Primus No.4 - 1939 *

Discussion in 'Primus No:4' started by kerophile, Jun 12, 2007.

  1. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi, I thought it was time to have some more stove photos!

    Yesterday I worked on this Primus No.4 stove, dating from 1939 ( code AD). The Primus 4 is not a common stove and I am not sure if it was produced after WW2.

    It is a 1.5 pint, brass tank, paraffin stove with fixed legs. It was fitted with a small silent burner.

    Its sister stove is the Primus No. 0, which used the same roarer burner as the Primus 210.

    When I acquired this particular stove I soon got it working well. It was one of those rare paraffin stoves which would self-pressurise during the priming stage if the air-valve was closed.......However the burner was a roarer and therefore wrong.

    At the recent Newark CCS meet I purchased a partial Primus 4 silent burner. I had some "new" silent caps in my spares box, and knew I could now complete this stove.

    1296898895-DSCN0002_edited-22.jpg

    here are some photos of the stove operating. It has a brass outer silent cap, and I am using heat -proof washers made from Novus 30 material.

    DSCN0003_edited-30.jpg

    DSCN0004_edited-16.jpg

    The silent burner on a No. 4 stove has a particulrly deep "skirt", collecting heat for the vapourisation and providing a shroud for the actual silent burner cap.

    DSCN0006_edited-15.jpg


    1296898923-DSCN0007_edited-16.jpg

    This photo shows the five rows of holes in the small No.4 silent burner cap.



    1296898931-DSCN0008_edited-14.jpg

    This shot emphasises the depth of the skirt. It is much deeper in proportion than that on a "modern" Primus No. 5 silent burner.

    The stove works well and is both powerful and relatively quiet. Just the thing for an early-morning brew-up without disturbing Ian in the neighbouring tent!

    I still need to tidy up the soldering on one of the legs but the stove is going great and at 68 years ol age is a credit to its Manufacturer. Take a bow Primus !

    Best Regards,
    Kerophile.
     
    Last edited by a moderator: Jun 26, 2015
  2. johnsnz

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    Very Nice :D

    I wonder why they used that style of shroud on the burner?

    Cheers

    john
     
  3. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi John, I believe that as you go down in size with silent burners, it becomes progressively more difficult to get effective full vapourisation of the paraffin. You simply don't have sufficient surface area in the chamber at the base of the burner, under the silent caps.
    If a deep shroud is introduced this captures combustion heat from the flames and conducts it downwards to where the vapourisation needs to take place.
    That's my theory anyway.
    Best Regards,
    Kerophile.
     
  4. johnsnz

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    Hi Kerophile...

    That theory sounds good.

    How much smaller than a 2 pint Silent burner is this primus no 4 style?

    Also what's the advantage of brass SB caps over 'primus metal' ones just lifespan I guess
    (and their nice to polish ;) ;) )

    Cheers

    John
     
  5. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi John, I have just taken some shots of Primus 5 burner ( dated 1955), alongside a
    a Primus 4 burner ( dated 1938) , on the right, for a size comparison
    DSCN0006_edited-16.jpg

    DSCN0011_edited-9.jpg .

    I always find it difficult to judge the size of a stove from a photo, unless there is something of know dimensions next to it to give me an idea of scale.

    Both these burners are virgins, just waiting for the right, unattached, stove to come along.

    Best Regards,
    Kerophile.
     
  6. exeter_yak

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    Hi George,
    You have it running quite nicely. I think the deep dish shape of the older silent burners is a bit more attractive. It think it would pick up more radiant heat with the deeper shape, and I suspect the stove outfitted with one of those would work a little better in more adverse conditions than the later models of 2 pint silent biurners for example with the lesser sized and less dished outer ring on the burner.

    Good luck with the continuing work on the stove.

    Regards,
    Doug
     
  7. barrabruce

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    Thanks George
    Doubt if I'll be seeing one in my lot.
    Hmm I bet that glows red in the dark.
    Certainly some thermo heat feed back.
    Looks as if the inner cap would glow.
    Does this shorten the life of the caps any great sigficance?

    Trying to firgure out why most silent stove have knackered or "lost" burner caps.

    :D
    Nice I think that extra burner would look nice on a 1 pint collaspable.

    Barra
     
  8. spudz

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    Underburn ?

    'cause they fall off with ease once the retaining wire breaks ?
     
  9. Spiritburner

    Spiritburner Admin SotM Winner Subscriber

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    Glad you got your old '4' going George. These are nice burners! The 4 hung around for a little while after WWII but not for long!
     
  10. Brass monkey

    Brass monkey Subscriber

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    Hey all, been a while since I've been here...good to catch up on whats been going on recently

    I have here a pre 1911 No4, not in a great state missing legs, pump handle and burner caps. Does have the original burner i think...

    stove2019.jpg

    Maybe one day it will look as flash as yours
     
  11. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi, I have recently been doing some work to understand the different forms of the silent burner Primus used on their No.4 stoves.

    The tank of the stove featured in this thread dates from 1939:

    1315073559-St.247._Pr.4._1939-1.jpg


    However as pointed out in the introduction, the stove came to me with a roarer burner and I replaced this with a suitable No.4-type silent burner I acquired. This burner has the deep skirt characteristic of an earlier date and when I examined the burner more closely I find that it is marked RH, which would date the burner to 1927:
    1315073571-St.247.-Pr.4.-1939-2.jpg 1315073583-St.247.-Pr.4.-1939-3.jpg 1315073594-St.247.-Pr.4.-1939-4.jpg

    Best Regards,
    Kerophile.
     
    Last edited by a moderator: Jun 26, 2015