ATEX - Burner Unit - Hazardous Area Zoning

Situation:

Natural gas is used as fuel for a burner unit in a powder flash drying process within a building. This gas pipework has flanges, joints, electricals, fittings, etc. 

Task:

To minimise the potential for the formation of flammable atmospheres (external and internal within the burner unit)

Typical Natural gas pipework feeding into a burner unit

 

Action (Solution): 

Within the burner unit

An appropriate burner management system should have the following:

1. Should shut off the fuel supply on flame failure and on loss of combustion air. 
2. Should incorporate an air purge sequence, which ensures that any residual flammable gas is purged from the burner unit before it is relit.

External to the burner unit:

The following can be undertaken: 

1. Provide ventilation to the area. This could be achieved by forced (mechanical) or natural ventilation by installing louvres or other openings in a manner to provide a cross flow of air over the equipment, where leaks may occur.
2. Install a gas detection system. Detectors could be installed to identify a leak of flammable materials, and alert users to the leak. This system could be linked to a means of isolating heating and flow of materials into the system. 

Result:

As a result, there would be no requirement for hazardous area classification around the gas supply pipework, as the alarm would be set to activate at a small proportion of the lower explosive limit of the gas released, say 20% LEL, which would ensure that no flammable atmospheres may be generated. Regular natural gas detection leak checks should be conducted as a part of a preventive maintenance program as an additional control measure or adequate ventilation to dilute the vapour