The fieldmen's manual;a handbook of fire prevention adapted to flour mills and grain elevators,
— 1 / _ I H x*/*?- rt/f ss/r/fc/? /r/ff? /. o/r /rp/f*#* /?£>/<? *7 £7/7 or eser/oa// S'/ me O Je/f or/Zufo/vat/'c S fart/rt* (//iters?*/ /Res /star? cej Motor Figure 16. Bureau Standard 591f. The above installation is required for all self-starting motors of the internal resistance or coil connecting type such as the Wag¬ ner BW, Fairbanks, Morse KBV, Century automatic starting and others. Figure 17. ELECTRICAL INSPECTIONS 91 Direct current motors are subject to severe sparking and for that reason must be enclosed. Resistance type starters usually used in connection with them may heat and hence must be enclosed. Where motors are out of sight from the starter, it is required that there be an emergency switch at the motor. There are two reasons for this requirement. 1st — In case any one is working on the motor, it is a protection. 2nd. — When an operator discovers anything wrong with the motor, it provides a means for shutting the motor down at once and this is the point in which we are par¬ ticularly interested. One of the easiest and simplest means of fulfill¬ ing our requirement is to run the low voltage release circuit to a push button or snap switch located at the motor. It must be kept in mind that the push button or snap switch does not fulfill the first requirement in that it does not protect anyone working on the motor. To do that requires a line switch. If these various points covered are set down as you come to them the remainder of your sketch may be similar to figure 17. If your sketch is built up step by step from beginning to end in a logical order there is nothing particularly complicated about it. The final diagram should look as shown in figure 18. Low voltage release is required in all cases. Relays are not absolutely required but if not used fuses must be running size and the time feature of relays is needed in most cases. The low voltage protection is necessary because of the nature of the load found in flour mills and grain elevators. If the voltage becomes low so that the speed falls below normal, the machines and elevators will choke and must be cleaned out before being placed in operation again. GENERAL DISCUSSION OF MOTOR ENCLOSURES. What Motors Shall Be Enclosed. All direct current motors and all alternating current motors using slip rings or sliding contacts in starting or running must be enclosed when located in any building where grain or grain products are handled. All other types of motors must be enclosed when located in dusty or damp places. By special permission en¬ closures may be omitted in fire resistive building. IF IT IS DESIRED TO ELIMINATE ALL POWER CHARGES, THEN ALL MOTORS MUST BE ENCLOSED, except sewing ma¬ chine motors or similar motors without brushes or sliding contacts, rated not exceeding 5 H. P. which cannot be satisfactorily enclosed and are mounted so that they are under the eye of the operator at all times when running. 92 THE FIELDMEN’S MANUAL * Figure 18. ELECTRICAL INSPECTIONS 93 Wliy Motors Should Be Enclosed. Direct current motors and all alternating current motors using slip rings or sliding contacts often throw sparks. The hazard of sparks in a flour mill or grain elevator is too well understood to need further discussion. In addition, these motors are subject to the same hazards as squirrel cage motors. The hazards of the squirrel cage motor are better understood by the examination of a motor. If you look at a squirrel cage motor, you will find slots and openings in the windings and frame for the circulation of air to dissipate the heat generated by the current passing through the wires. Now, if these slots or openings are full of dust and the motor is running with any sort of a load, how is this heat going to get away? It isn’t. Therefore the windings will be cooked and the insulation will be spoiled, resulting in a burned out motor. The result will be the same as if the motor were over¬ loaded. By a proper motor enclosure, a very active fire hazard is eliminated and the LIFE OF THE MOTOR INCREASED. What the Enclosure Shall Accomplish. The first consideration is to protect the motor from dust. That implies that the enclosure shall be dust proof. All motors require ventilation, hence clean fresh air must be provided in the enclosure. All motors need care and attention, hence the enclosures shall be roomy and provide that the motor be accessible from all sides. All motors and electrical equipment are more or less of a fire hazard, hence the enclosure should protect the property from them in case of trouble. In short, the motor enclosure should be dust proof, fire resist¬ ive, accessible and well ventilated. SPECIFICATIONS FOR MOTOR ENCLOSURES. The best construction for motor enclosures from an economical and practical standpoint is metal lath and cement plaster on wood studding. To build this enclosure — construct a framework of 2"x4" (as shown in figure 20, page 94, about six feet high and large enough to enable the operator to get around the motor. The inside of this framework shall be covered with metal lath weighing about 2% pounds per square yard. The metal lath comes about 20" wide and the studding should be spaced accordingly. If it is desired to make a finished job, the metal lath may be put around the outside of the studding, as shown in figure 22, page 95. Plaster with cement plaster. The floor shall be covered with about 2 inches of concrete. The mixture of plaster for outside work is one part Portland cement and 2V2 parts of sharp, clean sand and hydrated lime equal to 10 per cent, by volume of the cement. A small amount of hair may be added. For inside work the most satisfactory plaster is or¬ dinary pulp plaster mixed with 25 per cent. Portland cement. Provide a door, for ventilation, and for a pulley or belt opening. The door shall be two ply wood covered with metal. It shall be hung so that it will close tightly and be self-closing. This may be done by weights but better by a sloping track as is used for fire doors. 94 THE FIELDMEN’S MANUAL 5 k I 0 k O M| O N Q ? n m Bureau Standard 614- ELECTRICAL INSPECTIONS 95 Figure 22. Bureau Standard 614- Ventilation is essential. A pipe (not less than 6 inches in di¬ ameter and larger for large motors) shall enter the bottom of the room and connect with outside clean air. Another pipe shall leave from the top of the room going to outside. Motor rooms in base¬ ment may be ventilated by running the outlet pipe up the building for about 20 feet. The difference in height between inlet and outlet will give sufficient draft. Only in exceptional cases is a fan neces¬ sary. An examination of your motor when running will show air entering on the side and leaving the motor either by the other side or through the frame. If the inlet pipe is brought close to the draft side, the motor will help draw in cool air. Finished room is shown by figure 21, page 94. It is better, if the type of motor will permit, to have the pulley* and belt on the outside of the room. This may be done by leaving a hole in the wall large enough to permit the pulley to pass through. This hole can then be covered with two pieces of plaster board or wood fiber cut out to fit around the shaft or bearing. These may be slotted and fastened on with thumb nuts or slide in grooves. They should slide horizontally, so that they can follow up as the motor is moved on its base to tighten the belt See figure 23, page 96. Where motors are located near walls or in corners, two sides and ceiling are all that would be required, as the building wall may be covered with the lath and plaster. The shape of the room is easily varied to suit conditions, such as sloping roofs and bin bottoms. 96 THE FIELDMEN’S MANUAL Small motors hung from ceilings may be protected by an asbes¬ tos building lumber enclosure. This lumber may be purchased in sheets and sawed and worked like any other lumber. One fourth inch is found to be the most suitable thickness. The asbestos should be placed between the motor and ceiling. See figure 24. Figure 2\. Bureau Standard 61Jt. cur * -5" £A/Ci-OSURE fOH AU.JL /*10T0# MUSVQ mot* CC/X.//* C*. ATTRITION MILL MOTOR ENCLOSURES. Attrition mill motors require special attention in order to com¬ ply with the standard motor installation and protect the motors from the excessive dust found around such installations. Various arrangements have been tried. The one pictured below is being used successfully in a mill in Ohio. The top half is hinged on the back and the ventilation duct at the top can be detached for opening the case for inspection of the motor. Note that all bearings are outside and accessible. Ventilation is obtained by an inlet duct that enters from outside air on the back side near the bottom. The upper pipe vents to out¬ side. The vents are 5". The enclosure is made of 18 gauge iron. See figure 25. ELECTRICAL INSPECTIONS 97 Figure 25. Bureau Standard 61Jt. 98 THE FIELDMEN’S MANUAL WIRELESS TELEGRAPHY. There may be some hazard from lightning coming in on the wires. To protect against this the following regulations should be observed: , , . _ 1st: The pole or tower must be thoroughly grounded with not less than #4 copper wire at each point where it touches the build¬ ing. This grounding must be in accordance with the provisions under grounding in the code. 2nd: The sending wire or wire carrying current to the top of the pole must be kept entirely clear of the building and must be so installed that when swaying in the wind, or when stationary, it will be at all times closer to the grounded pole or tower than it is to the building so that any discharge from this wire will pass to ground thru the ground wire rather than thru the building. At the operators station this wire should be connected by a double throw switch to the apparatus and to ground so that when the equipment is not being used this sending wire can be grounded. 3rd: If the operators station is in the building or on the roof it shall be in a fire resistive room built as outlined under motor enclosures. The wire entering this room shall be so installed that it is at all times nearer to a permanent ground than it is to a combustible material. The idea is to have any discharge that may occur go to the ground by way of a ground wire rather than thru the building. ELECTRIC LIGHTING. The general requirement regarding entrance and outside wir¬ ing fuses, switches, and interior wiring as outlined, apply to electric light circuits also. In addition, the following special features should be noted. GENERATOR. Generators should be enclosed unless located in the power house or some detached building. SERIES LIGHTING. Lights are not permitted in series, since in a case if one light is put out of commission, it subjects the remaining lights to ab¬ normal voltage. THREE WIRE CIRCUITS. Three wire lighting circuits are not permitted, since that in¬ stallation may be equivalent to having two lights in series. TROLLEY CIRCUITS. Lights are not permitted to be taken from trolley circuits, since that is usually 500 V. or more and is subject to a great deal of fluctuation, and may at times be subject to abnormal voltage. Where trolley circuits are used for lighting purposes, it is usually customary to install the lights in series. That of course, is not permitted. ROSETTES. Screw type rosettes, or those having a fuse in the base, are not permitted because of the dust hazard. The dust has a tendency to collect on these rosettes. The vibration of the mill often causes the screws to loosen up which results in arcing at the connection. This arc has, in many cases, set fire to the dust. Drop cords must be soldered direct to the line wires and the connection taped. A one-piece type ceiling button should be used to take the weight of the drop cord. The idea is to do away with the screw and the bare connections. ELECTRICAL INSPECTIONS 99 /c/*- /'o/faae Co//. 7 <S /<? /^ / //?</ Zt/seo f? u/?r?/ng fuse^S' A/ofc:- Afs/rore a /? ft/oe c/ufo S Y&rfer /& t/si ^if the /ow co // mt/sf /?e 00/7/7 ec/et/ //? ft/seJ /es/fes fc /?re>/'e/?f ■S//?#/e /p/?&Lse o^oor-af/on Figure 26. Bureau Standard 591. DROP CORDS AND PORTABLE CORDS. A reinforced cord is recommended for all drop cords. Portable extension cords are required to be of packing house cord, the idea being that ordinary cotton covered cord wears thru by use and may Lecome short circuited. In that case, the top covering will burn freely and of course, constitutes a very serious hazard. LAMPS. All lamps are to be supported in a pendant position. Lamps in a horizontal position may become dust covered and as such offer slight hazard. Nitrogen filled lamps heat to a very high temperature and are therefore not suitable for general use unless in dust proof fixtures. They are however, permitted in power houses and offices without protection. All lamps should be provided with metal guards which will prevent them from being easily broken. The proper illumination of a flour mill is by a few units of high candle power lamps rather than by a great many lamps of small candle power. Gas filled lamps may be used in dust proof receptacles. In Power Houses, Offices and similar dustless locations they may be installed open. 200 watt gas filled lamps in proper fixtures with reflectors have been found to be the most satisfactory and eco¬ nomical size and will replace from three to six ordinary small units. 100 THE FIELDMEN'S MANUAL STANDARD INSTALLATION OF FARM LIGHTING PLANTS. STANDARD INSTALLATION FOR 30, 60 OR 110 VOLT LIGHTING SYSTEM. 1. Generating equipment and storage batteries to be installed in fire resistive room. 2. Generator room built of brick, concrete tile, or metal lath and cement plaster on steel studding. 3. No openings between generator room and mill or elevator or additions unless opening is protected by a standard self closing fire door. 4. Ample ventilation to be provided preferably by vent pipe near floor and ventilator through roof. 5. Main feeder and branch circuits to be installed in conduit. 6. Drop cords, sockets and lighting fixtures to' be of standard type, 7. Branch circuit fuses and switches to be installed in metal cabinet. 8. Wiring must be installed in accordance with the Standard of the Flour Mill and Grain Elevator Insurance Companies. Note — Engines of this type usually have gasoline tank in base. Wire sizes shall be made extra heavy to provide for the voltage drop due to the heavy currents. Unless the wires are extra heavy the voltage at the end of a line will be below normal. If equipment is installed in accordance with above rules, no charges will be made on insurance rate. See figure 27 for proper enclosure. Figure 21. Bureau Standard 801. ELECTRICAL INSPECTIONS 101 STATIC ELECTRICITY. Static electricity is often developed on large belts and bear¬ ings, and unless it is collected and run to ground, trouble may result. The theory is that this electricity is generated by a slight slipping of the belt on the pulley. Should conditions be right, and a contact made in the presence of dust, an explosion would be in order. Some people claim that the so-called static electricity is not dangerous, but since it has been known to ignite oily waste we know that it would also ignite dust. Figure 28 shows a static collector for use on charged belts, both front and side view, with accompanying description. Safety guards around roll pulleys should also be grounded as well as other special places where current may be induced from running machinery. It has been definitely proven that the epidemic of fires in cotton gins throughout the state of Texas in the summer of 1915 was the direct result of static electricity. It is also stated with authority that a majority of fires occurring in threshing machines, a common occurance in the west, are caused from static electricity within the machines themselves. Figure 28. Bureau Standard 83. : -. . ’’ ■ ■ ■= ■ • ■ • ■ fe)M£k CHAPTER VII POWER (EXCEPT ELECTRIC) « POWER (EXCEPT ELECTRIC) 111 CHAPTER YII. POWER (EXCEPT ELECTRIC). STEAM POWER. The principal hazards from steam power house in connection with flour mills and grain elevators are spark hazards, breaching too close to wood work, insufficient clearance around stack, hand¬ ling of ashes, junk on or around boilers, and storage of coal. SPARK HAZARDS: To eliminate the spark hazard, the stack must be first class in every respect, and extend at least six feet above the highest point of exposed roof. The spark hazard is, of course, increased by shingle roofs, loose iron cladding, broken siding, and broken window lights, but this subject is covered under other chapters. STACK AND BREACHING CLEARANCE: There should be at least ten inches clearance between a metal stack where it passes through roof and combustible material, and ventilation should also be provided. The best means of giving ventilation is as illustrated in figure 29. There should be at least fourteen inches clearance between a breaching from a steam boiler and combustible material. Frame roofs have been known to have ignited at sixteen and eigh¬ teen inches from a metal breaching when a boiler has been fired with cobs, but fourteen inches is at present the minimum clearance. Afof*/ £y#cA f/>ru Campus t/6/e /?oo£ Figure 29. Bureau Standard 804- 112 THE FIELDMEN’S MANUAL BOILER CLEARANCE: In frame power house there should be at least thirty inches clearance between boiler setting and side wall. If coal storage is adjacent to boiler it is important that not only the thirty inch clearance ruling be enforced but that the side of coal bin be so constructed that coal cannot spill over into space. Bituminous coal is subject to spontaneous combustion, and the heat of the boiler increases this hazard. The top of the boiler should be kept free from all rubbish and accumulation of dust and coal soot. The top of the boiler is not ordinarily hot enough to cause ignition, but a combination of steady firing and poor ventilation, or a crack in the brick cover¬ ing of boiler will make it so. HANDLING OF ASHES: Fires are still occasionally reported from the placing of hot ashes in combustible receptacles or piling them against a frame partition. The safe way is, of course, to either provide metal cans and place these metal cans on non¬ combustible floor well away from wood partition or wall, or pro¬ vide a storage with concrete walls and concrete floor. SPONTANEOUS COMBUSTION IN COAL: The following sug¬ gestions are offered for safety in storing bituminous coal, although some of them may prove impractical or too expensive under certain conditions: 1. Store coal, if possible, well away from the main buildings of the plant. Never pile it against frame buildings. The storage ground selected should not be of marshy nature or subject to ex¬ cessive drainage from other sources. Avoid admission of air to interior of pile through interstices around foreign objects such as timbers or irregular brick work or through porous bottoms such as course cinders. 2. Do not store near external sources of heat even though the heat transmitted be moderate. 3. The height of the piles should be limited to 12 feet, with a maximum of 16 feet for exceptional conditions. 4. Pile so that lump and fine are distributed as evenly as pos¬ sible, not allowing lump to roll down from the peak to form air passages at the bottom of the pile. TEMPERATURE READINGS. In coal with a tendency toward heating the temperature rises are comparatively gradual and if detected in time, complete com¬ bustion may be prevented by rehandling. If the ignition point is reached, a fire may burn for a considerable time in the interior of the pile before it becomes apparent from the outside. For the detection and prevention of fire, the installation of hollow iron pipes staggered every 50 feet through the piles, driven within a foot or so of the bottom, will permit the lowering of a thermometer. These pipes should be pointed and closed at the bottom to facili¬ tate their installation and provided with a stopper for the opening at the top to prevent the admission of air. FROM PENNSYLVANIA RAILROAD COMPANY* INSURANCE DEPARTMENT. In 1915, the Pennsylvania Railroad Company laid in at some twenty different locations, a supply of a million and a half tons of bituminous coal valued at something over two million dollars. In POWER (EXCEPT ELECTRIC) 113 °yer a year not a single loss was experienced, believed to be attrib¬ utable in a large measure to the adoption of certain precautions. A supply proportionate to its average consumption was stored on each division at some point where it neither offered nor wa3 subject to exposure from adjoining property. Bituminous coal used by railroads is generally of two kinds, the ordinary freight locomotive coal and the more gaseous or vola¬ tile for passenger locomotives. Of the two, the likelihood of spon¬ taneous combustion is believed to be greater in the former, as oxidation has a tendency to increase as the fineness of the coal approaches that of dust, particularly when mixed with lump coal of such a size that the interstices permit the flow of a moderate amount of air into the interior of the pile. This conclusion is borne out somewhat by comparative temperature readings which indicated an average excess of 10 degrees. In other words, the high volatile matter in coal does not of itself increase the liability of coal to spontaneous heating. Where pipes are installed it is a good practice to take tempera¬ ture readings three times a week during the warmer months and once or twice a month in winter. At several points where the coal was stored near shop plants, temperature readings were taken daily. The charts of these daily readings for a period of nine months developed many interesting facts, for instance, in one pile of coal where the readings in 19 other pipes were almost iden¬ tical in 3 of the pipes in the same pile the temperature showed an average excess of 20° over the other pipes, believed to have been due to marshy ground under that portion of the pile in which the 3 pipes were located. At another storage point where the temperature averaged about 40° F. at 27 pipes, at one pipe in the pile a temperature of almost 50° above the average was recorded, with a maximum of about 112°. This condition was believed to be due to the collection of gases in a pocket formed by large lumps of coal in the interior of the pile. The maximum tempera¬ ture allowed was 150°, or, if the temperature remained constant at an unusually high point, instructions were issued to rehandle the coal. If once rehandled, coal seldom heats spontaneously again. The highest temperature recorded was 138°, and as far as we know, it was unnecessary to rehandle any of the coal. POWER HOUSE CONSTRUCTION: Fire resistive construc¬ tion is understood to mean solid concrete and brick walls, roof, and floor, or brick or concrete with metal on metal I beams roof, (no wood permitted in the construction). The openings from such a power house to other parts of the plant must be protected with standard fire doors or wire glass windows. This, of course, is the ideal construction and takes the lowest rate. All power houses should be cut off from the mill as much as possible, consequently in brick or similarly constructed power houses, all communicating openings should be protected by standard fire doors or shutters. 114 THE FIELDMEN ?S MANUAL COB HOUSES: There is a distinct hazard in the storage and handling of cobs for fuel. They may be stored in a well built, substantial cob room having a cement floor, and should be spouted into this room through a metal spout open at top for a space of two or three feet where it enters the cob house, so that fire cannot back up the spout to the elevator. Shucks and dust must not be stored in the same room. The cobs must not be permitted to accumulate around the boiler and some provision must be made to keep them from flowing into the boiler room while being shoveled. For this purpose an inside partition or room about 4' x 4' x 6' should be built of removable slats and with sloping roof at the opening from power house to cob house. A better way to handle the cobs is in a fire resistive boiler room with a fire resistive cob room over the roof, having a metal spout reaching nearly to the floor of the boiler room. This will permit the cobs to flow only as fast- as they are used. The spout to the cob room should be open for about three feet on top where it goes through room to eliminate the possibility of the cobs back¬ ing up into the elevator when the room is full, and communicating the fire in case the cobs should become ignited in the cob room. Cobs and litter should be carefully cleaned up from the floor between the cob room and boiler, but the sweeping should always be done from the cob room to the boiler, otherwise sparks from the boiler may be swept back into the cob room. GAS AND OIL. ENGINE HAZARD. The hazard from internal combustion engines may properly be divided into two general classes. 1. There are certain inherent hazards from the engines them¬ selves, which are largely determined by their construction and installation, and which are not under the direct control of the operator. 2. Then there is the hazard in the handling of the fuel and care of the equipment. That is under the direct control of the operator, and as such, the human element enters in, and conse¬ quently it is of primary importance. Our rules governing the installation of these engines were promulgated to guard against these hazards, and the construction and installation has been fairly well standardized, but the fuel is handled by the operator, and careless handling of fuel has probably been responsible for more fires than the inherent hazard of the engine itself, and that partic¬ ular point should be carefully checked up by the inspector. Before going further into detail, a short discussion of internal combustion engines will be beneficial. An internal combustion engine is one in which the fuel, used for the generation of power, is burned Within the power cylinder. There, are two general types of this engine. One is operated on what is known as the Otto Cycle, and the other on what is known as the Deisel Cycle, and practically all internal combustion engines used in connection with our work, are of one type or the other, or some modification of them. POWER (EXCEPT ELECTRIC) 115 On either engine, the events of the cycles are. (1) suction, (2) compression, (3) combustion of the fuel or explosion, (4) expan¬ sion, (5) exhaust then repeat. A four cycle engine is one in which all the events or one cycle is completed in four strokes of the piston or two revolutions of the flywheel. Likewise the two cycle engine is one in which the events are completed in two strokes of the piston or one revolution of the flywheel. In the Otto cycle, air and fuel are drawn into the cylinder at the first stroke and are compressed during the second stroke. Ignition takes place near the end of the second stroke and is caused by some external means, such as an electric spark. The automobile engine is a good example of this type. In the Diesel cycle, air only is drawn into the cylinder during the first stroke. During the second stroke, air only is compressed to a very high pressure resulting in a great temperature increase. This pressure may run as high as 500 pounds per sq. in. and the temperature to' 1200° F. At the end of the second stroke and early in the third stroke, the fuel is injected into the cylinder and burns as fast as it comes in. The important point to remember is that the temperature of compression (1200° F.) is sufficient to cause the ignition of the fuel. No external means is necessary. In our work, we find comparatively few engines of the Diesel type, but a modification known as the Semi-Diesel type is very common. The Fairbanks type “Y” is a good example of this. The Semi-Diesel engine does not develop high enough com¬ pression to produce ignition, so ignition is aided by some other means, usually in the nature of a “hot ball,” which is heated by external means to start with, but which furnishes its own heat when once in operation. This type must not be confused with the old hot tube or torch ignition engine. The Diesel engine can be operated on most kinds of fuel oil, but due to its high compression it must be very strongly built, and requires a very substantial compression to introduce the fuel into the cylinder against the compression pressure of 500 pounds, or more. It also requires compressed air or some other auxiliary means for starting. For these reasons, the Semi-Diesel type is favored, since it is much simpler of construction and contains many of the advantages of the Diesel type. However, it has one very objectionable feature. It is necessary to heat the “hot ball’' before starting. That is usually done by means of a gasoline torch and therein lies the danger. The ball itself is protected by a cap, and although there is some element of danger, that is not regarded as serious. The hazard is in the handling of the torch, and since that is handled by the operator, he is the man to talk to. Ask him what precaution he uses. Discuss the subject with him and impress him with the necessity of carefully handling it. Since the fuel is not injected until the end of the second stroke preignition cannot occur in the Diesel engine, and since there is no carburetor, back firing cannot occur, and therein lies a de¬ cided advantage, from a fire prevention standpoint. 116 THE FIELDMEN’S MANUAL FUEL SUPPLY. One important point to be considered in either type of engine, is the fuel supply. All Otto cycle engines (or any engine using gasoline for fuel) must have pump feed. Diesel engines may have pump feed or they may have gravity feed to the injector pump, provided they are installed as shown in figure 30. With the increased price of gasoline, there has been a general attempt on the part of manufacturers to perfect a means whereby gasoline engines can be run on oil. Unfortunately the compression cannot be easily changed. Kerosene requires a lower compression temperature than gasoline. This can be accomplished by intro¬ ducing water, with the kerosene, which reduces the temperature. By this means, gasoline engines can be operated successfully on kerosene when they are once warmed up. They are usually warmed up by starting on gasoline. Several carburetors are on the market using gasoline to start on, which, when the engine is warmed up, can be switched to kerosene. There is no particular hazard when the fuel is handled as specified in the schedule. There may be considerable hazard, however, if gasoline is squirted by hand into the mixing chamber. Even that method for starting the engine is too slow for some of the elevator operators, so they warm up by burning gasoline on the outside of the cylinder, or by building a fire under it. That may satisfy the operator, but it does not the Insurance Companies. Either convince the operator of the error of his ways, or re¬ lieve your Company of liability. Of course, the former is prefer¬ able, because cancellation should never be resorted to except as a means of last resort, but that practice is so inexcusable, that it does not admit of any compromise. HOT TUBE ENGINES. Hot tube engines are not permitted except in fire resistive power houses. This engine is so far out of date that it is nearly obsolete, and anybody using one now should be regarded with suspicion. This type of engine must not be confused with the Semi-Diesel type using a torch for starting. TANK IN BASE. The chief hazard of these engines is that gasoline in them is in the building. It must be carried in and poured in the tank by hand. The handling of the fuel is the chief danger, and is enough to warrant the special charge which they take. When located in dusty or dirty places the hazard is sufficient to warrant you in declining to' recommend the risk. EXHAUST PIPE. The exhaust pipe and muffler may be coated with carbon or soot, either dry or oily. The hot gases exhausting thru this accumu¬ lation may cause it to burn or even explode, which may heat the pipe red hot. Even under normal conditions, the exhaust pipe may be very hot, hence it must always be protected. It must be kept at least six inches from all combustible material and where it passes thru partitions, side walls, floor or roof, must be pro¬ vided with a ventilating thimble, allowing a clearance all around of six inches. This clear space is important. We have often seen exhaust pipes run thru a frame side wall with a supposed insula- POWER (EXCEPT ELECTRIC) 117 ARRnrtGEMEn T \ PFOT&C T/Ofi or OIL. FEED RIPinO FOP FLO/T FEED 'SPEC/fU- PERFI/SS/OrV REQUIRED. -SEE SPEC / F tCAT IO/VC. Figure 30. Bureau Standard 639. /&;&/ 118 THE FIELDMEN’S MANUAL tion of brick, cement, asbestos, or some such material around it. It looks nice, but it is a decided hazard. We have had many fires caused by heat being transmitted thru such material to the wood work. Insist on the clear space. See figure 31. In oil engines, the exhaust pot and exhaust pipe must be given special attention. There is always more or less of an accumulation of heavy oil or very oily carbon which collects in the exhaust pot. This will burn out sooner or later and heat the pot and pipe red hot. We have seen the results of several fires and near fires from this cause. In one particular case, bags were set on fire over a foot away from the pipe. These engines, should, if possible, have their exhaust lead from the exhaust pot under ground and on a slight slope, ending near a gutter or incline, so the residue will drain away from the building. If that is not pos¬ sible, there should be a pit outside the building with the exhaust pipe entering horizontally under ground, and leaving the top in a vertical position, and extending in the air six feet higher than any exposed roofs. This exhaust pit should be as far away from the building as possible, and should have a loose cover as near the size of the pit as possible, loosely fastened by bolts so that it can be raised at least a foot, but no higher. This cover is to provide a means of release, in case of a fire or explosion. This pit should be drained. A pet cock at bottom of exhaust pot to be opened when engine it not running is advisable if the arrangement is such that exhaust pot does not drain automatically. Keep in mind that the idea is to drain the residue away from the building and get it into the open, if possible. GAS PRODUCER POWER. The operation of the gas producer is usually not very well understood by the layman. A short discussion of it will be of great advantage in measuring its hazards. In the usual process of gas making, coal is subjected to destruc¬ tive distillation, heat being furnished by an exterior fire and leav¬ ing coke as residue. Another process is to pass a small quantity of air with or without steam or vapor thru a thick bed of fuel. The coke, instead of remaining as a by-product, is utilized in mak¬ ing the gas. This is the principle of the gas producer. The majority of gas producers in use in this country, are one of three types, viz; suction type, pressure type, down draft type, or a combination of these. For units below three hundred (300) horse power, the suction type is particularly suitable, and it is the one with which we are principally concerned. Suction producers usually consist of three elements — the gas producer or furnace; the steam generator or boiler; the gas cleaner or scrubber. To start operations, a fire of wood is made on the grate of the producer, the air necessary for combustion being sup¬ plied by a hand blower. As soon as the fire is “going" good, the gas producing fuel is added. The generation of gas starts at once, but the gas is of rather poor quality. This quality can be roughly tested by lighting the gas at a small test cock. The color of the flame indicates the quality of the gas. The 'smoke and poor gas POWER (EXCEPT ELECTRIC) 119 formed during starting is discharged to the outside by purge pipe As soon as the gas becomes of the proper quality, the engine is started and the hand air pump stopped. The suction of the cylinder draws the air necessary for combustion thru the producer. The gas on the way to the engine is drawn thru the steam generator. This gas, being hot, generates steam at low pressure. The steam is taken up by the air being drawn into the base of the producer. In passing up thru the lower part of the fuel bed, the oxygen united with the fuel, causing combustion, and liberating carbon dioxide gas and hydrogen. In passing thru the remainder of the fuel bed, this carbon dioxide is split up and unites with more carbon, forming carbon monoxide. This is the gas used by the engine, but on coming from the producer, it is very dirty and smoky, so after going thru the steam generator, it is passed thru the scrubber. This usually consists of a tall steel or iron cylinder, filled with coke, over which water is sprayed. The gas enters the bottom, and in working up thru the coke against the spray of water, has all the dirt and tar washed out of it. Under normal operating conditions, the pressure inside the producer is lower than the outside pressure, hence there is very little chance for gas to leak out. On starting, however, when the hand pump is being used, there is some slight pressure, and the gas may leak out or the test cock may be open. The chances of this are very small, but we have had some fires which we attribute to this cause. The remedy is to require the producer plant in a power house, well ventilated and properly cut off from the mill. The exhaust pipe presents the same hazard as any gas engine, and should be protected accordingly. Where pressure systems are used, the gas is usually stored in some suitable container and is often used for other purposes than power. There is, of course, a serious hazard in that, and such plants should be located in detached power houses. INSTALLATION RULES. The rules covering installation of internal combustion engines are fully set forth in the Rating Schedule, pages M-9, 10 and 11. CHAPTER VIII MACHINERY and SPECIAL HAZARDS - MACHINERY AND SPECIAL HAZARDS 121 CHAPTER Till. MACHINERY AND SPECIAL HAZARDS. No attempt will be made here to discuss any machinery or special hazards not commonly found in flour mills or grain eleva¬ tors. When the occupancy is mixed, or the process of storing or milling gram is combined in the same building with some other class of storage or process of manufacture, the risk must be judged on its merits, and report submitted to the office under¬ writer. GLUE POTS, SOLDERING POTS AND SOLDERING IRONS. Glue pots, soldering pots, and soldering irons are necessary equipment to any successfully operated flour mill and elevator They possess certain hazards just the same as many of the machines necessary to the process have certain hazards. Although they have some hazard it is a mistake to order then} out indiscriminately, just the same as it would be a mistake to order out any necessary machine. Where electric current is available electric glue pots should be used and electric soldering pots and irons may be recom¬ mended. However, the latter are not practical for all uses and it will usually be necessary also to have one for use in connection with a blow torch or gas furnace. Electric babbitt kettles are on the market but they, are of small capacity and very expensive. In cupolas of elevators and other dusty places they add greatly to the safety of babbitting boxes and should be recommended. However, if the voltage is low they may not get hot enough so that good work can be done and it may then be necessary to resort to the gasoline furnace. The proper way to combat the hazard of these devices is to educate the operators to exercise safety and care in the;*' use rather than by making arbitrary requirements impossible of being carried out and thereby arousing the animosity of the operator and losing his co-operation in other things that are practicable. MOISTURE TESTERS. There is no objection to the use of a gasoline moisture tester such as the Brown Duval, provided it is located in the office, labor¬ atory, or some other clean dustless location, and that no gasoline, except that in the tank of the tester, be permitted in the room or building adjacent thereto. The hazard is more from the careless handling of the gasoline than from the tester itself. Some sort of moisture tester is essential to' intelligent milling, and their slight hazard is not sufficient to prohibit their use. GRAIN DRYERS. There are two general types of grain driers. The one most commonly used consists of a steam generator, which may be and usually is the boiler furnishing the steam power and a set of steam coils over which the air to be heated is drawn by a large suction fan. The grain is contained in a large upright metal drum or column of louvres, and the hot air is forced through the grain as it passes down through. Another fan forces cold air through the grain as it passes through the last section of the drum. The hazard from these steam grain driers is in the installa¬ tion of the steam generator and from the accumulation of dust 122 THE FIELDMEN’S MANUAL in the drier coils. The steam generator should he installed the same as a boiler furnishing power. (See Specification in Chapter VIII.) To reduce the hazard from the accumulation of dust in the coils, a steam connection carrying the full steam pressure should be placed in a convenient location and a steam hose attached to it with suitable nozzle. With this the dust can be thoroughly removed from the interior of the set of coils. This should be done frequently, or as often as any quantity of dust accumulates. The operator should be cautioned against the practice of first turning on the steam and then starting the fans. A large mill in Buffalo was set on fire by the operator attempting to heat the mill with the drier coils. Three other fires are on record as hav¬ ing originated in the drier coil, and in at least two of these three cases the steam was turned on before the fan started or left on after the fan had b^en stopped. The necessity for clean steam coils and the steam being turned on only during the time that the fan is running, cannot be emphasized too strongly. There is not considered to be any fire hazard in the drums, and none in the fans other than that of any fan with fast running bearings operating on more or less dust laden air. The other general type of grain drier, of which the Randolph Drier, (see figure 32) is typical, operates the same in its drying processes as the steam dryer, but the generation of heat is entirely different. A hard coal burning furnace is used, and the gas and some small amount of unburned air brought in over the top of the fire, is drawn directly through the grain. A short smoke stack is provided for draft while the fire is being started, but as soon as the drying begins this is closed, and all gas and smoke passes through the grain. The hazard here was supposed to have been in the installation of the furnace, and the specifications shown in the cut were adopted. Recently one fire has been reported from a piece of wood having lodged in the grain outlet stopping the flow of grain. Either the grain or the wood, and probably both, were fired by the continued action of the heat. The assured should be warned against the possibility of foreign material entering the drying column and stopping the flow of grain. Each installation will present its own problem along this line, but the best remedies will probably be found to be either a screen at the point where the grain enters the drier, or a scalping shoe in the grain stream at about this point. GRAIN SEPARATORS. There are a large number of makes and kinds of grain sepa¬ rators, ranging from the small seed separator with small slow running fans to the large ones designed for use in terminals, and the fire hazard may be considered to be somewhat proportionate to the size. 