Hazardous Areas and Flammable GAS Explosive Atmospheres
Hazardous Areas and Explosive Atmospheres, an explanation...
An area is considered to be hazardous when it contains three fundamental components: A flammable substance, an oxidizer (such as air), and a source of ignition.
A flammable substance can be anything from gases and liquids such as hydrogen, gasoline and kerosene, to solid particulates such as dust or small fibres.
The most common oxidizer is the oxygen present in the open air.
In this instance, a source of ignition can be something obvious like a spark or open flame, or something seemingly less obvious like excessive heat generated by friction; it can be anything which causes spontaneous combustion.
What are the applicable Standards?
The most current AS/NZS Standards are based on the international IEC-norms and are designated as the AS/NZS 60079-series. Everything from General Requirements (Part 0), Area Classification (Part 10), Installation, Design and Selection (Part 14), Maintenance and Inspection (Part 17) and all of the requirements associated with all the known individual protection techniques.
Also, people carrying out work in these areas must be able to demonstrate their level of competency as outlined in the AS/NZS 4761-series.
Where do my Zones start and end?
We get asked this a lot so here's a copy of part of a letter I sent to a prospective client, it may be helpful to you too. The background is that this is for an above ground petrol tank fitted with a single-phase motor/pump unit. . .
Dear Sir,
. . . Without seeing the equipment and being able to make an onsite assessment it is not possible for me to definitively state the physical size or dimensions of your Zones however experience indicates you can expect the inside of the tank/vessel i.e. the top dead space will be Zone 0. A spherical area outside the tank including the filling point and the pumping equipment, also any delivery hose joints or connections and the hose outlet nozzle will be Zone 1.
A further spherical area beyond the Zone 1 might exist and would therefore be Zone 2 but again, an assessment would be needed to confirm these.
I know you’re keen to identify the actual distances each Zone extends to and from which point, so, you might like to refer to AS/NZS 60079.14 for more information.
What are Inspectors looking for?
As inspectors, we inspect and certify to AS/NZS 60079.17. We look for a hazardous area dossier (described in AS/NZS 60079.14) as it will contain all the certification documents with drawings and equipment information. We look at the physical installation including its signage and labelling. We will want an explanation on how emergency events are identified and handled. We'll also apply the standard electrical testing requirements found in section 8 of AS/NZS 3000.
The inspection and certification process will result in an electrical Record of Inspection and to us submitting a record to the WorkSafe NZ / Energy Safety’s High-Hazards database.
Does equipment in a hazardous area have to be regularly checked?
Yes and AS/NZS60079.17 describes the two main methods of doing this. Firstly and most common is by Periodic Verification aka Periodic Assessment, where items are checked at least once every four years (Standards are currently being reveiwed and the Draft is looking to reduce this frequency to 3 years). Some items may need to be checked more regularly either because of manufacturer requirements or because of technical or operational use. Typically this involves the engagment of a competant person to inspect, audit and report.
Secondly there are "Continuous Supervision" provisions which may apply where equipment that is regulalrly used, visited or maintained by personnel who are deemed to be competant; may "pass" the item as being suitable for purpose once they've finished working on the equipment. These provisons apply where oversight is provided by a Technical Person with Executive Function (TPEF).
The pros and cons of each method are varied and we can provide you with a presentation to help you choose which method best meets your needs.
What is a Verification Dossier?
An extract from AS/NZS60079.14 states; "A Verification Dossier is a set of documents showing the compliance of electrical equipment and installations." Often referred to as a VVD, Section 4.2 in this Standard sets out the requirements.
A VVD can be as simple as a folder containing the manufacturer’s operating and maintenance instructions, drawings, location test certificate (if required), electrical compliance certificates (past and present), maintenance records, and a statement made by the owner confirming the address and other contact details.
VVD's can also be computer based however a physical electrical compliance certificate in the form of a Certificate of Verification and/or a Record of Inspection is still required to be issued by an examining authority (like us) which then describes where the VVD and their associated files are being held.
VVD's are required to be available for audit.
We can help you to prepare and maintain your VVD and we can provide assistance during your preparation for an external audit.
What is a High-Risk Database Record?
WorkSafe NZ and Energy Safety (ES) are both divisions within The Ministry of Business, Innovaton and Employment. WorkSafe NZ now operates and administers a web-based Records Register whose focus is on identifying all high-risk locations in New Zealand.
Electrical inspectors are required to 'register' their activities as an entry (Record) on to the Register whenever they complete an inspection of all types of high-risk work. The two most common examples are when the mains gets inspected for the first time at a new installation and anytime a high-risk activity occurs within a hazardous area location. There are several other examples; too many to explain in this FAQ so please check out this link for a comprehensive list and other information.
What is a Location Compliance Certificate?
An annually renewable Location Compliance Certificate is required where explosive, flammable or oxidizing substances are stored and the quantity exceeds the thresholds specified in the legislation. Follow this link for more details on Location Compliance Certification.
How can I find a Compliance Certifier?
WorkSafe NZ maintain a Register of Compliance Certifiers. Here's the link.
What is an Owner’s Statement?
It is much like a memo, often prepared on the owner’s letterhead stating who the owner is and if the operator is a different entity, the Statement records who they are. It also records the location of the premises, the intended use of the equipment and where the Dossier is being held. The Owner's Statement stays in the Dossier.
What drawings are needed?
Inspectors need to satisfy themselves that equipment is suitable for purpose and electrically safe for the areas they operate in. Whilst manufacturer manuals and Certificates of Conformity provide evidence of equipment suitability, there is also a need to confirm the type of location that equipment is going to be used in. This is easiest done in drawings such as Hazardous Area Classification drawings, electrical schematics, location and equipment layout drawings, P&ID's, and instrument loop drawings. Where drawings are not available, we can create them for you.
What types and grades of inspection are needed?
There are 4 Types of Hazardous Area Inspections: (Reference AS/NZS 60079.17:2009 4.3.3)
1. Initial Hazardous Area Inspections
Initial inspections are required to ensure that the selected type of protection is appropriate for the hazardous area installation and applies to new installations.
2. Periodic Hazardous Area Inspections
Periodic inspections should be carried out as part of an inspection regime or maintenance routine and applies to existing installations. The purpose of the periodic inspection is to monitor the effects of deterioration or change. The intervals between periodic inspections should not exceed three years.
3. Sample
This type of inspection offers an engineered solution where a representative sample of devices, installed in similar circumstances and used in a similar service can be inspected to any of the Grades of Inspection. This is a common method of inspection on production lines.
4. Repair/Replacement
This type of Inspection is required the work has been completed and prior to placing it back into service. There are allowances for temporary livening for testing.
There are 3 Grades of Hazardous Area Inspections:(Reference AS/NZS 60079.17:2009 4.3.2)
1. Visual Hazardous Area Inspections
Visual hazardous area inspections identify without the use of access equipment or tools which will be apparent to the eye. For example - missing bolts, deformed/damaged enclosures, missing tags, debris encrusted encloures
2. Close Hazardous Area Inspections
Close hazardous area inspections encompasses those aspects covered by a visual inspection, and in addition, identifies those defects, such as loose bolts, which will be apparent only by the use of access equipment, for example, steps (where necessary) and tools. Close inspections do not normally require the enclosure to be opened, or the equipment to be de-energized.
3. Detailed Hazardous Area Inspections
In addition to the aspects covered by a Close inspection other items defects such as whether there are suitable and/or loose terminations. These items can only be identified by opening the enclosure and using where necessary, tools and test equipment. These inspections may require the enclosure to be opened, equipment to be de-energized and dismantling of cable glands where applicable, as per the AS/NZS60079-17/14 Electrical Installations Inspection & Maintenance Standards.
Do you have any other questions? Give us a call. . .