Hazardous Areas - Combustible DUST explosive atmospheres
Hazardous Areas and Explosive Atmospheres, an explanation...
An area is considered a hazardous area when it contains three fundamental components: A flammable substance (which can be a gas, liquid, or solid), an oxidizer, 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 fibers.
An oxidizer is usually just the oxygen that is present in the open air.
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; anything which can cause spontaneous combustion of certain materials.
How do I know if my facility has a Dust Hazardous Area?
When all three of the elements described are present, including dust, fibres and/or flyings then you do. There is considerable discussion around some 'dusts' such as urea and Palm Kernal Extract. Please contact us if you have any doubts or need an assessment.
What are the applicable Standards?
The most current AS/NZS Standards are based on the international IEC-norms and are designated as the AS/NZS61241-series. Everything from General Requirements (Part 0), Area Classification (Part 10), Installation, Design and Selection (Part 14), Maintenance and Inspection (Part 17) and the requirements associated with various individual protection techniques. Parts of the AS/NZS60079-series also apply.
People carrying out work in these areas also must be able to demonstrate their level of competency as outlined in the AS/NZS 4761-series.
Does equipment in a hazardous area have to be regularly checked?
Yes and AS/NZS60079.17 describes the two main methods for doing this.
Most commonly is by Periodic Verification aka Periodic Assessment, where items are checked at least once every four years (Standards are currently being reveiwed with a look to reducing 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 type of assessment involves the engagment of a part-time competant person whose primary role is 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 finshed 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.