Hazardous Area Trace Heating

What is an explosive atmosphere?

An explosive atmosphere location is defined as a place

where concentrations of flammable gases, vapors, or

dusts occur. If there is enough of the substance, mixed

with air, any source of ignition could cause an explosion.

Explosions could lead to loss of life and serious injuries

as well as significant damage and expense. Preventing

the concentrations of dangerous substances, which

create an explosive atmosphere, and preventing the

ignition source are the two most commonly used ways to

reducing the risk.

All electrical equipment that must be installed in hazardous

locations are specifically designed and tested to ensure it does

not initiate an explosion, due to arcing contacts or high surface

temperature of equipment.

What is a stabilised design?

A stabilised system is where the power loading of the trace heating tape is such that under conditions of no

temperature control i.e. thermostat failure, the sheath temperature of the tape cannot exceed the ‘T’

classification.

Ideally all heat trace systems should be designed to be stabilised systems.

Where stabilised designs cannot be achieved it is

necessary to employ an over-ride thermostat with

lockout and alarm facility to prevent the ‘T’

classification being exceeded.

NOTE: non-stabilised designs may lead to

operational problems as the over-ride thermostat

may prevent the electric trace heating system

delivering the required heat output (kWhr) under

low ambient temperature conditions. It is therefore

essential that the thermal design characteristics of

the system are carefully evaluated.

Hazardous areas…

* Zone 0 * An area or enclosed space within any

flammable or explosive substance, whether as, vapour,

or volatile liquid, is continuously present in

concentrations within the lower and upper limit

flammability.

* Zone 1 * An area in which any flammable or explosive

substance, whether gas, vapour or volatile liquid, is

processed, handled, or stored, and is likely to occur in

sufficient quantities to produce a hazard.

* Zone 2 * An area in which any flammable or explosive

substance, whether gas, vapour or volatile liquid

although processed or stored, is so well under conditions

of control that the production or release of an explosive

or ignitable concentrate in sufficient quantity to constitute

a hazard is only likely under abnormal conditions.

As an ATEX Certified Company, ESH Trace Heating Ltd hold approvals for the manufacture and installation of explosive atmosphere trace heating solutions.