TM 10-6640-239-13 1-6 1-8. NOMENCLATURE CROSS-REFERENCE LIST. Common Name or Abbreviation Official Nomenclature Modular Base Petroleum Laboratory (MBPL) Petroleum Laboratory, Semi-Trailer Mounted Gas Alarm Gas Detection and Alarm System ASTM American Society for Testing and Materials FTMS Federal Test Methods Standards ECU Environmental Control Unit LCD Liquid Crystal Display Hg Mercury Hz Hertz V Volts psi Pounds per Square Inch amp Ampere W Watt RPM Revolution per Minute AC Alternating Current DC Direct Current lel Lower Explosive Limit Steam Super Heater High Pressure Boiler Steam Generator Low Pressure Boiler hp Horsepower pH Degree of Acidity or Alkalinity gph or GPH Gallons per Hour gpm or GPM Gallons per Minute %V Percent of Volume GFI Ground Fault Interrupt A Lab Petroleum Laboratory, Model-A B Lab Supplemental Petroleum Laboratory, Model-B