Contact Lithium Oil and Gas Oil & Gas Compliance , Hazardous Area Services – Lithium Oil & Gas (lithiumoilandgas.com) today to discuss inspection, testing and installation requirements of mechanical and non-electrical equipment within your hazardous areas.
Using explosion protected mechanical equipment in Australia which meets recognized industry standards for handling Flammable Liquids, Gases and Combustible Dusts is a good start, but is that enough to control the other, significant, ignition risk? Mechanical Ignition Mechanisms within Hazardous Areas?
Examples of recognized industry standards regarding the construction of these devices can include API Standards for Pumps and EN or AS/NZS standards for Industrial Trucks in Hazardous Areas, and so on.
In recent times, standards in the ISO/IEC 80079 series have been compiled, which may be used to provide guidance on possible ignition sources for mechanical equipment in hazardous areas. This Opinion Piece provides a brief introduction to ISO/IEC 80079-36 and ISO/IEC 80079-37.
What are Some Examples of Mechanical And Non-Electrical Equipment?
Examples of non-electrical equipment that may be used could include mechanical disc brakes, mechanical couplings, mechanical pumps, fluid couplings, oil filled gearboxes, oil filled disc brakes, hydraulic and pneumatic motors and any combination of them, which can either be used as a machine, or integrated into an overall machine. Examples are: fan, engine, compressor assemblies, etc.
When Does Mechanical Equipment Become a Problem?
Most people assume that Mechanical Equipment only becomes an issue if something fails, but this isn’t always the case. There are many mechanical devices that could become an Ignition Source, even when functioning as designed.
A bearing on a high-speed conveyor could fail and become a heat ignition source, capable of igniting Combustible Dusts. A Disc Brake, when it is operating normally, could also become hot enough to ignite some Combustible Dusts.
When determining the safety of Mechanical Equipment for use in a hazardous areas, the end user must consider if the equipment can become an effective ignition source during the mechanical equipment’s normal operation and entire expected lifetime.
Some of the possible sources of ignition from mechanical equipment include:
- Adiabatic compression (see Note)
- Exothermic Chemical reactions with process fluids or gases
- Hot surfaces
- Mechanical sparks (e.g., grinding and finishing, arc welding)
- Static electricity (e.g., fabric rubbing against plastics)
Note: The Adiabatic Compression of a gas causes a rise in temperature of the gas. Adiabatic expansion against pressure, or a spring, causes a drop in temperature. In contrast, free expansion is an isothermal process for an ideal gas.
Can You Buy Certified IECEx Mechanical Equipment?
Yes, when product sample testing, design assessment (a test report from an Ex-Testing Laboratory or ExTL) and quality assessment (Quality Assessment Report) are successfully completed, an Ex-Certificate of Conformity (IECEx or ANZEx) can be issued by an appropriate Accredited Certifying Body (or ACB).
Which ISO/IEC Standards Apply?
The International standards ISO/IEC 80079-36, and ISO/IEC 80079-37, specify basic methods and requirements for design, construction, testing and marking of non-electrical Ex-equipment and Ex-components.
- ISO/IEC 80079-36:2016 – Part 36: Non-electrical equipment for explosive atmospheres — Basic method and requirements
- ISO/IEC 80079-37:2016 – Part 37: Non-electrical equipment for explosive atmospheres — Non-electrical type of protection constructional safety ”c”, control of ignition sources ”b”, liquid immersion ”k”
Methods of Protection
For Non-electrical Equipment for use in Explosive Atmospheres Ex h (c, b or k) to be certified, the equipment is be subjected to a formal, documented ignition hazard assessment, in order to identify all potential ignition sources that can occur. The tests that are defined and performed are based on the findings of a risk assessment, which verifies that the applied control measures will effective, and that they will reduce the likelihood of any Potential Ignition Source, from becoming an Effective Ignition Source.
ISO/IEC 80079-37:2016 details the requirements for Non-Electrical Equipment, intended for use in Explosive Atmospheres. This standard covers three protection techniques:
Liquid Immersion “k” – this is a type of ignition protection where potential ignition sources are made ineffective or separated from the explosive atmosphere by either totally immersing them in a protective liquid, or by partially immersing and continuously coating their active surfaces with a protective liquid in such a way that an explosive atmosphere, which may be above the liquid, or outside the equipment enclosure, cannot be ignited.
Constructional Safety “c” – is a type of ignition protection where constructional measures are applied so as to protect against the possibility of ignition from hot surfaces, sparks and adiabatic compression generated by moving parts.
Control of Ignition Source “b” – is a type of ignition protection where mechanical or electrical devices are used in conjunction with non-electrical equipment to manually or automatically reduce the likelihood of a potential ignition source, from becoming an effective ignition source.
Note: The concepts for the types of protection “dh”, “ph” and “ht” can also be applied and are based respectively on the types of protection available for electrical equipment (IEC 60079-1, IEC 60079-2 and “t” defined in IEC 60079-31)
Marking of Certified Non-Electrical Equipment According to ISO/IEC 80079-36.
Similar to Ex-rated Electrical Equipment, the marking of the equipment must be legibly and indelibly marked on a main part of the equipment, on the exterior of the equipment. And should, where possible, be marked in a location which is visible after the equipment has been installed. The marking is required to show the following key information:
- Name of the manufacturer or its registered trademark and identification of manufacturing site;
- Manufacturer’s type identification;
- Year in which the equipment was manufactured;
- The symbol for each type of protection used:
- “h” – where only this ISO/IEC 80079-36 is applied
- “ch” – for constructional safety
- “bh” – for control of ignition source
- “kh” – for liquid immersion
- “ph” – for pressurisation
- “dh” – for flame-proof enclosure
Note: The concepts for the types of protection “dh”, “ph” and “ht” are based respectively on the types of protection available for electrical equipment (IEC 60079-1, IEC 60079-2 and “t” defined in IEC 60079-31)
There are also additional requirements which need to be marked depending on the specific intended use, design and testing of the equipment:
- For Equipment Group I, II or III, Including The Subdivision
- For Gases and Vapours (Group II Equipment) The Temperature Class or The Maximum Surface Temperature in °C,
- For Group III Equipment, The Maximum Surface Temperature in °C,
- The EPL,
- Permitted Ambient Temperature Ranges,
- A Serial Number,
- Certificate Reference,
- If Specific Conditions For Use Apply, The Symbol “X”,
- Warning Markings.
Installation and Maintenance.
The installation and use of the equipment in Australia must comply with any relevant Legislation, including state Acts & Regulations, and relevant standards that apply to that equipment and its installation location. Given the diversity of mechanical equipment, there are simply too many standards to list across the various industries and sectors.
However, critical supplementary information is listed in the Manufacturer’s Instructions. The manufacturer of the equipment must supply suitable documentation with the equipment, in accordance with ISO/IEC 80079-36. Instructions relevant to the safety and the safe use of the equipment are required. These instructions must be read, understood and applied by a competent person who is responsible for the installation, commissioning and ongoing maintenance of the equipment.
The instructions must cover important safety information such as:
- Installation details,
- Adjustment requirements,
- Putting into Service, and Commissioning,
- Safe and correct use,
- Assembling and dismantling,
- Maintenance requirements,
- Specific Conditions of Use.
Useful Reference Links
“This above information represents an opinion only and is of a general nature. The specifics of each individual situation must be taken into account with reference to the relevant Legislation, Codes of Practice and Australian standards. Professional advice should be sought if there is any doubt. These posts are not monitored, and the date of publishing must be taken into account as the information may be out of date.”