Hazardous Location Equipment

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The HazLoc Equipment Process.

When electrical equipment needs to be operated in a hazardous location (HazLoc), a series of steps must be followed in order to ensure due diligence and compliance with local laws.

While there can be local jurisdictional differences in how HazLoc equipment is deemed approved for use, the general process is summarized by the 5 steps below:

• Identify the hazardous dust or vapour and categorize the explosion hazard.
• Evaluate all hazards presented by the equipment which is the subject for the HazLoc evaluation.
• Determine if all hazards on the electrical equipment are controlled using acceptable “protection methods”.
• Complete the formal equipment approval, with a nationally recognized Certification Agency such as Attesta, CSA, UL, etc.
• Ensure proper intra-company distribution of all documents integral to the hazloc approval and train all users on their importance and any noted conditions of acceptability.

Process Step 1:

Every HazLoc equipment evaluation depends on a proper assessment of the presence of the hazardous substance that is the cause of the explosion hazard.  A key determination is also whether the hazardous substance is present in the ambient environment of the equipment, or whether the equipment itself is the source of the substance.

The determination of whether a hazardous substance is present in sufficient concentrations to merit concern of an explosion hazard depends on many factors.  Some of these include:

• The quantity of the substance present at any given time
• The ability of the substance to accumulate on surfaces over time
• Ventilation
• Temperature of the equipment
• Flammability rating of the substance
• Probability of a failure of equipment which could disperse the substance in an unfavourable manner

An assessment of the risk of explosion is the result of a comprehensive risk analysis which utilizes empirical data on the properties of individual substances as well as guidance provided in nationally recognized codes and standards related to specific applications.

The result of the assessment is generally one of the following:

1. the application is deemed to be non-hazardous (ordinary)
2. the application is deemed to be hazardous (HazLoc) with a single HazLoc zone rating applicable to the entire equipment
3. the application is deemed to be hazardous (HazLoc) with multiple HazLoc zone ratings associated with different sections of the equipment

For case 1 above, a formal document should be issued by a competent entity (generally a professional engineering firm) to document the rationale and resultant determination.

For case 2 or 3, a formal document, in the form of a Hazardous Area Classification document should be issued by the competent entity to identify the following:

• designated area classification which includes a Class/Div or Zone
• identification of the substance(s) of concern
• Temperature Code
• Group Code for the substance (ie:  Gas Group, or Dust Group)
• Boundaries, as applicable for all classified zones involved
• Any critical assumptions used in the determination

Process Step 2:

This step is generally part of the scope of an accredited Certification Agency such as Attesta, UL, or CSA. 

The evaluation of explosion hazards related to a piece of equipment is generally initiated with the assumption that there are no protection methods in place.  This evaluation is best done at the design stage (to avoid possible retrofit costs), however it can be done even after a system is completely built.

Equipment explosion hazards can stem from such things as:

• Sparks or arcs from electrical circuits and devices
• Sparks from static charges
• Sparks from mechanical devices
• High temperature surfaces

Process Step 3:

This step is generally a continuation of the scope of an accredited Certification Agency such as Attesta, UL, or CSA.

Every hazard identified in Step 2 above needs to be addressed to effectively to mitigate the risk of an explosion.  Every hazard mitigation method needs to meet the requirements of recognized standards related to equipment in explosive atmospheres (see 60079 series of UL or CSA standards). 

For hazards that are not related to sparks or arcs from electrical circuits and devices, the only solution to address the hazard is elimination of the hazard, sometimes with engineering methods.

For hazards that are not related to sparks or arcs from electrical circuits and devices, the only solution to address the hazard is elimination of the hazard, sometimes with engineering methods.

Some of the more commonly utilized protection methods are:

• Intrinsic Safety
• Explosion Proof (also called Flameproof)
• Non Incendive
• Increased Safetty
• Purging and Pressurization
• Encapsulation
• Dust-tight

Process Step 4:

This step involves a comprehensive review of all requirements related to the standards against which the equipment is being certified.  Every clause of the pertinent standard is verified in what is known as a construction checklist.

In addition, not only are all protection methods in the previous step verified for compliance, but the manner in which the protection methods are incorporated are verified for correctness, accuracy, proper installation and validity through referencing the equipment approval documents of the issuing certification agencies.

This step involves a physical examination of the equipment as well as site testing of the equipment to satisfy and required testing that is prescribed by the certification standards involved.

Upon resolution of any identified non-conformities, a detailed certification report is issued.  The report includes details of all pertinent information that was used in determining compliance with the certification standard(s) identified in the report.  Any special conditions of acceptability are also clearly identified in the report.

Upon issuance of a final certification report, the equipment is affixed with a Attesta’s HazLoc approval mark and the product make and model are added to the Attesta directory of certified products.  This information is available to any authority upon request.

Process Step 5:

This step is conducted by the owner of the equipment.  It involves the storage of the certification report in a location where it is accessible to responsible individuals.  It also involves training of all responsible persons that are in charge of health and safety of the establishment where the equipment is being utilized.  Since the report would likely contain some conditions of acceptability, it is important that these conditions are well understood by all persons that may impact the safety of the hazardous location equipment.