Stoves & how to use them efficiently

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  1. Spiritburner

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    STOVES & HOW TO USE THEM EFFICIENTLY

    This 1953 article is from the Technical Handbook of Camping published by The Camping Club of Great Britain & Ireland. The language & tone is delightfully of it's time but it is answers many of the questions asked by newcomers to the hobby. I have also added a few illustrations.

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    FIRES are generally objected to by farmers, and even when not, use of a stove for cooking is much more convenient. No small degree of skill is needed in the preparation and management of a satisfactory cooking fire, and the knowledge and energy necessary for the collection of wood which burns well, is not possessed by all. A stove may, therefore, be regarded as a necessity for the general run of campers.


    Spirit Stoves – These burn methylated spirit and possess the distinct advantage of cleanliness and light weight. They are extravagant in consumption and methylated spirit is rather expensive and not always obtainable in out-of-the-way districts.

    1426435473-Meta.jpg

    A more modern type uses solid fuel known as "Meta" and where only the absolute minimum of cooking is required it has certain advantages. Actually, a special stove is not required for " Meta." Any small metal tray, such as the lid of a tobacco tin, may be used as the container for the fuel and all then needed is a support for the pan and protection from the wind.


    Paraffin or Petrol-Vapour Stoves have been widely adopted, and are made in comparatively light forms and emit intense heat. The paraffin burning models are most popular, but a model designed for petrol is preferred by many. Choice between the two is one to be made by the camper and a full description of each is given in this chapter. However, the small petrol stove is lighter than the smallest paraffin stove, cleaner in use and easier to start. Its flame may be regulated and, on occasion, a further advantage is the burner carries a quickly removable nipple, while the paraffin (No. 96) burner is one piece and must be replaced complete. On the other hand the petrol stove is not so stable on the ground as the other unless used (as primarily intended) in its container.

    In this country at any rate, paraffin is move conveniently obtained in small quantities than petrol and is frequently obtainable from farmers. Paraffin -Vapour Stoves have no wick; paraffin is forced up to the place where it is burnt by means of air pressure in the reservoir and on its way passes through heated tubes; when it emerges it is in the form of a gas or vapour. A stove of this type comprises, essentially a reservoir, a pump by which a pressure of air above the paraffin may be created, a tube leading from very near the bottom of the reservoir to the burner, and a burner which is so constructed that the paraffin is heated on its way to the outlet, and so that the vapour mingles with air before it is burnt, and produces an atmospheric flame. In addition, a valve is provided on the reservoir by which the air pressure may be reduced, and a "starting-cup" is fitted around the burner to hold methylated spirit, or a substitute therefore, which is burnt to heat up the burner initially, and so start vaporisation of the paraffin.

    Method of using – If the principles upon which the stove works, and its main features of construction, as outlined above, are thoroughly grasped, reasons for various operations when using the stove will be readily seen. As oil will flow through the burner as soon as necessary air pressure exists, and as it must be in vapour form before it is burnt, it will be appreciated the heating of the burner must be the first operation.

    Methylated spirit or " Meta " is placed in the starting-cup and lighted; a saucepan put on the stove, will assist the flame to heat the burner, which should be shielded from side draughts so that it will play around the burner and make it sufficiently hot to start the vaporisation when the paraffin is forced up through it. The spirit flame also heats the reservoir to some extent (and the air within it), and the consequent expansion of the air will, even without any pumping if the valve be closed down, force some of the paraffin up into the burner.

    For this reason the valve is best kept open when the methylated spirit is first lighted, as otherwise the oil may be forced into the burner before the burner is sufficiently hot to vaporise it.

    If this happens the paraffin will issue as a liquid, and burn in that condition with a yellow, smoky flame, and the heat generated by it will cause still more liquid paraffin-fin to emerge, so that in a few seconds a flame may be formed two or three feet high, constituting a source of danger to the tent, etc. If by inadvertence the valve is not open, as it should be, when the methylated spirit is first lighted, and this result occurs, the valve should be immediately opened to release pressure.



    Get Firmly Fixed

    It is advisable to get firmly fixed on one’s mind that the opening of the valve will always check any alarming symptom which the stove may develop. If the valve is kept open and the burner is being properly heated, a small whitish flame will usually be seen after a little while at the burner nipple. When this is seen, or just before the spirit is all burnt, if it does not appear, close the valve. If sufficient spirit has been put into the cup, the small flame should then form, if it has not previously done so. One or two short strokes with the pump should then be made, and the whitish flame will disappear, and the vapour will burn gently at the burner head with the proper atmospheric flame. This flame should itself become more intense; if it does not, another stroke or two at the pump will keep it alive, and, when it has run for half a minute or more, further pumping may be effected to increase the flame as desired.

    Care should always be taken, however, not to pump up to the full pressure required too quickly, as, if the burner has not attained the proper temperature, the oil may be forced up so rapidly that it cannot all be vaporised, but emerges as a liquid, with results as above described. If insufficient spirit has been used (a somewhat rare fault in a beginner), or the spirit flame has not been sufficiently guarded, the spirit may burn entirely away before the small whitish flame is seen. In this event there is no other course but to put more spirit into the cup, after pouring out any paraffin that may have got into it – to see that the valve is open, and to light up again. Needless to say, one must be sure that all flame has ceased at the stave before the spirit-can is brought to it, or else the whole can-full may become lighted.

    It will be obvious that the intensity of the flame depends upon the air pressure in the reservoir; if a fiercer flame is desired it can be produced by further pumping. If a more moderate flame is needed, the valve must be opened until the desired flame is obtained, and then closed again. To extinguish, open the valve and leave open. The reservoir must not be filled completely, or even to such an extent that oil will come out of the valve if it be opened when the stove is in use. If this does happen, it is likely to light and produce a dangerous flame at the valve, difficult to extinguish without burning one’s fingers. Since the air space in the reservoir increases as the volume of oil decreases, more strokes of the pump will be necessary to produce a flame of a particular size, when the stove has been used for a couple of hours, than when first commenced.

    If the oil becomes so low in the reservoir that the air can escape up the tube to the burner, the flame will go out. Before it does so, the roar of the flame (in the case of a " roarer " burner) is usually interrupted two or three times, and then air with unburnt vapour issues from the stove and pollutes the atmosphere. Under these circumstances it is of no use to re-light the burner; open the valve, and then again fill the reservoir, and light up as usual.


    1426435563-96.gif
    Primus No:96L

    The "Primus" type of stove is made in many sizes, but those in common use by campers are:

    No. 96. Capacity, half a pint. Favoured by Pedestrian and Cycle Campers.

    No. 210. Capacity, one pint. Most useful stove if the extra weight is no objection.

    No. 221. Capacity, nearly two pints. The fact that it weighs considerably more than either of the two mentioned above eliminates its camping use, except for fixed campers.

    Burners.– The mode of operation of the stove is the same what-ever type of burner is fitted. Burners are, however, constructed in three patterns, two of them – the "roarer" and the "silent" – being interchangeable and capable of use on any stove from the pint size upwards. The third, the " 96," supplied with the half-pint "Primus" stove of that number is capable of use only on that stove. In both "roarer " and " silent " burners, paraffin passes up branching tubes to a burner head, and then down through two other tubes to a nipple, having a small orifice, from which it emerges. The nipple is in each case screwed and so removable.



    Pleasant Sound

    The "roarer" is more suitable for use in the open air, as the vapour is burnt at the pressure at which it leaves the nipple, and the flame consequently little disturbed by wind. Its roar (whence its name) interferes somewhat with conversation, but becomes in time a pleasant sound in the camper’s ears. Owing to construction, its nipple is only removable with the aid of a key having a universal joint, the use of which is such an awkward operation that, if care is not exercised, it will result in stripping the screw thread on the nipple, or on the burner itself, thus rendering the whole burner useless.

    In the "silent" burner, roar is eliminated by causing the mixture of vapour and air to pass through a baffle chamber at the burner head before it is burnt. In this chamber the pressure becomes reduced, and the flame is consequently less fierce and more susceptible to draughts than that of a "roarer." The burner can, however, be nicely graduated for simmering and other delicate cooking operations, and its nipple is replaceable with comparative ease, as by removing the baffles it can be got at with a key having a rigid handle. This type, however, requires more spirit for starting than the "roarer."

    The "96" (tube) burner differs in construction from "roarer" and "silent" patterns in that it has no branching tubes connected with a burner head. Oil passes up a straight stem having a nipple orifice at the top, and the stem is heated to cause vaporisation, both by conduction and radiation from a loose spreader-plate carried above it. No removable nipple is fitted, and if by mischance a pricker is broken in the orifice, the burner is hors de combat until a new stem can be obtained.

    Click on burner images for more details

    1426435643-Roarer.gif 1426435717-Silent.gif 1426435786-Tube.gif


    Prickers – These consist of a short piece of wire mounted in a tin handle, and are used for clearing the nipple orifice from deposit left by the paraffin. The nipple should be pricked out when first using the stove at a camp, but pricking is not generally again necessary for two or three days. If a badly-formed or poor flame is given at any time, the pricker should, of course, be used, but it should never be used unnecessarily, as the nipple orifice is unduly enlarged by so doing, and the efficiency of the burner is reduced.

    Assembling – Instructions as regards assembling are usually supplied with stoves, and it is only necessary here to remind campers that, as the stove will not work satisfactorily if there is any leak from the reservoir, care must be taken to screw down the burner, the filling-hole cap, etc., quite tightly. When the stove has been carried to camp with paraffin in the reservoir, and assembling is commenced, the valve should first be opened and then the cap on the burner tube unscrewed.



    Sooty Reminder
    Starting, Alternative Methods – Although methylated spirit or " Meta " is most commonly used for starting a stove, other methods are available. If the spirit has been " left behind " when packing, paraffin can be used for the purpose. Extra trouble and the sootiness of the procedure, will help to impress this item on the mind when packing next time! First close the valve – then give two or three short strokes of the pump to force about a dozen drops of oil through the nipple into the cup, then open the valve again. The paraffin should now be lighted, and the usual procedure adopted. If difficulty is found lighting the paraffin, two or three short pieces of straw, or wood chips, string, or the like should be put into the cup to act as wicks.



    Prevention Better


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    Temporary Choking – If dirt has been allowed to get into the stove or burner, it may cause a temporary choking by getting into the nipple orifice. This can be dislodged by the use of a pricker, but the cure is generally short lived. A permanent cure is effected by removing the nipple from the burner and blowing out the dirt, and by washing out the reservoir. Half fill the reservoir with paraffin, shake well and empty quickly. It is as well to wash out the reservoir regularly every month or two when in use, to use a strainer when filling the stove, and to keep the burner well protected from dirt when it is off the reservoir. A piece of fine wire gauze may also be placed in the burner just above the spirit-cup to assist in keeping the nipple free from dirt. Never remove the nipple of the burner unless absolutely necessary, as the screw threads are very easily stripped.

    Fuel Consumption – It should be noted that a stove burning at full pressure will burn about a pint of oil in three hours, and it is highly desirable to make sure that there is sufficient oil left in the reservoir before commencing a long cooking operation. Apart from interruption of cooking, if the stove runs dry before it is finished, the messiness and discomfort of handling paraffin and a hot stove are to be avoided, if possible, when a meal is actually under way.

    Leaky Washers, etc – It cannot be expected that a stove will work well if it is not kept clean and looked after. If air pressure cannot be maintained when the stove is in use, find out whether the burner is screwed on tightly, and whether valve and cap for the filling-hole are completely closed. If the fault is at the burner, paraffin may be seen creeping from the base of it over the reservoir, or coming off as vapour. If, in spite of screwing down the burner tightly, this still happens, a new lead washer is needed at the bottom of the burner.

    If any vapour is seen coming from about the spirit-cup, a new asbestos washer is needed at the joint above or below it. The washer should be damped before being inserted, and is sometimes made up with asbestos string. If the trouble is not at the burner, it is probably at the filling-cap or valve, and a new leather washer will be needed at one or each of them.

    If paraffin comes out of the pump as the piston is worked, or the piston is pushed out when released, attention to the pump valve is necessary. This valve projects from the inner end of the pump cylinder, and can be removed through it by means of a special key (obtainable from stove dealers) when the piston has been removed. Dirt may have got into the valve, or a new piece of cork may be needed in it. If it is quite impossible to get more than a feeble pressure in the reservoir, it is likely that a new pump-cup is needed. This can be determined by examining it.


    1426435925-Pump.gif
    Pump Assembly



    1426435966-Valve.gif
    Pump Valve

    Baffle Plate of the 96 "Primus." Should this be lost in camp, an effective substitute can readily be made by cutting a piece of tin with four projecting pieces to grip the top of the burner.

    Repair Outfits are sold containing washers for replacing as above, one or two extra nipples, a nipple key, and a packet of prickers. The various items can also be bought separately, and the washers may be readily made at home from the appropriate materials.


    1426436030-Spares.jpg

    Primus Spare Part Outfit


    Spirit-Cans – If methylated spirit is used for lighting the stove a can or flask is required to carry it. A quarter of a pint is usually sufficient to last a week, and aluminium flasks of this capacity can be bought. A cycle oil-can, or a metal-polish bottle with a screw-cap, can also be used for the purpose. Cans which deliver only the quantity of spirit required for heating up the burner each time the spirit is poured from them are obtainable. The " Meta " fuel previously referred to, however, is frequently used in preference to methylated spirit. It is light, does not evaporate, and sufficient for a week’s camping is easily carried in a match-box.

    1426436183-SpiritCan1.gif 1426436198-OilCan1.gif

    Paraffin-Cans – A can for an extra supply of paraffin is desirable, if the tent is pitched for two or three days on one spot, as it saves the trouble of dismantling the stove when it is necessary to buy more oil. The can may be fitted with a cycle-clip for attaching to the frame of the bicycle.

    Wind-Screens are usually made from a strip of lawn about 1 yd. long and 15in. wide. Four umbrella ribs shortened to about 18in. long are used to support the material. Hems at the end of the material, and tucks at equal intervals along its length, are made for the reception of the ribs, and the material is also sewn to the eye at the end of each rib. The umbrella ribs are stuck into the ground, when the screen is in use, so that the stove is protected from draught on three sides. A pocket about 4in. deep and 2in. wide sewn near the top of one of the end divisions of the screen, will be found useful for holding a pricker.

    Burner-Shields – A lawn wind-screen often does not sufficiently protect the methylated spirit flame when the burner is being heated up on a windy day. It can generally be shielded by the hands under such circumstances, but metal shields are obtainable which closely surround the burner, and are made in parts hinged together so that the shield may be easily placed in position. A suitable shield may be made from a piece of sheet tin, thin enough to be spread flat for packing or curved to act as a shield. An old cocoa-tin with the bottom removed, and cut along the seam, is often used. The bottom of the shield should be Vandyked, or some other provision made for the necessary supply of air.


    1426436337-Shield-71.gif

    The "Primus" Petrol Stove – This stove, known as the "Primus" No. 71/L, is designed mainly for use of motor-cyclists and others who have a ready supply of petrol available, but it has certain advantages which may commend it to others who wish to reduce weight as much as possible. It is smaller and lighter than the No. 96 stove previously described, and is intended for use in a metal container which has two cross-pieces secured across the top, on which to place the cooking utensils. The 71/L works on the same principle as the paraffin burning stoves, except that it requires no pumping. It is claimed also that it requires nothing more than a lighted match held near the burner tube or the warmth of the hand on the reservoir for starting, but in practice it is more satisfactory to use one or two tiny pieces of "Meta" in the cup provided.

    Used with the container, it requires no further protection from the wind, but some containers have eight sharp corners which are likely to damage other items of kit and some members prefer to dispense with the box altogether and use a fabric windscreen instead. In this case supports for the sauce-pan are necessary and may be provided by soldering lugs on the reservoir to take iron or aluminium legs similar to those on the paraffin "Primus." It will also be necessary to screen the reservoir from the heat of the burner by a circular piece of asbestos or other suitable material.

    A valuable feature of this stove is that the heat of its flame may be regulated at will. An adjustable valve is fitted in the burner tube which admits petrol to the jet as required, and this is used to turn off the stove when cooking is finished.


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    "Primus" stove, Windscreen, Canteen & Toaster

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    Reproduced with kind permission of the Camping & Caravanning Club of Great Britain
    from the 1953 book "Technical Handbook of Camping"
    & courtesy of Mick Emm​
     
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