Hands-Free Lighting

The Hazloc standard - Explosive environments 

Explosive Atex enviroments

Under what conditions can an explosion occur?
A risk of explosion becomes possible when several elements are present, examples below:

  • Oxidant: Oxygen present in the air
  • Fuel:

    gas vapours: solvents, dilutants, hydrocarbons, varnishes, perfumes, dyes, alcohol, gas, chemical products, etc.
    dust and powders: flour, sulfur, carbon, magnesium, aluminium, milk, resins, starch, cellulose, sugar, etc.
    a source of combustion or 'hot spot'

For example, when a flour mill is in operation the concentration of dust is very high. A highly dusty atmosphere is very dangerous, a spark or even a rise in temperature could cause an explosion.

When the risk of explosion has been identified in a given environment, a safety requirement relating to equipment will be imposed. The equipment used must be designed to specifically diminish the risk of explosion. For example, ATEX head torches may be required.

The HAZLOC standard
What is HAZLOC?
HAZLOC primarily concerns North America. HAZLOC aims to control the risk of explosion for certain environments. HAZLOC certification consists of two elements:
  • factory inspections
  • testing and evaluation of products

Choosing equipment adapted for use in an explosion risk environment
Locations that are hazardous are classified in three ways under the HAZLOC standard:

  • by conditions
  • by nature of the hazardous substance or material
Hazardous environment types (divided into three classes):
  • -Class I: a space that has become dangerous due to the presence, or possible presence of vapour or gases in sufficient quantity to be flammable or explosive. Examples could include spray finishing zones, petroleum refineries, etc.
  • -Class II: a space which due to the presence of flammable air-borne dust has become dangerous. Examples could include fireworks factories, grain silos, flour mills etc.
  • Class III: a space where air-borne fibres and particles can deposit on or around machines, lighting equipment etc where they could be ignited by heat, sparks or hot metal. Conditions
  • -Division 1 (average conditions): the risk is present during normal production operations or on going maintenance and repairs.
  • -Division 2 (unusual conditions): dangerous substances only present in the event of defective functions or accidental breakages. Nature of the hazardous material or substance
  • Gases and or vapours falling within Class I are divided into four groups: A,B,C,D (groups are assigned according to the combustion temperature, explosion pressure and other combustion characteristics).
  • Dangerous substances within Class II hazardous environments are divided into three groups: E,F,G (groups are assigned according to their relevant combustion temperature and conductivity).

Classes

Groups Divisions

1

2

I Gases, vapors, liquids

A: Acetylene
B: Hydrogen, etc.
C: Ether, etc.
D: Hydrocarbons, fuels, solvents, etc.

Explosive and always dangerous

Normally not present in quantities sufficient for explosion (but this situation may accidentally arise)

II Dust

E: Metal dusts (conductive and explosive)
F: Carbon dusts (some are conductive and all are explosive)
G: Flour, starch, grain, combustible plastic or chemical dusts (explosive)

The quantity of dust is sufficient to be flammable, or the dust is conductive under normal conditions.

Normally not present in quantities sufficient for explosion (but this situation may accidentally arise)

III Air-borne fibers and particles

Textiles, wood debris, etc.

Manipulated or used during manufacture

Stored or manipulated in a storage area (away from manufacturing)

What specific features to certified headlamps have?
The higher the level of protection required the less powerful the lighting will be. Voltage and intensity levels permitted may be low to ensure the device will not produce sparks, dangerous temperatures or an electrical arc.

HAZLOC example marking:
-the marking: FLASHLIGHT FOR USE IN HAZ. LOC.
-marking details: CLASS I, DIV 2 GROUPS C, D, CLASS II, DIV 2 GROUP G

Class I: gaseous environments:
-Class I
= gas
-Class II = dust
-Class III = fibers
Div 2 = type of conditions:
-Div 1: present under normal conditions
-Div 2: present under abnormal conditions
GROUPS C and D: corresponds to the classes of gas covered by the product
Class II: dusty environment
Div 2: present under abnormal conditions
GROUP G: corresponds to the classes of dust covered by the product