Gasseous Carbureton Info

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CONVERSION KIT GARRETSon VACUUM IDLE ~ INSTALLATION INSTRUCTIONS f@~' GENERAL INFORMATION PLEASE READ THE ENTIRE INSTRUCTIDN PRDCEDI,JRE BEFDRE ATTEMPTING TO COMPLETE THE INSTALLATION The Garretson gaseous fuel conversion kits have been designed to provide a basic set of equipment to convert . an internal combustion engine to gaseous fuel. Most of the conversions can be accomplished in 30-40 minutes using common hand tools. There are a few instances where an electric prill or threading equi
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  GARRETSon CONVERSION KITINSTALLATIONINSTRUCTIONS VACUUM IDLE ~ f@~'  GENERALINFORMATION PLEASEREADTHEENTIREINSTRUCTIDN PRDCEDI,JREBEFDREATTEMPTING TOCOMPLETE THEINSTALLATION The Garretson gaseous fuel conversion kits have beendesigned to provide a basic set of equipment to convert.an internal combustion engine to gaseous fuel. Most ofthe conversions can be accomplished in 30-40 minutesusing common hand tools. There are a few instanceswhere an electric prill or threading equipment are need~ ed. . . , series of diagrams ~howing the recommendedjDipiqg forvarious types of systems. The last section detail~q' pro-cedure for first time starting and normal operatlon .As an aid to installation, this procedure is divided intofour parts. The first section concerns the actual conver-sion of the carburetor. The next section concerns proper.placement of the ze'ro governor. This is followed by aAlthough, most of the kits are designed for a particularengine model, there is always a chance that because ofthe specific engine application the conversioo cannotbeinstal.led as the instructions show. If there appears to beno alternate way to install the kit, either write or call usas we may be able to recommend how to modify the kitor suggest another set of equipment. (ãã.. .ãã.ãã.. ãã..ãã.. !WARNING! -- ~ ~, ~ .. ' THE STANDARD KITS AS SHIPPED CONFORM TO THE NATIONAL FIRE PROTECTION ASSOCIATION ,(NFPA) PAMPHLET 58 REQUIREMENTS FOR USE OF GASEOUS FUELS AS A MOTOR FUEL OUTDOORS.ã IF THE CONVERTED ENGINE IS TO BE HOUSED IN AN ENCLOSURE OR USED INDOORS, ADDITIONAL ~ I l I I EQUIPMENT IS REQUIRED TO POSITIVELY SHUT OFF THE FUEL SUPPLY IF THE ENGINE SHOULD FAIL ,, r;;~~J;;;;~~~~JI~~~~bC:;0~~ ~~ET~6!:~~gi~YsSJ~~,~~O~R TTHHEE z~~~~~¥~~~~~}~~, NFPA PAMPHLET 58.'l:oR A COPY OF PAMPHLET 58, WR,'TE THE NATIONAL FIRE PROTECTION ASSOCIATIQN, BATTERY---.J'MARCH PARK, QUINCY, MA 02269. 3- . . . . . . . . ~ - . - . . . . . . . . _ - - - - - - , . . . . . , . . . , ~ . . . , ~ , f    ,, (1) Thread sealing compound should be used on all pipe thread fittings between the zero governor and the fuelsupply, being careful not to get any inside the fittings. This could allow excess compound to collect on valveseats and orHices and cause hazardous leakage and poor performance.(2) If c,opper tubing is used, it should be K or L having a minimum wall thickqess of 0.032 inches. l (3) After piping is complete, turn on the gas and use a soap solutIOn )'19S for leaks.  \..-.. ~ ~ ~ ~ . . . . . . . . . . ã _ - - - ~ ~ ~ ~ . . . , ~  The installation procedure for the carburetor section is detailed on an enclosed sheet. After completion of thisprocedure continue with the next section. ZEROGOVERNOR MOUNTING PLEASE READ THE FRONT PAGE WARNINGS The Zero Governor should be located according to the recom-mendations included with it. If this sheet is not available, pleasefollow the following suggestions.The Zero Governor should be mounted as close to the car-buretor as possible with the diaphragm oriented in a verticalplane. This helps to minimize the effects of gravity ondiaphragm travel. The unit should also be placed for easy ac-cess to the lock-off adjusting screw and primer if provided.Refer to the piping diagram for the recommended pipingsystem; and before installing the fuel supply line, be sure thatthe gas pressure is no more than the maximum inlet pressureshown on the cover of the zero governor. If the pressure isgreater, leakage Gould result in a fire hazard and or hard start-ing.Flexible piping to the inlet should be used to prevent crackingfrom vibration if the zero governor is mounted on the engine orother vibrating surface. Also piping to the inlet should be ofsufficient size to allow full flow to the zero governor. This isvery important in natural gas installations as any restrictionssmaller than the zero governor orifice can affect engine perfor-mance. If a solenoid valve is used ahead of the zero governor inthe low pressure line, it should have an orifice at least as big asthe orifice in the zero governor.When an electric solenoid primer is used, follow the wiring andadjusting instructions furnished separately.Select and install the outlet fitting into the zero governor takingcare not to allow any dirt to enter the outlet. Some zero gover-nors may already have a fitting installed at the factory.After installation of the fuel hose between the zero governorand the carburetor turn on the gas and test the system for leaksat the piping joins using a soap bubble solution or suitable gasdetection device. MODEL SOAND - ~68-REGULATOR TO CARB t 419-02  /ELBOW \ I  PRINCIPLES OF GASEOUS CARBURETION The Garretson systems of gaseous fuel carbu-retion are designed to run internal combustionengines with gaseous fuel in the simplest, mosteconomical manner for top performance andlowest emissions.The Garretson systems operate using theventuri principle. As air is drawn into the engineby the piston, it must pass through a venturiwhich creates a vacuum proportional to theamount of air being used. Whereas the vacuumcreated by the venturi in a liquid fuel system actson a float and needle~alve to draw in fuel, thevacuum in a gaseous system acts upon a dia-phragm in a fuel controller (zero governor). Asthe diaphragm isdrawn toward the source of thevacuum, an attached lever opens a valve andallows the gaseous fuel to flow through to thecarburetor. The proper fuel-air mixture is thenobtained by a mixture adjustment in the fuel linebetween the fuel controller and the venturi.This sounds very simple, and it is. However,the key to satisfactory performance in the ven-turi system is the sensitivity of the fuel controllerthroughout its operating range. A properly setfuel controller (zero ~bvernor) using a rubberseat and spring tension against an orifice willshut-off the flow of fuel when the engine is notrunning. Yet the slightest amount of vacuumshould cause the seat to move and allow gas toflow. Ifthe spring force is too great and requiresgreater vacuum to open the device, a flat spot orsluggish progression off idle will develop with apossibility of lean mixtures and power losses atfull load. Also, if the fuel controller allows fuel toleak through at shut-down, hard starting and thedanger of fire will result. In either case, the fuel ~VACUUM controller should be re-adjusted per the specificinstructions for the unit.Besides a sensitive fuel controller, an accu-rate and constant fuel pressure leading into thefuel controller is vital for top performance. Inremote tank supplied LP-Gas systems a primaryregulator feeds the fuel controller a constantpressure regardless of tank pressure or flow.Most natural gas and domestic LP-Gas installa-tions have a constant pressure regulated at thestorage equipment, eliminating the need for aprimary regulator.Although there are other methods or designsof gaseous carburetion, we feel that the venturiprinciple provides a simple, easy to serviceconversion with no need to§acrifice perfor-mance or exhaust emission levels. A properlyadjusted venturi system can produce resultscomparable to other more complicated sys-tems.There are three ways to convert a venturisystem from liquid to gaseous carburetion, El.i.. .ther the spud-in method, adaptor method of' replacement carburetor method. The spud-inkits use the existing gasoline venturi with a fueldelivery tube installed in the area of greatestvacuum. The adaptor method uses a specialventuri and is placed between the carburetorand the air cleaner. The replacement methoduses a specially designed carburetor to replacethe existing gasoline carburetor.If you desire to know more about gaseouscarburetion, we have a technical paper entitled Converting Liquid Fueled Engines With LP-GasCarburetion, A copy will be sent on request. GAS ATPOSITIVE PRESSURE  The heart of a venturi type gaseous carburetion system isthe zero governor. Zero governors may be known by manynames including fuel controllers, vacuum regulators, de-mand regulators, last stage regulators, second stageregulators or negative regulators.Regardless of the name, all have the same function.The zero governor serves the same purpose in a gaseousfuel system as the float and needle valve in a gasolinecarburetor. Both regulate fuel flow from the fuel inlet intothe main fuel jet. In a gasoline system, the float and needlevalve allows the liquid fuel level (pressure) to vary asneeded to meet the fuel demands of the venturi. Usinggaseous fuels, this job must be done with a vacuumsensitive diaphragm and a very sensitive relief valve,holding a pressure level of zero or at slightly subatmosphericpressure..... While a zero governor has the same basic elements ofacommon pressure regulator; namely, a diaphragm (sens-ing element), a spring (loading element), and seat-orifice(restricting element), they differ in their relationship to eachother.In the common pressure regulator, when pressure isapplied to the inlet, fuel flows through the outlet if it is notplugged or restricted. This is not the case with a zerogovernor. Fuel will not flow unless vacuum is applied to thediaphragm chamber.In a zero governor, a round orifice and a flat rubber seatto control fuel flow are attached to one end of a lever. A pivotpin with spring force is attached to the otherside ofthe lever.A zero governor can be visualized as a teeter totter orseesaw with a fifty pound child on each end of the lever.Equal forces balance the lever. The system is balanced bythe fuel pressure trying to force the valve open and thespring tension acting to keep the valve closed. A smallamount of force applied to one end of the lever will upsetthe balance and cause movement.This force occurs when the venturi suction applied to thediaphragm causes the higher atmospheric pressure on theopposite side to move the diaphragm towards the lever.When the diaphragm applies force on the spring end of thelever, the balance is upset, the relief valve opens and gasis allowed to flow.If gas pressure greater than the spring force is appliedto the inlet, the excess pressure forces past the orifice andcauses a leaking condition. However, if too much gaspressure flows into the body case, the diaphragm lifts andassists the spring in closing the valve. A zero governor can not be designed as a safety devicebecause several factors can cause it to function im-properly. The most common cause of trouble is dirt on the seat.Dirt inthis area can hold the rubber seat open and allow fuelto flow continuously reSUlting in unsafe operating condi-tions as well as causing flooding and hard starting condi-tion. Conversely, ifthe spring force is excessive, itrequiresmuch more vacuum to move the diaphragm causing theengine to be too lean to idle properly or develop a flat spot·when progressing from idle.If the primary pressure applied to the orifice increasesor decreases for some reason, and the spring force is notadjusted, this can upset the balance and cause gas to leakthrough or be locked off too tightly.o'Every detail ofthe zero governor's design; parts, mate-rials and manufacturing methods, must be carefully con-sidered. The diaphragm should have as much area aspractical. It must also be strong, yet flexible for sensitivity.It should be resistant to the gas and various contaminantsand have good mobility to operate the lever. Garretsonproduces diaphragms with molded convolutions from sili-con rubber material which are flexible down to a tempera-ture of -50 degrees Fahrenheit.The rubber seat must be flat with a good surface finishand soft enough to seal without excessive force but not sosoft that it will indent and make a footprint .The orifice must also be flat with a good finish, andsharp, but not so sharp that it will cut the rubber seat. Theseat should move against the orifice squarely with a springthat has a fairly constant force or rate . We at Garretson have been building zero governorsfor over 35 years. We have many different sizes andstyles in our line which can be used with propane andnatural gas at various pressures to suit many sizes ofengines and applications. Ifyou have any questions ongaseous fuels or equipment, please give us a call. WARNING The settings on the zero governor and the primary regulatorare made at the factory on each and every product. Please do not attempt to change these settings unless you have thetools, gauges and experience. Never attempt to richen or leanthe main fuel air mixture with the spring adjustments of theregulating devices.
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