Proportional valves


Thread Starter


I'm new to this list, and was hoping for some advice on this. I've got this project in school, converting a gasoline engine to run on natural
gas. So far I've got a controller board for the closed loop control of the air fuel ratio. The output is a varying signal from 0 to 5V. The biggest problem now is because i have to use mains gas supply as the fuel source, it only has a pressure of 18mbar gauge(7" water). Normal gas injectors do not work at that low pressure and i have to find alternative means for fuel metering. so far one solution i have found are proportional flow control solenoid valves. The natural gas flow rate needed to sustain engine operation is somewhere around 500L/min. This means i have to find a pretty large proportional valve for it, which becomes costly and most companies do not stock large valves anyway Is there any other way of providing a proportional flow to the engine,
varying according to my input signal? The valves also have to be normally closed with no exhaust ports as regulations prevent exhausting
of the gas into the environment. I'm trying to avoid carburettors as this is supposed to be an exercise in control of the air/fuel ratio, along with possibilites of lean burn.