Appendix A: Procedure - Liquefied Petroleum Gas Tank Car Emission Standard

A1. Tester

A1.1 This procedure utilizes a portable combustible gas tester for the measurement of hydrocarbon concentration in air and expresses the values as a percentage of the lower explosive limit (% LEL). These measurements must be taken within the protective housing of the Liquefied Petroleum Gas (LPG) tank car.

A2. Method

A2.1 A gaseous sample is withdrawn from the protective housing of the LPG tank car at standardized conditions and analyzed by a portable combustible gas detector. The results obtained as a percentage of the lower explosive limit relate to the concentration of hydrocarbons in the protective housing.

A3. Apparatus

A3.1 A portable combustible gas detector suitable for % LEL measurements with a resolution of at least 1% LEL in the 0% to 10% LEL range and at least 2% LEL in the 10% to 100% LEL range. The accuracy of the detector must be at least ± 5% of the full range in both ranges. The detector must be intrinsically safe. The probe must be made of non-sparking materials or fully covered by insulating materials. The tube between the probe and the detector must be made of material compatible with LPG, shall not interfere with LEL measurements, and must be equal to or less than 100 cm (39 in.) in length.

A4. Calibration

A4.1 The procedures for verification of calibration of the detector must be in accordance with the instructions and recommendations of the supplier of the instrument. Verification of the calibration of the detector using an appropriate gas mixture must be performed:

  1. at least once a week, if the detector is used daily; and
  2. before use, if the detector is not used daily.

A5. Measurements and Acceptance Criteria

A5.1 The % LEL measurements must be performed, the results evaluated, and the corrective actions taken as necessary in accordance with the following requirements:

A5.1.1 Measurements — The gas samples must be taken within the protective housing of the LPG tank car. The protective housing cover, portholes, and flaps must have been closed for a minimum of 10 min before taking the sample. When possible the sampling probe must be in a horizontal position, resting on the lower edge of the porthole, and the tip of the probe must be inserted approximately 30 cm (12 in.) inside the protective housing. The sampling and measurement methods must be in accordance with the instructions and recommendations of the supplier of the instrument.

A5.1.2 Definition of Leaking — The LPG tank car is leaking if:

  1. emissions originating from the reclosing pressure-relief device or the joint between the manway nozzle and manway cover can be detected; or
  2. the measurements taken in accordance with the procedures set out in clause A5.1.3 do not establish that the tank car is not leaking.

A5.1.3 Procedures — The measurement of % LEL inside the protective housing of the LPG tank car must be made in accordance with the requirements set out in clause A5.1.1.

  1. If the initial measurement is equal to or less than 10% LEL, the tank car is deemed not to be leaking and no further action is required;
  2. If the initial measurement is greater than 10% LEL, the protective housing must be opened and thoroughly vented and a second measurement must be performed. If this second measurement is equal to or less than 10% LEL and the initial measurement was equal to or less than 12% LEL, the tank car is deemed not to be leaking and no further action is required;
  3. If the second measurement differs by more than 2% LEL from the initial measurement, a third measurement must be performed from another porthole. If this third measurement is equal to or less than 10% LEL, the tank car is deemed not to be leaking and no further action is required.

A5.1.4 Corrective Action — If the LPG tank car is leaking, the source of the emissions must be investigated and corrective action must be taken to stop or reduce the leaking.

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