Document 3QEyQpbv4rEpd7DKX3ZByn1rD

0 p Y TO: Office of the Quartermaster General . Washington, D.C. FROM: W. C. Coleman, President The Coleman Lamp and Stove Company SUBJECT: New Fire Unit for Army Field Range The Army Range Fire Unit now in use is, in its general plan, of mesa excellent design. The Army Engineers, who conceived the adeas "chat nave entered into the complete construction of this range, did a good job. The general idea of the angle iron frame constructed to slide in and out of the range; the use of two tanks, one on either side as far away from the heat.of . the burner as possible; the general structure of the burner head and the funda mental idea of filtering the lead out of tetraethyl brands of gasoline by an asbestos filter disc still proves to be in my judgment the best way of performing this function. . The troubles which have developed in field use have been due to detail of design rather than to the general concept of the entire unit. No designer produces a perfect mechanical device t the first attempt. . It is to be expected that six years of field experience would reveal many change: that could be made 'which v.oulu overcome the troubles which have been experienced in field operation and thereby give better service in many ways. Ouch a design is what The Coleman Lamp and Stove Company has undertaken. We have had more th:u forty years experience in the field of gasoline pressure burners end we have broi to bear whatever of engineering talent and experience we possess to the accompli; ment of this task. In the early years of our experience in producing gasoline burning appliances, our favorite alibi for field troubles'was the phrase "not properly operated acco: ing to directions". Later we came to understand that this alibi is only a face saving device*, ffechanical appliances must work in spite of errors by the ooerat If the operator does something continually thaw he should not do, we design* the product so that they cannot. If there is something they should do for successful operation that they do not do, v;e maxe it so the product does it anyway. Good mechanical structure must anticipate human error and. prevent serious trouble and we believe there is no substitute for proven successful experience. Our approach to the redesign of the Fire Unit has been: 1. To gather from responsible sources a list cf the real troubles which hive developed in field use. . 2. To analyse the causes which have produced these troubles and 3 To reconstruct the unit so as to remove as far as possible the causes that have been responsible for the troubles experiences.  % 1J We are- attaching hereto a list of twenty- one specific troubles, vhich hove been reported; t o :us iri field operation arc. in the production of the. present Fire Unit. With this' list ;;e are Outlining the cause 3 which seem to be responsible and the construction l'eatures of the new u n i . na-t will remove these causes or reduce them to a minimum. This is a report of progress and in a few days we will he able to submit the completed unit to the proper officers in the Quartermaster Department at Washington W. C. Coleman:p Fnc. Sincerely yours, t u f c o l f ::'?! and stove company C. Coleman President 0003539 V -h FERE UNIT - FIELD TROUBLES Leaks from Asbestos Filter Chamber; Cause of troublet The Filter Chamber is closed by a ground joint 14" long at perimeter and held only by center bolt of small size. There is too much surface for bolt to hold tightly. Also the cap warps by heat, making tight joint impossible. . .. Rer.iec.ied in Hew Coleman Designed Fire Unit: The Asbestos Filter Chamber is made of two stamped steel disk-like plates welded together at edges and tested at factory for leaks. This completely eliminates above trouble. 2. Leaks at Air and. Fuel Line Connections. Attempts to tighten vdth large v.-rench often breaks connection from Generator Tube: Cause of trouble; The jam connection is improperly mads. Connecting sur faces at flat angle require excessive wrench pressure to tighten. These are disconnected daily for cleaning. Remedied in Few Fire Unit: An acute angle jam is used for Air and Fuel Lines which require less than l/5 the wrench pressure to make tight. Also they are factory assembled. The burner is so designed that no disconnecting of these joints is required in the field for cleaning parts. 3. Leaks from Generator Tubes due to excessive wear, caused br disassembling daily dor cleaning; Cause of trouble: Tally disassembling of threaded parts is always a hazard, especially when dona by untrained men. Crossed threads and stripped threads render, equipment useless and require expensive repairs. Remedied in New Fire Unit; The Generator Tube is eliminated. There is only a dry vapor tube to clean. Only a limited amount of carbon is deposited in tills tube. Cleaning out at long intervals instead of daily reduces the hazard Lt__ Filler Co o Leaks and Broken Tank ...Connection for S me; Cause of trouble: Dus to location, the filler cap is subjected to'excessive heat, which eliminates use of gasket. A metal to metal joint requires ex cessive wrench pressure to make tight. Bushings are often twisted from tanks by brute force and lack of mechanical judgment, ..hen leaks wt this cap cause tanks to lose pressure. Remedied in hew Fire Unit; The Filler Cap is located in end of Fuel Tank out of the excessive heat zone. Regular filler cap structure proved by .20 years use is employed. The cap is operated by hand, wrenches do not fit on same so excessive force, which is unnecessary, cannot be used. 5 Lighting Troubles, due to lack of skill in juggling two valves, one for fuel and one for air; O'nn 3 of trouble: Average operator is unable to secure correct mixture of air and fuel for rapid heading and often floods burner with too much fuel earning a bad flame over extended period. - ... ... } ^ 0 0 0 9 o 0 0 .rygf'da-ahdvfd'"'' G- , \ o * 'f-\o tieg AT* r- y^ \tu ^ xaedied in New Fire Unit:' One Falve operation with o\ * eyaixtur - Air and Atomized Liquid Gas. This lighting .used on small ''Military Stoves" and Gasoline Prs m a n y .operators are familiar. Lc Control oir live is the same as interns, with which 6. Lighting Troubles,: due to liquid fuel getting into Air Tank and then filling air lines at starting, causing the burner to flood with liquid fuel: Cause of trouble; In present structure this occurs because of the two-valve lighting device. When both valves are open, excess vapor pressure generated in fuel -.tank by heat may cause a reverse flow' from fuel tank to air tank. Then at starting liquid fuel flows through both valves and the burner is quickly flooded. - Remedied in New Fire Unit; In the new unit fuel and air are in both tanks. The pressures in both tanks are equalized at all times completely eliminating this lighting trouble. Air alvuys flows from torn of tanks above fuel level. 7. Lighting Troubles, due to flooded burner, caused by slow vaporization when starting same at low temperatures; Cause of trouble: At very low temperatures all atomising devices tend to-be .OTT in generating vapor which means slow starting, which, in turn, means excess 11.quid accumulation in the burner while heating up. Remedied in Hew Fire Unit: The new unit is equipped with, a handy "rain device" to effectively oispose of such accumulation of liquid without per ceptible effect on the bnrnqr operation. Lighting Troubles.- cue to I ick oi knowledge and lack of lancerst? main, correc-G me .hod oi operation; to Cauie of troubl e : . Thc seven pages of minute printed directions i.re often never seen by the ope rator. If seen, ere seldom read. - if read, are too often not understood. Operation and servicing requires too such specialised skill Remedied in New Fire Unit; In the New- Unit operation is greatly simplified, All essential directions are stated on one cage and the most vital operating directions are on the operating part ftself, the same as on Military Stoves and the standardised Gasoline Lantern. 9 Poor Flame Quality, due to misconception as to what kind of a flame is hottest and best suited to the range structure - which requires a long flame, green at slots, shading to blue and then to orange at the ton; Cause of trouble; The air adjustment is left entirely to operator's judgment, which cannot be relied uoon. The flame valve structure is like a water hose nozzle and tends to produce a variable spray of fuel through the bunser tube, sence, it is very difficult to maintain a consistent flame quality which must have a balanced mix of Air and Fuel. Remedied in New Fire Unit: Air Control is positive -and factory adjusted - positioni for lighting and one for oners.tion. The flame va l\re .ntaii:s a uniformly solid jet of ot sprayed) thus se cur: :imum buns en efficiency for HViX-C.he of air- to support combustion K 0009001 . ..._ 5 \, y ' Poor Flame Quality due to an enlarged Jet Or?.flee which produces nr. incorrect ' a, .xture of Air and Fuel: . & Cause of trouble: IThen closed this flame valve shuts elf at the orifice with a tapered .steel needle, which enlarges the orifice when too much force is applied. As valve cools the body of brass contracts much more than the tapered needle stem of stainless steel, thus forcing the orifice. . -: ' ` 'i ' Remedied in New Fire Units The New Flume Valve does not use a tapered needle but .a. straight cleaning pin closely fitting the orifice. No force exerted by operator, -or by variable metal contractions can effect ary enlargement of the orifice. 11 Removal'of Lead is not consistent - at tine excellent, at other times poor: Cause of Trouble: Careless operators fail to adequately clear, all sealing surfaces in the filter chamber in which ca.se the fuel by-passes the asbestos filter. This is indicated by lead deposits at burner slots. Remedied in New Firs Unit; The voided structure of the combined vaporiser and filter names possible a perfectly sealed filter so th t no fuel by-passes the filter in this replaceable unit. 12 Cleaning Troubles vt.es uwlna leveled ass. The Filter Chamber must be opened two times each dap, ell '.rants screwed and brushed and wiped off carefully. A new fliter is then nut in: CM CO CD CD O Oo XU l Cause of trouble; The job requires cooling cion the burner; the use of a big xronck. which .wy break off the retaining cap screw requiring expensive repairs. Clearing all parts well trices time. It must be well done or leaks occur when again assembled. Remedied in New Fire Unit: The new Replaceable T'elded Filter Disc which also vaporises the fuel eliminates all this cleaning and leak trouble. It requires less than a minute to replace sane, which operates several days with no care ov service. 1?. Clogging Troubles - The Generator Tube which deliver.-; fuel to the Filter Chamber Is ads ua raoi'dly. It requires disassembling and cleaning out daily: Cause of trouble: Tetraethyl lead is deposited in solid form in any vapor ising chamber. The Generator Tube vaporises much of the fuel before reaching the filter chamber. To remove the entire assembly for cleaning requires breaking six connections - a daily performance often resulting in leaks or breaks when same is reassembled. ' Remedied in New Fire Unit; The Generator Tube, is eliminated - .the .fuel is completely vaporised in the roplacer.tie disk-like chamber which also contains the asbestos filter. All these troubles tire completely eliminated. 1/. Cleaning Troubles, due to carbon and, yarns in the flame v ,lvo body nd orifice of' the jot; Cause of trouble; The major portions of who carbon and gum eur.;c from the . high tempera ware distillation fractions and crocking of the vr.por by excessive heat. This carbon is then solidified after the lead is filtered out. A con siderable- `portion is, therefore, carried directly into-..the, valve tody, causing :r --A 'lo . many operation troubles. Remedied in Hew Fire Unit: Much larger space is provided in the flame valve for this carbon so same needs cleaning less frequently. More important, hovjever, is the carbon filter screen in the Gas Tube ana Valve Assembly. ' which effectively filters out carbon and gum in the vapor. Since the free carbon and gum content is about l/lO that of lead, this second filter needs to be replaced only at long intervals of time. 15. Broken Parts Troubles (Very Serious) - now requiring expensive repair assem blies and delays which render continuous dependable operation difficult to obtain: Cause of trouble: The cause lies in mechanical design. The trouble points are - (1-) The ground joint of filter chamber cap. (2) The flat jamb connections of air and fuel lines. (3) The metal to metal filler cap joint required because located in excessive hot zone. These are disconnected daily and require a large wrench and much force to tighten. Remedied in I.'sn Fire Unit; (1) The Filter Chamber is of welded sheet metal construction and is replaceable, (Uo cleaning .it any time.) (2) Standard Fuel Line connections have tapered jambs which require only l/5 the wrench pressure. (3) The Filler Cap is located in a comparatively cool place and a standard hand operated cap is used. The small eight-inch wrench supplied is adequate for all servicing and is a safety factor against breakage. ouu of range a few inches onlv, while burner is still red hot. Spill a little fuel end everything is ablaze. (2) Leakv joints and Connections. Operators try to tighten same while unit is lighted and a break occurs. (3) A burner structure which if flooded, often spills fuel out by way of bunsen tube. (j) Tanks having... no safety blow-out may be exploded, by external heat: Cause c-f trouble; The Filler Cap is -in a dangerous location. The daily disassembling for cleaning causes fuel and air leaks to develop. At low temperatures the burner at starting is almost sure to be flooded. This will happen e.t any time if the two valves controlling air and fuel are not properly manipulated in starting. All gasoline pressure tanks with no safety blow-out in case of too much external heat are considered unsafe. Remedied in New Fire Unit: (1) The filler cap located in end of tank compels the operator to remove the fire unit from the range to fill tank. This cools the burner below the ignition point. (2) The daily disassembling for clean ing eliminated. (3) Randy means is provided, for draining burner body in case same is flooded - also body will hold a considerable volume of excess . fuel without -spilling out. One Valve operation with automatic control of Air and Fuel mixture makes flooding fur less likely. (4) Both tanks are wet - thus reducing temper-ature and safety blow-outs are provided. I"7. Poison Hazards - As to the affluent gases contaminating the air for breathing, the present unit is considered satisfactory. Laboratory tests show only 3 to 10% of the lead in the gases. The real hazard lies in the twice a day cleaning of the filter chamber and the daily cleaning of generator tubes and flame valves; UP 0009603 Cause of trouble: In this process the deadly poisonous lead compounds are scattered to the .tour 1 ads by scrapers, wire brushes and cloth vri.pers. Careless operators do this with. open food vessels near Remedied in New Fire Unit: The New Fire Unit has approximately the same efficiency of lead removal from the affluent gases, but it is highly efficient in safely disposing of the lead removed. The filter disks holding the lead removed are tightly sealed and are replaced without exposing the poisonous lead compounds. . IS. Operators are often confused by multiplicity of Valves in the Front Panel and make errors in handling same: < Cause of trouble: There are no operating directions on the Valve Wheels and, with three separate valves to manipulate, operators sometimes make careless errors even if they know how. Operation needs 'to be simplified. Remedie d iy? Mi-ivr "Fr-0 Unit: Only two valves to operato and both plainly marked on Wheel what to do On the Flame Valve Regulate Heat as Desired." On the Fuel Valve "Open l/i turn - light Burner - - After 3 minutes open as far as possible." 19. Interru ote d Cooking Servici fill er cnnmb S* - clean ih orcuglx re li.ght same * replace filter - reassemble parts and then Cause of trouble: Construction of unit which makes this twice a day clean ing necessary. . Remedied in Now Fire Unit: Complete elimination of daily servicing end at least 90$ of all Cleaning Operations. 10. Operators Psychological Troubles: Cause of trouble: Because of an excessive amount of cleaning, servicing, breakage and fire hazard, many operators become unduly prejudiced against the unit. They just "donft give a dam" and the Unit gets rough treatment. Remedied in New Fire Unit; A new improved Unit eliminating 90$ of the cleaning; uninterrupted service with no leaky joints, a minimum of breakage and dependable operation will change the operator's attitude of mind. He will like the thing and-give it a fair treatment. 21 Metal Conservation - The present unit, even with steel tanks, uses 2-3/U pounds of cooper bearing metals. This is a headache in certain quarters; Cause of trouble: \"e all know the unnecessary use of Critical Materials cannot be tolerated, under present conditions, for any essential equipment. Remedied in New Fire Unit; The New Coleman Designed Fire Unit uses only one-half pound of Critical Materials - a saving of 2$. . V.