Which statement correctly describes the units used for the JP5 DFWD and JP5 CFD limits?

• A. Both limits are expressed in ppm
• B. JP5 DFWD uses ppm and JP5 CFD uses mg/L
• C. Both limits are expressed in mg/L
• D. JP5 DFWD uses mg/L and JP5 CFD uses ppm

Answer: (B)

Concentration limits in JP5 testing come in different units because the measurement methods define the unit they report. JP5 DFWD uses ppm because it expresses dissolved water concentration as a ratio within the fuel, a common way to report contaminants in hydrocarbons. JP5 CFD uses mg/L because it measures the mass of water per liter of fuel under a specific test condition. Remember that ppm and mg/L aren’t automatically interchangeable in fuels, since density differences matter; converting would require the fuel’s density and the exact ppm definition used. Read the limits as stated: DFWD in ppm and CFD in mg/L.