B-1.1, r. 2 - Construction Code

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8.95. The tank of a petroleum equipment installation installed during construction work must have a vent.
The vent may not be connected to more than one tank unless it is of a diameter that allows the vapours from the various tanks to be purged without causing the allowable stress for each tank to be exceeded.
The vent on a tank that is to contain a Class 1 petroleum product may not be connected to the vent of a tank that is to contain a Class 2 or Class 3 petroleum product.
O.C. 220-2007, s. 1.