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British military No.6

Discussion in 'Military' started by presscall, Aug 9, 2016.

  1. presscall

    presscall United Kingdom Subscriber

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    Pump petrol had been used in this stove judging by the smell and the burner was caked in soot from priming on the petrol. The tank filler cap seal was mushy from the petrol and I installed a replacement. A thorough clean and flush through and firing with Aspen and priming with alcohol put things right.

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    The burner is a type I'd got to know intimately before [getting rid of the infernal black spot] seen on a Military No.2 (Modified). I hoped the use of pump petrol hadn't unduly coked up the inside, but a test firing would reveal if it had. I was reassured that I have an unused burner of the type to substitute for it, since I didn't much fancy dissecting and reassembling another at the moment. In fact, it fired up very well.

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    The mounting to the riser pipe from the fuel tank is a simple BSP plumbing compression fitting with an 'olive' creating the seal.

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    That application of stock fittings extended to the control key, an adaptation of a 'Melco' brand box spanner (wrench).

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    Fiddliest job was replacing the fuel cap tank washer, which required easing the anchoring chain stay out of the filler hole.

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    Welded stainless steel construction, windshield and fuel tank.

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    The printed wording on the instructions decal gets mauled by the control key dangling down over the left-hand panel and that on the right, out of reach of the key, reads more legibly.

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    Good strong feet.

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    Folded up for stowage in the aluminium drum case.

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    Priming on alcohol.

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    It got going easily and powerfully. The burner flame is silent and steady but the vapourisation of the fuel is audible, a regular 'chuffing' sound.

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    Brew time.

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    Simmer's good and max too.

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    In this application of the burner after firing there's no sooty 'black spot' on the burner cap, unlike on the Military No.2 and the cap is left clean with just some heat discolouration. I reckon that's down to the inherent overfuelling in the pump-pressurised application and the self-pressurisation of the No.6 creates the right fuel/air mixture.

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    Now, two must-read posts from the late Steve Williams (Shed-Man, God bless him) relating his woeful experience of No.6 stoves on expedition in the Arctic. HERE and HERE.

    So far so good with mine, but maybe the arduous cycle of use on that expedition - although even then they seemed to fail very quickly - is what did for them. Steve wasn't precise in his description of burner failures. I wonder if in each or a majority of cases that rather makeshift burner-to-tank plumbing fitting loosened in use and caused incontinence and a fireball?

    John
     
  2. kerry460

    kerry460 Australia Subscriber

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    i like it a lot

    kerry
     
  3. pau-i-amor

    pau-i-amor Spain Subscriber

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    Nice stove!
     
  4. z1ulike

    z1ulike United States Subscriber

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    That's a beautiful flame and so nicely presented. I really appreciate the time and effort you put into your stoves and your posts. Thanks.

    Ben
     
  5. teckguy_58

    teckguy_58 United States Subscriber

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    Hi John,

    As always you seam to find the interesting stoves to present. Great looking stove and some very fine flame shots.
    Thanks for sharing.

    Cheers,
    Norman
     
  6. Rickybob United Kingdom

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    interesting way to construct a tank, but it looks a bit costly - military spec - made on a cost plus basis perhaps?
     
  7. shagratork

    shagratork United Kingdom Moderator Subscriber

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    Stunning and professional as always. :clap:
     
  8. presscall

    presscall United Kingdom Subscriber

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    Thanks all!

    In his post in THIS thread, Steve Williams wrote,
    I'm not convinced it was other than the securing nut and olive springing a leak. The 'vapourising tubes' Steve's referring to are two vertical heavy-gauge pipes and they're pretty robust. Steve himself said in his contemporary account that during the expedition temperatures were not extreme and were well within the parameters the stove had been designed for.

    The burner was in fact already tried and tested in the No.2 MkII Modified and apart from running rich is pretty much bomb proof in that stove, so why not in the No.6?

    I believe the answer lies in the proneness of the plumbing connector to allow the burner to twist when the regulating key is inserted, especially if roughly, loosening the connector and leading to a fuel leak, catastrophic if fired up at the time.

    In the No.2 MkII the regulating key is retained in position by the access hole it passes through in the case, so there's no twisting force on the burner coupling.

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    On the No.6 the regulating key has freedom to move sideways, tending to loosen the connector after frequent use.

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    Ensuring the connector nut is tight and taking care when inserting and using the regulating key is a crucial maintenance/safety requirement. It would have been advisable for the manufacturer to use a thread locking compound in the No.6 application. Steve and his party couldn't have been expected to anticipate that design flaw and take steps to compensate for it by frequent checks of the tightness of the plumbing fitting nut. As a plumbing fitting it wouldn't have been subjected to a twisting force. In the No.6 it is.

    A few concluding details to round off.

    Firstly, the distinctive projection on the fuel cap. It's not a safety release valve and serves no purpose I can think of. I wondered whether it might be to 'park' the regulating key, but it doesn't fit.

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    Another detail, the neat way the folding-out feet stow against the rounded tank base.

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    A number of firings have dislodged any residues of soot inside the burner as a result of burning pump petrol and it now burns beautifully blue throughout the simmer-to-max range.

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    In conclusion, a word about the birth of a legend associated with this type of stove.
    By 'legend' I don't mean David, but the reputation that a No.6 (true, I can only speak for my example) makes a racket such as he describes. It doesn't, but just a moderate percolating sound.

    John
     
  9. Rangie

    Rangie Subscriber

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    I think one of mine has a feature incorporated into the filler cap, I'll check.....

    Surging - check
    Banging - check
    Gurgling - check.

    It's a feature........ ;)

    Alec.
     
  10. Wim

    Wim Belgium Subscriber

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    It's alive!!!:lol:;)8)
     
  11. presscall

    presscall United Kingdom Subscriber

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    @Rangie
    Yes please Alec.
    You say "... one of mine" so that makes you experienced in using them. Have you had one or more fail, as Steve (Shed-Man) reported? Would you agree the pipe fitting connector is the probable cause rather than a brazing failure at a burner joint?

    John
     
  12. Rangie

    Rangie Subscriber

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    I have a couple John @presscall , one has a semi-choked burner and the other is the usual belching nonsense.
    They are good stoves, let down by:
    • Use of that damned No.2 Mk2 Modified burner, otherwise known as the clog-o-matic.
    • No SRV system to speak of.
    • The Wade coupling for the burner connection, although an industry standard UNF pipe fitting was not the best choice of fitting. They are really designed to be torqued once and left in peace. We have bits of kit which use these Wade fittings which have to be cut off and remade every few years (during or after an annual maintenance). If they had used even a carbon steel BSP Tapered fitting then it would have been sturdier and less likely to move/fracture.
    Had a look at mine, I thought one either had a SRV or was drilled for a retention chain but no. It looks a rather unfinished design to be honest. Not sure how many were produced but it may have just been one large batch for evaluation purposes.
    That said, the labels on mine are different which may suggest different batches.

    I only have the one tin between the two (which I used for my M1950 for a little while).

    If only they had used a different burner (roarer possibly), it would have been a better stove. There's no denying that there isn't plenty of heat conduction to get it up to temp/press but the reliability issues associated with that burner turns it into a bit of a liability.

    Army No.6, if it was an adjustable roarer, SRV, big burner to keep the tank hot and they would have had a good rival to the M1950 ](*,)
    M1950, if only they equipped it with a regulated burner, then it would be a rival to the Army No.6 :whistle:

    A great pair of quirky stoves but unfortunately for me, even with my love of British Army Stoves, I would reach for the US tin and risk it by turning it off and depressurising to adjust the flame.... :(

    Alec.
     
  13. presscall

    presscall United Kingdom Subscriber

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    @Rangie
    I'm grateful for your reply, Alec.

    Very informative and your comments about the coupling supports my hypothesis that it was most likely that that caused the failure of most of the ones used by Steve Williams and his colleagues during their expedition.

    So far so good with mine, but early days.

    John
     

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