OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 10 Fire and Explosion Hazards

Section 168 Industrial furnaces and fired heaters

Subsections 168(1) and 168(2)

The employer must take measures to ensure that gas and oil-fired furnaces do not explode. If a furnace is being used to heat a flammable substance other than its fuel, the fuel supplying the furnace’s heating system must not mix with the flammable substance that is being heated. The two systems must function independently – inserted blinds or double block and bleed systems are not acceptable methods of isolation.

Subsection 168(3)

No explanation required

Subsections 168(4) and 168(5)

For information about Zones and Divisions as classified under the CEC, readers are referred to the explanation for section 162.

While prohibited outright for Division 1, Zone 0 or Zone 1 classified areas, a furnace or fired heater may be located and operated in a Division 2 or Zone 2 classified area if:

(a) the combustion mechanism of a furnace or heater is located within an enclosure that completely separates it from the external environment. Only the air intake and the exhaust discharge may protrude but there should be an adequate seal placed around these to prevent the return of stray emissions. This helps prevent stray emissions of explosive substances from reaching the ignition component of the furnace or heater;

(b) flammable substances are prevented from igniting on any surface of the furnace or heater that may be exposed to atmosphere. This can be accomplished by

(i) ensuring that the furnace or heater is operated in such a way that the temperature of the exposed surface is below the ignition temperature range of the flammable substances that may be on the site,
(ii) preventing contact by placing barriers or blanketing material between the surface and the flammable substance;

(c) a flame arrestor is placed in the air intake and the discharge of the furnace or the heater, or, alternatively, the intake and discharge mechanisms are extended beyond the boundaries of the hazardous location.

Subsection 168(6)

If it is not reasonably practicable to ensure that flammable substances do not ignite on the surface of the furnace or heater [in accordance with subsection 168(5)], other effective means must be used to prevent ignition.