PV OFF - Vent stack test with pressure/vacuum relief valve removed
PV ON - Vent stack test with pressure/vacuum relief valve installed
Open - measurements taken while the station was open for business (active refueling)
Closed - measurements taken while the station was not open for business (no refueling)
Pulses - pulses counted by Matus Tech Services data logger. For PV OFF, each pulse corresponds to 0.5 ft3 of flow and for the PV ON test, each pulse corresponds to 0.25 ft3 of flow. Different correlation for different meters used.
%HC (% of hydrocarbons) - average hydrocarbon concentration (measured as C3H8, propane) volume % in the exhaust vapor (measured by sensors at test site)
Avg Temp (Average Temperature) - average temperature of the exhausted vapor (measured)
Ft3 (cubic feet) - corrected volume (scf - standard cubic feet) from measured (acf- actual cubic feet) based on temperature and pressure conditions (measured by sensors at test site)
Mg of C3H8 (milligrams of hydrocarbons) - milligrams of hydrocarbon measured as propane (C3H8)
Lbm (pounds) - conversion of milligrams to pounds as propane, C3H8
Mass gasoline - propane (C3H8) mass is converted to pounds of gasoline by using the ratio of the molecular weight (MW) of gasoline vapor (MW = 66) to the molecular weight of propane (MW = 44) Example: 66.84 lbm * 66/44 = 100.26
Gallons liquid - gasoline liquid volume is calculated by dividing the mass of gasoline by 5.2 lbm/gallon liquid conversion factor. Example: 100.26 Mass Gasoline / 5.2 (pounds of gasoline per gallon of liquid gasoline) = 19.28
Gallons liquid/day - test period interval is extrapolated to account for a total of 24 hours per day Example: 19.28 Gallons Liquid / 1,303 minutes in test interval * 60 minutes per hour * 24 hours = 21.31 gasoline gallons saved per day
% Throughput - the gasoline gallons saved per day (gallons liquid/day) are divided by the gallons dispensed for the 24-hour period to yield a % of throughput figure. Example: 21.31 gallons liquid saved per day / 19,186 gallons of daily throughput = 0.111%
cfm (cubic feet per minute) - the average cubic feet (ft3) of vapor volume per minute during Station Open and Closed periods is tabulated by dividing the ft3 column entry by the time interval during the data collection period
lbm/hr (pounds of gasoline exhausted per hour) - the pounds per hour figures are tabulated by dividing the mass of gasoline entries by the time interval during the data collection period. Example: 1,450.57 ft3 / 1,303 minutes of test interval = 1.113 cubic feet per minute (cfm)
lbm/1,000 gal - the pounds of gasoline vapor emitted per 1,000 gallons of gasoline dispensed figures are calculated by converting the gallons liquid per day to pounds by multiplying by 5.2 lbm/gallon and then dividing by the daily throughput x 1,000. Example: 21.31 gallons per day saved * 5.2 pounds per gallon / 19,186 gallons of daily throughput * 1,000 gallons = 5.776 lbm/1,000 gallons