LTRM;
Use a length of 5/16 dia. clear plastic tubing bent in the form of a U tube with a tape measure sandwiched in the center and you now have a water column guage. N. Am. is an abbreviation for North American market (USA, Canada and Mexico), while EC the standing abbreviation for European Common market built trucks.
I would hesitate trying to use the power adjustment mixture to compensate for incorrect metering orfices and secondary spring in a vaporizer - regulator because of balance over a wide operating range. Main LPG components between the markets are engineered to match and compliment each other. With the addition of engine management systems for large spark ignited engines in the US market falling under EPA regulation one could find one's self in a gray area that could lead to some healthy fines. Keep in mind the way the wording of the regulations are that any changes regarding safety must have written approval from the manufacturer. The UL label is what you are in conflict with also.
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