard the satisfying (slightly terrifying) crack when it finally released. I will have to get myself one of those nice Korean NRV tools.
