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What is SANS 10108 and why is it important for hazardous locations?
SANS 10108 is a South African national standard that provides guidelines for the classification of hazardous locations and the selection of equipment for use in such locations. Hazardous locations are areas where there may be significant risk of the ignition of gas, dust or vapour, which could result in fire or explosion. SANS 10108 aims to prevent such incidents by specifying the appropriate zoning, protection methods and installation requirements for electrical and non-electrical equipment in hazardous locations.
SANS 10108 is based on the international standards IEC 60079 and IEC 61241, which cover explosive atmospheres due to gas and dust respectively. SANS 10108 also incorporates some specific requirements for the South African context, such as mining and civil blasting applications, lightning protection and escape breathing apparatus. SANS 10108 is applicable to all industries that deal with flammable substances, such as oil and gas, petrochemicals, pharmaceuticals, food processing, wood processing and waste management.
SANS 10108 defines three zones for hazardous locations based on the frequency and duration of the occurrence of an explosive atmosphere: Zone 0 (continuous), Zone 1 (occasional) and Zone 2 (rare). Each zone has different requirements for the type and level of protection that equipment must have to prevent ignition sources. Some of the common protection methods are flameproof (Ex d), increased safety (Ex e), intrinsic safety (Ex i), encapsulation (Ex m), pressurization (Ex p) and non-sparking (Ex n).
SANS 10108 also specifies the installation requirements for equipment in hazardous locations, such as wiring, earthing, bonding, sealing, marking and inspection. SANS 10108 references other standards that provide more detailed information on these aspects, such as SANS 10142-1 for low-voltage installations and SANS 60079-14 for electrical installations in explosive gas atmospheres.
SANS 10108 is an essential standard for ensuring safety in hazardous locations. It helps to identify and classify the potential sources of ignition, select the appropriate equipment for each zone and install it correctly to prevent accidents. SANS 10108 also facilitates compliance with the legal obligations under the Occupational Health and Safety Act (OHSA) and the Mine Health and Safety Act (MHSA) in South Africa.
To access the full text of SANS 10108, you can purchase it from the South African Bureau of Standards (SABS) website[^1^] or download it from other online sources[^2^] [^3^].
In this article, we will discuss some of the key concepts and terms related to SANS 10108 and hazardous locations. We will also provide some examples of how to apply SANS 10108 in practice.
Explosive atmosphere
An explosive atmosphere is a mixture with air, under atmospheric conditions, of flammable substances in the form of gas, vapour, dust, fibres or 'flyings' which, after ignition, permits self-sustaining propagation. An explosive atmosphere can be ignited by various sources of energy, such as sparks, flames, hot surfaces, static electricity, electromagnetic radiation or mechanical impact.
An explosive atmosphere can only exist within a certain range of concentration of the flammable substance and the oxidizing agent (usually oxygen). This range is defined by the lower explosive limit (LEL) and the upper explosive limit (UEL) of the substance. Below the LEL, the mixture is too lean to ignite; above the UEL, the mixture is too rich to ignite. The LEL and UEL vary depending on the type and temperature of the substance and the pressure and humidity of the air.
The presence and extent of an explosive atmosphere depend on several factors, such as the properties and quantity of the flammable substance, the ventilation and dispersion conditions, the temperature and pressure variations and the possible sources of release or leakage. SANS 10108 provides methods for assessing these factors and determining the likelihood and duration of an explosive atmosphere in a given location.
Zoning
Zoning is a process of dividing a hazardous location into zones according to the frequency and duration of the occurrence of an explosive atmosphere. Zoning is essential for selecting the appropriate equipment for each zone and ensuring its compatibility with the level of risk. Zoning also helps to define the boundaries and extent of hazardous locations and to communicate them clearly to all personnel involved.
SANS 10108 defines three zones for hazardous locations due to gas or vapour: Zone 0, Zone 1 and Zone 2. Zone 0 is an area in which an explosive gas atmosphere is present continuously or for long periods or frequently. Zone 1 is an area in which an explosive gas atmosphere is likely to occur in normal operation occasionally. Zone 2 is an area in which an explosive gas atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only.
SANS 10108 also defines three zones for hazardous locations due to dust: Zone 20, Zone 21 and Zone 22. Zone 20 is an area in which an explosive dust atmosphere in the form of a cloud of dust in air is present continuously or for long periods or frequently. Zone 21 is an area in which an explosive dust atmosphere in the form of a cloud of dust in air is likely to occur in normal operation occasionally. Zone 22 is an area in which an explosive dust atmosphere in the form of a cloud of dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.
The zoning process involves identifying all possible sources of release or leakage of flammable substances, estimating their rate and quantity of release, evaluating the ventilation and dispersion conditions, calculating the extent and duration of the explosive atmospheres and assigning zones accordingly. SANS 10108 provides tables and diagrams that illustrate typical examples of zoning for various types of equipment and processes.
Protection methods
Protection methods are techniques or measures that prevent ignition sources from causing explosions in hazardous locations. Protection methods can be applied to electrical or non-electrical equipment or to both. Protection methods can be classified into two main categories: explosion prevention and explosion protection.
Explosion prevention methods aim to prevent the formation or presence of an explosive atmosphere by controlling or eliminating one or more elements of the fire triangle (oxidizing agent, fuel or energy source). Examples of explosion prevention methods are ventilation, inerting, purging, dilution, segregation and isolation.
Explosion protection methods aim to prevent ignition sources from igniting an explosive atmosphere by limiting or containing their effects. Examples of explosion protection methods are flameproof (Ex d), increased safety (Ex e), intrinsic safety (Ex i), encapsulation (Ex m), pressurization (Ex p) and non-sparking (Ex n).
SANS 10108 provides guidance on how to select the appropriate protection method for each zone and type of equipment. SANS 10108 also references other standards that provide more detailed information on each protection method, such as S
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