Primus 340 sp, AI (1944), brass

Discussion in 'Primus No:340' started by SMolson, Oct 24, 2013.

  1. SMolson

    SMolson Subscriber

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    A brass Primus 340 sp, coded AI for 1944. These made their appearance during WW2 and ran for at least a few years post-war. The burner is No 3025 designed to run alcohol due in part to the availability issues of kerosene and petrol (coleman fuel). Besides the instructions and original box she appears to be complete. As a 'bonus' this one came with a Svea No. 774 brass windshield (shown as deployed).

    She doesn't show any verdigris, just a few scratches and has a decent patina so I do not think at this point I'll be polishing her up. I'm a user and she's a user so...

    1382640726-IMG_5647_Primus_340_sp_opt.jpg

    Reference material (from CCS) identifies this model (upper left).
    1382641710-1314820056-005_opt.jpg

    1382640796-IMG_5533_Primus_340_sp_opt.jpg

    Alcohol burner with single vaporizer tube, internal needle and spindle (non-jointed), green bakelight PRIMUS SWEDEN labeled wheeled handle. Steel tin with the little arm clasp to keep the top lid up (presumably to act as windshield with the stove inside of it, as shown in reference and my stove shot from above).
    1382640739-IMG_5650_Primus_340_sp_opt.jpg

    The steel tin is in good condition and retains her original colors of olive-brown outside and off-grey/green inside. She still has her PRIMUS label sticker on front top and PRIMUS SWEDEN face plate with wire loop handle front side.
    1382641622-IMG_5634_Primus_340_sp_opt.jpg

    1382640774-IMG_5549_Primus_340_sp_opt.jpg

    Burner has waffled priming material (asbestos?) encircling and tight to tube above the spirit dish, has long angled pilot light with large 'clasp' to support the thick single-tube vaporizer. Bottom of burner has lead washer.
    1382640819-IMG_5554_Primus_340_sp_opt.jpg

    Svea 'MADE IN SWEDEN' and 'SVEA No. 774' 2-piece brass draughtshield. Not original to the kit obviously but she fits the burner fine.
    1382640845-IMG_5640_Primus_340_sp_opt.jpg

    Internal needle protrudes from jet when turned off much like burner 4155 (spindle all the way CW). No stamping on burner.
    1382640805-IMG_5535_Primus_340_sp_opt.jpg

    Outer steel cap labeled PRIMUS METAL SWEDEN No. 4205, 4 rolls of holes.
    1382640790-IMG_5525_Primus_340_sp_opt.jpg

    Inner cap with center tube rolled as it contains a seem lengthwise. Single-ended spanner labeled PRIMUS one side and SWEDEN the other.
    1382640839-IMG_5639_Primus_340_sp_opt.jpg

    Fuel tank a standard 210 and is stamped PRIMUS No. 210. An impact to the pump tube area has been soldered by previous owner. Pump rod and handle made of brass.
    1382640825-IMG_5555_Primus_340_sp_opt.jpg

    and MADE IN SWEDEN
    1382640831-IMG_5557_Primus_340_sp_opt.jpg

    Side with A/B B.A. HJORTH & Co, Stockholm Sweden. then the Primus trademark: Sole Makers of the Genuine APPARATUS in 4 languages.
    1382640812-IMG_5540_Primus_340_sp_opt.jpg

    Bottom stamping AI 8.
    1382640859-IMG_5644_Primus_340_sp_opt.jpg

    No writings on fuel cap, vent screw or center fount cap.
    Vent screw unscrews but is not removable from fuel cap, fine brass linked chain for 210's of this period. Leg sleeves each have small hole near their bottom to allow water drainage - again typical of this period of No. 210.
    1382640853-IMG_5643_Primus_340_sp_opt.jpg

    Previous user had threaded white-rubber gaskets (non heat resistant) over top of the hardened originals, which were removed during the checking/cleaning process. The original gaskets in both her fuel and center fount caps had dried out and were replaced, as was her NRV's original cork PIP. This one with a lead washer, making removal and replacement very easy. Her pump leather was dry but otherwise in fine shape, a dunking in sewing machine oil made her supple and usable. She passed all the pressure tests, so lit her up.

    Priming
    1382640871-IMG_1236_Primus_340_sp_opt.jpg

    Wave of flame enveloping the outer cap as she lights
    1382640877-IMG_1243_Primus_340_sp_opt.jpg

    Initial burn
    1382640884-IMG_1245_Primus_340_sp_opt.jpg

    Running consistently
    1382640890-IMG_1258_Primus_340_sp_opt.jpg

    A very nice stove but can be finicky to keep a consistent burn using 100% methyl hydrate. They have a tendency to exhibit a 'breathing' or 'pulsing' pattern to the flame at higher heat outputs, which can be controlled by reducing the heat. But once the flame is managed properly they are excellent stoves.
    The case she's packed in, like the Primus 41's, is solid and durable and fits her snuggly when packed. I would not recommend running her inside her case as shown in the picture: not efficient, too confining, scratch the inside case paint up to crap, limit pot size, etc. So either make a draughtshield or use a compatible equivalent from another stove.
     
    Last edited by a moderator: Jun 26, 2015
  2. Tony Press

    Tony Press Australia Subscriber

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    Now that's very interesting.

    I have a very similar stove: a Primus 210 tank and a 4204 silent burner (year, 1947). It came to me in an Optimus "picnic tin". I was about to post it in the Primus 210 Gallery. The 210 Gallery has only silent burner stoves.

    Should I post it in the 210 Gallery or elsewhere?

    Cheers

    Tony

    Ps Its pump tube is soldered in a similar manner.

    Pps I see that a 4204 silent burner on a 210 was used by Hilary on Everest:

    https://classiccampstoves.com/threads/15534
     
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  3. bem1965

    bem1965 Sweden Subscriber

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    Thank you so much for posting this!

    A beautiful stove and excellent photos (as usual).

    Stoves with these alcohol burners turn up now and then on the auction sites, but prices always way outside my budget....

    /Lars
     
  4. boknasild

    boknasild Subscriber

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    Thanks SMolson
    Beautiful stove and and an outstanding presentation. I have a Primus 341 that runs on alcohol and have noticed that it can sometimes "pulse". brgds Bjørn
     
  5. itchy

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    Nice stove and very nice presentation and description.
    I have Opt 45 with an alcohol burner that also does not like methanol so much. Surprises me a little since I would expect these were designed to be fed wood alcohol rather than grain alcohol.
     
  6. SMolson

    SMolson Subscriber

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    Hi Tony - In my opinion, if your stove with that burner was not marketed as a kit or sold together by Primus I would add it to the 210 Gallery. I assume you meant the other 210's were 'only' roarers, and not silents in that model section? I've seen 210's modded with various silent burners (mainly regulated ones) on them, but these may be piecemeal kits put together by users/buyers and not bought/marketed new by Primus back in the day (or perhaps just customized sets for special needs/requirements?). But you'd have to check all the Primus catalogues to see and hopefully others can chime in as well. Thanks for the link, fascinating history and account.

    Hi Lars,

    Thanks - this is from a private purchase, no auction and spent $40 Cdn for the kit. I have not seen this model come up on the conventional $$ auction sites so have no idea what they normally would go for. I like the provenance of her being designed/manufactured during WW2 and the economics of running on alcohol.

    Hi Bjørn - Thank you, the Primus 341 looks like a beautiful stove, maybe one day I'll be lucky to come across one of these yet, a nice user version. I have a few other alcohol burners on pressure stoves (all Optimus), and they too exhibit the same issues to some degree. The best (or most consistent) of them imo is the Optimus Hiker T with the proper jet/restrictor tube.

    Hey itchy - maybe they used or were designed to run a different type of alcohol back then compared to today's? I'm going to experiment with fuels and mix in some coleman fuel or kerosene to the alcohol to see if that helps stabilize the burn without producing much if any yellow flame (due to burner design and higher vap point for those other fuels). Going that route will help increase the heat output of the burn (shortning cook/boil times) but then negate the cost savings benefit (and other advantages) of using alcohol. There's also the risk of improper vaporization, mixing issues (layering), and safety.

    Edit: forgot to add that this now is the 3rd or 4th 340 sp in the Gallery section so perhaps she, like a number of other stove models found in the 'Other Model' sections, should have a dedicated group listing for their respective manufacturer?
     
  7. DAVE GIBSON

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    wonderful stove but the details like the drain holes in the leg sockets just floor me..these people thought of everything and if the cost for another move with a punch--well lets do it!
     
  8. SMolson

    SMolson Subscriber

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    I don't have every year's 210 nor have I searched through the gallery's listing of 210s to find/narrow down the date they added the holes, but it was somewhere between the late 30's and mid 1940's. It may have been applied to similar models of theirs as well that likewise don't use the pot supports or pot support sleeves as stove legs (e.g those with attached fixed or foldable 'feet'). But in theory it's nice addition. I have a few older 210's without the hole that have had the lower extent of their steel pot supports rusted. This arguably resulted as a consequence of sitting in sleeves with trapped water (from either rain or cook/kettle pots overflowing/dripping during cooking process).
     
  9. NP4-8-4

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    An interesting stove. Thanks for posting. I wonder what the market for Swedish made stoves may have been in 1944? Export? Military, based on the color of the tin and the retaining chain on the filler cap? Domestic sales?
     
  10. SMolson

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    Hi NP,

    Just an assumption, but I would suspect they were sold for domestic commercial use and for export, not military. I don't know how long after the war they were produced, but at least a few more years post 1945.

    The jet and 'burner bell' - 1383061140-IMG_5523_Primus_340_sp_jet_opt.jpg

    Using a mixture ratio of 250 ml methyl hydrate + 75 ml coleman fuel you achieve a consistent, blue flame that does not pulse, no yellow and runs at high to medium-low setting. At low setting the flame is inconsistent and risks extinguishing. I've cooked a number of meals on her now in combination with other stoves (brunch and dinners) and she works up to expectations. Have not attempted any deep frying (may not reach the heat required) and due to the issues simmering is not good with rice.

    edit: why would the chain have anything to do with thoughts it may be for military use? I have a Primus 41, 1941, with the same tin color as this 340 sp, and it too I believe was for commercial, non-military use.
     
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  11. Spiritburner

    Spiritburner Admin Subscriber

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    Great find. These were popular during this period due to the shortage of kero.

    The tin colour & chain are civilian market features.
     
  12. Dutch_Peter

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    Hi SMolsen

    I've had the same problem with this stove that it blows itself out when opening the fuel valve more than a little. I found that it needs less air in the fuel/air mixture. To do so one can use a restrictor or when no restrictor available, close 2 of the 4 air holes in the burner head with nut and bolt.
    This trick may work for your stove as well.

    Cheers,
    Peter
     
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  13. SMolson

    SMolson Subscriber

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    Hi Peter,

    Thanks for the tip. The inner cap's tube sits just above the jet when it's deployed. It functions much like the removable restrictor tubes (with the two small base holes) on the more standard burners with the 4 tubes required when used with alcohol and supporting jet (e.g. Optimus Hiker T). But even though this one's inner cap is a little larger than the standard kero one, she doesn't sit fully around the jet like the removable restrictor tubes, there remains a gap. SO I will try your suggestion when she needs to be refilled and I'll use 100% methyl hydrate and block 1/2 the holes with nut and bolt or equivalent.
     
  14. SMolson

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    Hi Peter - I refilled the stove with 100% Methyl Hydrate, so I tested your solution and covered 2 of the 4 air holes (opposite each other) with sized-to-match folded tin foil pieces. Resetting the inner and outer caps, primed and lit the stove and she ran very well - just a little breathing in the flame and very minor (15%?) tearing away from the burner in pulse-fashion. I removed the tin foil pieces, restarted it but the same problem again - flame would go out in short order. With the fuel 100% meth she doesn't burn as hot as the meth/coleman fuel mix I had used earlier, so longer cook times are necessary (~< 20%), but the flame is consistent and at 1/2 the cost more economical. SO perhaps it is a defect in the burner design (hard to believe given Primus track record), that or they used a different alcohol. Thanks again!
     
  15. Dutch_Peter

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    Hi Smolsen,

    Good to read that it's working !! Economical is a big plus imho because it means saving money for other important uses (buying more stoves (lamps) :D :D ).
    It does not burn as hot on alcohol as I discovered as well, when using the 535A on alcohol with 2 of the 4 air gaps closed. My theory is that alcohol has less energy per unit compared to paraffin or gasoline, which causes a lower heat output. Cooking in my garden on the 535A, it couldn't get a 10 Liter pan to boil in time, so switched to an Anho 100 (paraffin) for boiling and put it back on the 535A for simmering.
    Guess that your Primus 340 should come with a restrictor or as you say, it's a design error. That would explain why it's a rare piece :p (not many would buy it if the design turns out to be flawed imho).

    Cheers,
    Peter
     
  16. SMolson

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    Hi Peter,

    Check this chart for comparison of various fuel attributes:

    http://zenstoves.net/Fuels.htm#FuelComparisons

    Alcohol's energy per same volume is considerably less than both Kerosene and Coleman Fuel so cook times (and required fuel) will be increased accordingly to complete the same task. By mixing the meths with coleman fuel for an improved, more consistent and higher energy burn the economics suffer of course so you're back at square one. But the burner works well regardless, including a low enough sustained simmer to cook Basmati rice (25 minutes on simmer) properly with no burning/scorching.

    Often the fact a stove (or in this case burner) design is faulty (as in above with pure meths) doesn't reduce the desire for some collectors to seek it out so their sale prices and interest reflect it. I'm a user primarily, so I would not seek another of this burner design (despite the provenance around the reason for their development). My search continues for the (non-existent) 'perfect' stove(s).
     
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  17. Dutch_Peter

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    Hi SMolson,

    Thnx for this interesting link: http://zenstoves.net/Fuels.htm#FuelComparisons

    It shows once more that paraffin isn't just paraffin and gasoline isn't just gasoline; there are many differences and subspecies.

    Peter
     
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  18. SMolson

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    Thanks to another post on the subject, the alcohol these were designed to use for fuel was not methyl hydrate but methylated spirits (denatured alcohol or marine alcohol).
     
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  19. Tantra

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    I suggest use 95% alcohol
    Drills the nipple to 0.55mm