TM 5-4220-227-14 1-6.  List of Abbreviations. AC alternating current AF Audio Frequency AMDF Army Management Data File AMPS Ampere(s) BATT Battery BIBS Built in Breathing System CCU Chamber Conditioning Unit CO₂ Carbon Dioxide DC Direct Current FSW Feet of Sea Water ft Feet GFI Ground Fault Interrupter GPM Gallon Per Minute hex Hexagonal HP Horse Power in. Inch I/L Inner Lock IA Isopropyl Alcohol ID Inside Diameter Kpa Kilopascal lb(s) Pound(s) LPM Liter Per Minute M/L Medical Lock MAP Military Assistance Program MED Medium MIC Microphone ml Mili-liter MOS Military Occupational Specialty NID Non-ionic detergent N.P.T. National Pipe Thread O/L Outer Lock 0₂ Oxygen OD Outside Diameter pH Hydrogen Power POA Portable Oxygen Analyzer POMCUS Preposition of Material Configured to Unit Sets psi Pounds Per Square Inch psig Pounds Per Square Inch Gage SCF Standard Cubic Feet SCFM Standard Cubic Feet per Minute SIMS Selected Management System TSP Trosodium Phosphate VAC Volt, Alternating Current VDC Volts Direct Current Plus or Minus (as in 90°  or 30)-Degree(s) 5F Degree(s) Fahrenheit % Percent 1-2