Filler
When liquid fuel is transferred into a vehicle tank or cylinder from a pump at the fuel station / filling station, it is transferred to the filler fitting on the vehicle.
The type of filler used varies from country to country and there are generally threee types:
ACME thread
This type has a threaded fitting onto which the bowser nozzle is screwed before the trigger is pulled to establish a seal before fuel transfer. This type is used in Australia, USA, Germany, Austria, Belgium, Republic of Ireland.
'Dutch' Bayonet
This type establishes a gas proof seal by a push and twist action. This type is used in the United Kingdom, Netherlands and Switzerland.
'Italian' Dish
This type is used in Italy, France, Scandinavia and Portugal.
Adaptors are available that allow a vehicle fitted with a particular system to refuel at a station equipped with another system.The fill valve contains a check valve so that the liquid in the line between the filler and the tank does not escape when the pump nozzle is disconnected.
More than one tank on your vehicle
In installations where more than one tank is fitted, T-fittings may be used to connect the tanks to one filler so that the tanks are filled simultaneously. In some applications, more than one filler may be fitted, such as on opposite sides of the vehicle. These may be connected to separate tanks, or may be connected to the same tanks using T-fittings in the same manner as for connecting multiple tanks to one filler.
Hoses, Pipes and Fittings
The hose between the filler and tank is called the fill hose/fill line. The hose or pipe between the tank and the converter is called the service line. The fill hose / fill line and the service line both carry liquid under pressure.
The flexible hose between the converter and the mixer is called the vapour hose or vapour line. This line carries vapour at low pressure and has a much larger diameter to suit.
Where the tank valves are located in an enclosed space, like the boot of a car, a containment hose of plastic is used to provide a gas-tight seal between the gas components and the inside of the vehicle.
Liquid hoses are specifically designed and rated for the pressures that exist in Autogas systems. These hoses are made from materials designed to be compatible with the fuel.
Some hoses are made with crimped fittings, while others are made using re-usable fittings that are pressed or screwed onto the end of the hose.
Rigid sections of liquid line are usually made using copper tubing, although in some applications, steel pipes are used instead. The ends of the pipes are always double-flared and fitted with flare nuts to secure them to the fittings.
Liquid line fittings are mostly made from brass. The fittings typically adapt from a thread in a component, such as a (British Standard Price Thread) or NPT (National Pipe Thread - US) threaded hole on a tank, to an SAE (PLEASE EXPLAIN THIS ONE) flare fitting to suit the ends of pipes or hoses
Tanks
Vehicles are often fitted with one tank, but multiple tanks are used in some applications. EXAMPLE
All tanks have various fittings like filling, liquid outlet, emergency relief of excess pressure, fuel level gauge and sometimes a vapour outlet. These may be separate valves mounted into a series of 3 to 5 holes in a plate welded into the tank shell, or may be assembled onto a multi-valve unit which is fitted into one large hole on a boss welded into the tank shell.
Today's fill valves are usually fitted with an Automatic Fill Limiter (AFL) to prevent overfilling. The AFL has a float arm which restricts the flow of fuel but does not shut it off entirely. This causes the pressure in the line to rise enough to indicate during refilling to the pump to stop pumping.
The liquid outlet is used to supply fuel to the engine, and is usually referred to as the service valve. Modern service valves incorporate an electric shutoff solenoid. In applications using very small engines such as small generators, vapour may be withdrawn from the top of the tank instead of liquid from the bottom of the tank.
The emergency pressure relief valve in the tank is called a hydrostatic pressure relief valve. It is designed to open if the pressure in the tank is dangerously high, thus releasing some vapour to the atmosphere to reduce the pressure in the tank. The release of a small quantity of vapour reduces the pressure in the tank, which causes some of the liquid in the tank to vapourise to re-establish a balance between liquid and vapour. The latent heat of vapourisation causes the tank to cool, which reduces pressure even further.
The gauge sender is usually a magnetically coupled arrangement, with a float arm inside the tank rotating a magnet, which rotates an external gauge. The external gauge is usually readable directly, and most also incorporate an electronic sender to operate the fuel gauge on the dashboard.
Valves
Many different types of valves are used in Autogas systems. The most common ones are shutoff or filterlock valves. These valves are used to stop the flow in the service line and are operated either by vacuum or through electricity. When using a dual-fuel systems (petrol carburettor and Autogas), a similar shutoff valve is usually fitted in the petrol line between the pump and carburettor.
In order to allow fuel to flow in one direction, check valves are fitted in the filler and on the fill input to the fuel tank. Service valves are fitted to the outlet from the tank to the service line. These have a tap that allows to turn the fuel on and off. The tap is usually only closed when the tank is being worked on. In some countries, an electrical shutoff valve is built into the service valve.
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Where multiple tanks are fitted, a combination of check valves and a hydrostatic relief valve are usually installed to prevent fuel from flowing from one tank to another.
Converters
A converter or vaporiser is a device designed to change fuel from a state of being a pressurised liquid to a vapour at atmospheric pressure in order to deliver to the mixer or vapour phase injectors.
Due to the cooling characteristic of the fuel, heat is put into the fuel by the converter. This is usually achieved by having an engine coolant circulated through a heat exchanger that transfers heat from that coolant to the Autogas.
There are two distinctly different basic types of converters for use with mixer type systems.
The European style of converter is a more complex device that incorporates an idle circuit and is designed to be used with a simple fixed venturi mixer. The American style of converter is a simpler design which is intended to be used with a variable venturi mixer that incorporates an idle circuit.
Engines with a low power output such as; scooters, quad bikes and generators can use a simpler type of converter (also known as governor or regulator). These converters are fed with fuel in vapour form. Evaporation takes place in the tank where refrigeration occurs as the liquid fuel boils. The tanks large surface area exposed to the ambient air temperature combined with the low power output (fuel requirement) of the engine make this type of system viable. The refrigeration of the fuel tank is proportional to fuel demand hence this setup is only used on smaller engines. This type of converter can either fed with vapour at tank pressure (called a 2 stage regulator) or be fed via a tank mounted regulator at a fixed reduced pressure (called a single stage regulator).
Mixer
A mixer is a device that mixes the fuel into the air flowing into the engine. Mixer type systems have existed since the 1940s and are now being increasingly superseded by injectors.
