Testing NRV before installing

Discussion in 'Stove Forum' started by hikerduane, Jan 15, 2021.

  1. hikerduane

    hikerduane Subscriber

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    Only way I can see to test a new pip in a NRV is to suck on the head to see if I can create a vacuum. Thinking yesterday that maybe I couldn't get my lips to make a complete seal, but soon found out that was a indicator of the pip not making a seal, either from too hard, hanging up or weak spring. :( I tried this on some near worthless, aftermarket new ones I got off the bay a few years back and was able to create a vacuum, so moved that pip and carrier to my original NRV. Do you do anything different? I know years back that I had to unsolder and resolder some pump tubes to finally find a combo that worked.
    Glad I have my new NRV tool, would have been unable to break loose 3 NRV's on some stoves this week without it, especially one this AM.
    Duane
     
  2. Gunner

    Gunner Subscriber

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    @hikerduane - is it possible to reverse the leather cup on the end of the pump spindle, so that when you pull it, it tries to pull air out of the tank?

    Pump.jpg

    You might have to file the corners off the nut, to stop them pushing the leather cup washer out so far it won't fit into the pump cylinder - but it might be worth a try.


    HTH, and best regards,
    Gunner
     
  3. Tony Press

    Tony Press Australia Subscriber

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    @Gunner

    That method won’t work on pumps that have tapered shafts to allow the air to pass on the pull stroke.

    Tony

    Edit: Also, @hikerduane was looking at techniques to test NRVs before installation.
     
  4. hikerduane

    hikerduane Subscriber

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    This last of 7 had a very slight NRV leak, so fix it until it breaks. I believe the force needed to break the NRV loose, tweeked the pump tube so now a little reheat after clean up to see if the solder will reflow. :(
    Duane
     
  5. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Why not testing after installation?
    Easy removal now that the nrv is easy to remove.
     
  6. hikerduane

    hikerduane Subscriber

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    Ken, testing would save transferring fuel and associated mess from leakage. Test once.
    Duane
     
  7. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Won't the pump push back if the nrv leaks?
    I do not have to fill it to test the nrv. I put a finger over the jet.
    Maybe I am missing something. :?:
     
  8. hikerduane

    hikerduane Subscriber

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    Ken, air pressure doesn't always push the pump shaft out, could be a slight leak, can always add water or denatured alcohol in the pump tube to check for bubbles, but I want to check the NRV before I get to that point. It would be quicker to check if a NRV is working without removing it numerous times. I have considerable experience with NRV's as most of my large 96 collection needs the pip changed, many are up to 100 years old or more. Maybe it's time I came up with a process.
    Duane
     
  9. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi @hikerduane .

    “Hi @Surveyor there are slight differences between the NRVs from different Manufacturers and stove types.
    Here are a couple of photos I have just taken of the NRV from a Military No.12 stove, so similar to yours.

    [​IMG][​IMG]
    Can you confirm that your NRV is assembled like this one?

    Another tip: once assembled you can always test pump function using a glass of water and watching where the bubbles come from.

    From this thread:

    No 2 Modified Stove the Fife Fettle


    If I wanted to to test my NRVs before using them :

    1. I have spare pump assemblies recovered from donor stoves.

    2. I would modify one of these to lock the piston onto the pump shaft so that it provides suction on the backstroke.

    3. Fit the NRV you wish to test to the pump tube in the normal way. Fit the pump assembly with the pump piston at the top of its stroke.

    4. Immerse the lower part of the pump tube in a glass of water and push the piston to the bottom of its stroke. You should see a steam of air bubbles come out of the NRV.

    5. Keeping the lower part of the pump immersed, attempt a backstroke by pulling on the pump knob.

    6. If you are able to get any movement check to see if there is any water in the pump chamber. If there is, either the NRV seating or its pip is leaking and allowing liquid to pass.

    Best Regards,
    Kerophile.
     
  10. hikerduane

    hikerduane Subscriber

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    @kerophile, thank you George, just trying to avoid installation with a leaking NRV. I could dismantle one of my repaired/parts 96 founts to make a test tube like you mention.
    Duane
     
  11. cottage hill bill

    cottage hill bill Subscriber

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    @hikerduane What about finding a piece of copper tubing with ID big enough to slide the Optimus pump into and a couple inches longer. Cap one end and solder a fitting to the other so you can attach the pump tube solidly enough to get a seal. The copper tube becomes a very small fount. Add a couple ounces water or DNA and a couple of pumps to pressurize and you're home free.
     
  12. hikerduane

    hikerduane Subscriber

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    Thinking in the grand scheme of things, not a big deal since my collecting has been scaled back, just need a couple more elusive 96's. I would need stoves with NRV issues arriving every week. Thank you guys for your ideas. My custom NRV tool sure was handy this week, needed it on 3 stoves.
    Duane
     
  13. ROBBO55

    ROBBO55 Subscriber

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    @hikerduane

    I have tested RNV's by sliding a length of plastic tube over the body of the NRV from the back. Submerge the NRV in water and blow down the tube. I soon see if there is a leak.
     
  14. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @ROBBO55 Clever. Beats the risk of choking if @hikerduane’s method of sucking it goes awry.

    John
     
  15. ROBBO55

    ROBBO55 Subscriber

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    @presscall

    Yes, or you have to wait a while to get the NRV back. :shock:
    I have sucked on NRV's and there always seems to be some Kero to leave a taste in the mouth :cry:
     
  16. Sedgman

    Sedgman Subscriber

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    In respect of new NRVs I never assume they work and so I unscrew them and check that the unit is complete and the pip is seated correctly. I have had one where it was on a 45 degree angle. I have also ratted some in the past and need to check it is not an 'empty' NRV. I then check the operation of the spring to see if the pip carrier binds in the tube as some have small burrs on the inside where the small side holes are. If it catches for any reason I use a smooth file and check the pip carrier. I might then use a small drill bit of the correct size to remove any internal burrs watching I don't damage the thread.

    If it is a second hand NRV being reused I install an oversize Viton pip (not width wise but length wise) and I find this helps a lot. I don't have a spare pump to test them so I have been interested in some of the ideas posted above. I never reverse the pip to use the other unworn end as the rubber or cork is usually rubbish by then.

    My further testing is with fuel in the fount before I light the stove or lamp.

    Iain
     
  17. Twoberth

    Twoberth United Kingdom Subscriber

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    This may cover it here.
     
  18. hikerduane

    hikerduane Subscriber

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    @ROBBO55, thank you for that idea, will give that a try. All I needed was ideas or how others may test if at all a NRV.
    Duane