Reduction in the Release of Volatile Organic Compounds (Storage and Loading of Volatile Petroleum Liquids) Regulations (SOR/2025-88)

Control Conditions

• 1 The control conditions to be used when measuring the seal gaps of a floating roof tank are as follows:

  • (a) a set of uniform cylindrical probes of varying diameters that meet the following criteria must be used:

    • (i) the smallest probe must have a diameter of 0.3 cm,

    • (ii) one of the probes must have a diameter of 4 cm if a primary seal gap is being measured or a diameter of 1.3 cm if a secondary seal gap is being measured, and

    • (iii) each probe must have a diameter that is less than double the diameter of the next smallest probe;

  • (b) the liquid level in the tank must not change;

  • (c) if the tank is an external floating roof tank, all seal gap measurements must be taken while the floating roof is freely floating on the surface of the liquid and not when it is resting on a support structure or suspension system; and

  • (d) if a primary seal gap is being measured, any secondary seal or cover that restricts access to the primary seal must be pulled away from the tank wall, removed or otherwise positioned such that it will not interfere with the measurement.

Procedure

• 2 The procedure to be followed to measure the seal gaps of a floating roof tank consists of the following steps taken in the following order:

  • (a) identify all seal gaps on the circumference of the tank by passing a probe that has a diameter of 0.3 cm between the seal and the wall of the tank without forcing or binding the probe against the seal;

  • (b) determine the length of each seal gap by measuring, in centimetres, the circumferential distance along the tank wall between the two extreme opposite ends of the seal gap;

  • (c) determine the surface area of each seal gap by using successively larger probes to measure, in centimetres, the width of the gap between the seal and the wall of the tank and then multiplying each width by its respective length determined under paragraph (b) (if the width of the seal gap at any point is larger than the diameter of one probe but smaller than the diameter of the next probe, then the width must be linearly interpolated using the measurements of those two probes);

  • (d) determine and record the width of the widest seal gap;

  • (e) calculate the sum of the individual surface areas determined under paragraph (c) for all seal gaps identified under paragraph (a); and

  • (f) divide the total surface area determined under paragraph (e) by the inside diameter of the tank and record the result in cm² per m.

Other Instruments

• 3 Despite paragraphs 1(a) and 2(c), an instrument with a single probe not larger than 0.3 cm may be used to measure the seal gaps if it can measure gaps ranging in size from 0.3 cm to 4 cm with a margin of error less than half the diameter of the seal gap.