Shippers are encouraged to make appropriate calculations before They are also encouraged to read the provisions of these exceptions carefully before transporting aerosols intended for disposal or recycling. June 2017 SPRAY 31 attempting to take advantage of these provisions. the drum must be compatible with the hazardous material; and • The pressure inside each completed drum, at any time during transportation, may not exceed the design test pressure marked on the drum. The pressure requirement within the drum poses some unique challenges in that these drums are authorized for aerosols that may be leaking. Assuming that there is pressure in the aerosols when packaged in the transport drums, the shipper would have to calculate the maximum pressure that could be encountered in transit, a task not easily done. For example, if a waste lot of 10 fl oz (296mL) DOT specification 2P aerosols having a static charge pressure of 10 bar (~150 psi) are to be transported in a UN steel 1A2 drum tested to a hydrostatic test pressure of 200 kPa (2 bar), the limiting number of aerosols would have to be calculated so that the maximum hydrostatic pressure is not exceeded. Using the ideal gas law (shown below), the pressure inside the drum could be estimated as follows: PV = nRT P = pressure, V = volume, nR = a constant, and T = temperature Assuming the temperature remains constant, the change in volume or pressure can be calculated using the following formula: P1V1 = P2V2 Therefore, using the previous example… 2 bar x 200L = 10 bar x 0.296L x N (where N = the limiting number of aerosol cans). In this case, N would be = 2 bar x 200 L / 10 bar x 0.296 or N = 135 cans. Therefore, it would important to know the pressure inside the receptacles when placed into the drum and the drum particulars. If the pressure is unknown, one would have to assume the highest pressure for the aerosol can (e.g., 180 psi for a DOT specification 2Q). Shippers are encouraged to make appropriate calculations before attempting to take advantage of these provisions. They are also encouraged to read the provisions of these exceptions carefully before transporting aerosols intended for disposal or recycling. Questions regarding the management of aerosols intended for disposal or recycling can be directed to the Pipeline & Hazardous Materials Safety Administration (PHMSA) at (202) 467-8922 or ShipMate, Inc. at (310) 370-3600. SPRAY
Spray June 2017
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