Generator
Conversions

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Dual Fuel Installation

IMPCO SERIES

Impco Model E Regulator

Impco Model PE Vaporizer

Impco Model L Converter

Impco Model J Vaporizer

Cobra
Two-Stage Converter

IMPCO
VFF30 Filter

FL-219 solenoid shutoff valve

FL-416-12V shutoff valve

FL-418 12V Fuel Lock

Alternate Fuels Technologies, Inc

Principals of Natural Gas Conversions
& Propane Conversion Kits

Generator Propane Conversions & Natural Gas Conversion Kits

The Garretson systems of gaseous fuel carburetion are designed to run internal combustion engines with gaseous fuel in the simplest, most economical manner for top performance and lowest emissions for propane conversions and natural gas conversion kits for alternate fuels.

The Garretson fuel systems operate using the venturi principle. As air is drawn into the engine by the piston, it must pass through a venturi in a liquid fuel system acts on a float and needle valve to draw in fuel, the vacuum in a gaseous system acts upon a diaphragm in a fuel controller (zero governor). As the diaphragm is drawn toward the source or the vacuum, an attached lever opens a valve and allows the propane or natural gas fuel to flow through the carburetor. The proper fuel air mixture is then obtained be a mixture adjustment in the fuel line between the fuel controller and the venturi.

This sounds very simple, and it is. However, the key to satisfactory performance in the venturi system is the sensitivity of the fuel controller throughout its operating range whether using the natural gas conversion or propane conversion kits. A properly set fuel controller (zero governor) using a rubber seat and spring tension against an orifice will shut off the flow of fuel when the engine is not running. Yet the slightest amount of vacuum should cause the seat to move and allow gas to flow. Also, if the fuel controller allows fuel to leak through at shut down, hard starting and the danger of fire will result. In either case, the fuel controller should be readjusted per the specific instructions for the unit.

Besides a sensitive fuel controller, an accurate and constant fuel pressure leading into the fuel controller is vital for the top performance. In remote tank supplied propane gas systems a primary regulator feeds the fuel controller a constant gas pressure regardless of tank pressure or flow. Most natural gas and domestic propane gas generator conversion installations have a constant pressure regulated at the storage equipment, eliminating the need for a primary regulator.

Although there are other methods of designs of gaseous carburetion for small engine conversions, we feel that the venturi principle provides a simple, easy to service small engine conversion kit with no need to sacrifice performance or exhaust emission levels. A properly adjusted venturi system from liquid to gaseous carburetion, either the spud in method, the adaptor method or carburetor replacement method. The spud in conversion kits use the existing gasoline venturi with a fuel delivery tube installed in the area of greatest vacuum whether you install the natural gas or propane conversion kits. The adaptor conversion kit method uses a special venturi and is placed between the carburetor and the air cleaner. The replacement conversion kit method uses a specially designed carburetor to replace the existing gasoline carburetor.

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Cost - Serviceability - Durability - Versatility

The fuel controllers, regulators, vaporizers and two stage combination units in our small engine conversion kits have been designed to give optimum performance using the simple venturi carburetion principle. Due to this design the full range of fuel controllers can be used for field replacement on similar natural gas or propane conversion systems. Many universal parts are used, especially those parts most commonly needed for rebuilding and repair. Most of the units feature easy replacement of orifices and valve seats without costly unit disassembly.

These features along with quality construction provide years of trouble fee service from our generator conversion kits for dedicated or dual fuel conversion for alternative fuels.

Reliable Automatic Starting

The unique Garretson Adjustable Auto Prime is available as an option for all our small engine conversion kits. After installation, you can easily adjust the Auto Prime to meter a precise amount of fuel from the fuel controller to the engine for starting. Most other systems use a controlled leakage or wild flow electric primer which often leads to flooding or rich air fuel mixtures.

The Auto Primer can be wired so that the unit is activated either automatically each time the engine starts or at selected times by an operator. By using a double throw selector switch it can be operated either way.

Auto Primer Operation

If the Auto Primer is properly installed and adjusted, set and leave the toggle switch in the Auto Prime position. Then, every time the engine is cranked, the Auto Primer will automatically meter the proper amount of propane or natural gas for starting the engine. The Auto Prime will start the engine regardless of the throttle position. This primer is optional with our natural gas or propane conversion kits.