MI-04 N-2001 Regulator/Converter After passing through the electric fuel lock-off, liquid propane enters the N-2001 regulator/converter (Figure 13). The N-2001 functions as a fuel vaporizer, converting liquid propane to vapor propane and as a two-stage negative pressure regulator, supplying the correct vapor propane fuel pressure to the mixer. The regulator is normally closed requiring a vacuum signal (negative pressure) to allow fuel to flow. This is the second of three safety locks in the MI-04 system. If the engine stops, vacuum signal stops and fuel flow will automatically stop when both the secondary (2 nd stage) valve and the primary (1 st stage) valve closes.
Unlike most other regulator/converters, the N-2001 primary valve closes with fuel pressure rather than against pressure, extending primary seat life and adding additional safety. Liquid propane must be converted into a gaseous form in order to be used as a fuel for the engine. When the regulator receives the desired vacuum signal it allows propane to flow to the mixer. As the propane flows through the regulator the pressure is reduced in two stages from tank pressure to slightly less than atmospheric pressure.
As the pressure of the propane is reduced the liquid propane vaporizes and refrigeration occurs inside the regulator due to the large temperature drop inside the regulator from the vaporization of liquid propane. To replace heat lost to vaporization, engine coolant is supplied by the engine driven water pump and pumped through the regulator. Heat provided by this coolant is transferred through to the fuel vaporization chamber. (Figure 14) shows the heat chamber and the coolant passage in the N-2001. N-2001 Heat Transfer Chamber Coolant Passage Figure 14 Figure 13 G420E/G424E Tier LP Engine System Operational Overview 18