After field use, the dry gas meter and rotary meter were checked at an intermediate flow rate of approximately 60% of rated flow. If the calibration values have changed less than 1.5%, the field data are acceptable. If a change from the previous calibration values is more than 1.5%, the meter will be recalibrated over its full range of flow.
Temperature and pressure transmitters used for field measurements were calibrated after testing. Calibration data forms for the rotary meter, thermocouple, and pressure transmitters are shown in Appendix C.
4.3 Analysis Procedure
Prior to initiating the emissions test, all vapor fittings on the processor were leak tested. The test lasted 72 hours. Two approximate 24 hour periods were without the PERMEATOR® operating. One of these 24 hours was with the pressure vacuum (PV) valve removed from the vent pipe and the second 24 hour period was with the PV valve attached to the vent pipe. During these two time frames only the outlet analyzer and flow were monitored. The third 24 hour period was while the PERMEATOR® is in operation and the inlet and outlet hydrocarbon concentrations were continuously recorded. The analyzers were zero and span checked about once every six hours. The average volume meter temperatures and pressures, during each one minute interval, were logged by the DAS and used to convert actual meter volume to standard conditions.
During the test period gasoline dispensing data will be gathered from the computers logging the gasoline loading data.
4.4 Data Analysis
The hydrocarbon analyzer readings were averaged by the DAS over each one minute interval. The vapor volumes were obtained by totaling the number of pulses over each one minute period. The volumes were then converted to standard conditions using the recorded temperature and pressures.
Inlet and return volumes were calculated from outlet composition using the formulas described in Method 2B which are included in the next section. The outlet mass was then calculated as the product of outlet volume, pollutant concentration and the standard density of the pollutant. The pounds per 1000 gallons dispensed rating was calculated by dividing the total hydrocarbon mass emitted by the amount of gasoline dispensed.
