|The Board of Transport
Commissioners for Canada
|Commission des Transports
Order no. G.O. 591
|Saturday, the 2nd of
September, A.D. 1939
In the matter of the consideration of the question of proposed regulations with regard to recommended practice for the prevention of electric sparks that may cause fire during the transfer of inflammable liquid between units of equipment operated on rails or between equipment operated on rails and wayside piping, pumps, tanks, or other structures.
F. N. Garceau
J. A. Stoneman
G. A. Stone
Upon the report and recommendation of the Chief Engineer of the Board—
It is ordered that the following regulations with regard to recommended practice for the prevention of electric sparks that may cause fire during the transfer of inflammable liquid between units of equipment operated on rails, or between equipment operated on rails and wayside piping, pumps, tanks, or other structures, be, and they are hereby, authorized for the observance of railway companies subject to the jurisdiction of the Board, namely:—
(For the purpose of these rules, an inflammable liquid is one so defined by the Orders of the Board of Transport Commissioners.)
The connection through which the liquid is carried may be either metallic or non-metallic. If the connection is not permanent, the terminal connections shall be made from a non-ferrous metal softer than iron.
A permanent electrical connection with a stranded cable having a mechanical strength not less than that of No. (AWG) copper cable and conductivity not less than that of No. 4 (AWG) copper should be made between the rails on which the rail equipment stands and the other rail equipment or the wayside facilities involved in the transfer operation. This connection may be accomplished in one of two ways:—
In addition to the requirements under clauses 1 and 2, an adequate return conductor,, independent of the rails, should be installed from the rails of the insulated track section to the rails of the main track through a return switch which, when closed, short circuits the insulating joints. This return switch should be inter-locked with a two-way switch controlling the supply of propulsion power to the contact conductor of the insulated track section in such a way that the contact conductor is normally dead and grounded and the return switch normally open. The ground for the contact conductor should be metallically connected to the ground for the rails of the insulated track section.
Other measures may be used as may be necessary w4iere extreme conditions exist, such as electrical^ inter-connecting a paralleling pipe system or other metallic structures and grounding them.
Where tracks which are electrified are supplied from an electric system which might introduce values of short circuit currents at the transfer tracks that would set up differences of potential of a hazardous magnitude, it is recommended that special studies be made by qualified persons and such additional or substitute measures taken as are necessary to provide adequate protection.
Note (a).—During transfer operations where rail equipment is on an insulated section of track, caution must be exercised against the bridging of the insulated joints by movement of either rail equipment or any other agency.
Note (b).—Where rail equipment is insulated from the rails by rubbertired wheels, body insulation, rusty or dirty rails, or other causes, a flexible electrical conductor shall be used of not less than No. 6 copper (AWG) conductivity and strength which shall be permanently grounded—the free end being provided with a clamp which shall be made fast to a bright spot on the tank car before the flow of liquid is started and remain there until the flow has ceased.
The Board of Transport Commissioners for Canada.