What is Intrinsically Safe?
Reprinted with permission from Fluke Corp.
Theres nothing routine about taking routine temperature measurements around flammable gases and chemicals! The presence of gases in certain environments can ignite explosions. Intrinsically safe devices can prevent explosions in hazardous locations by limiting the energy and surface temperature of the device under normal operation, or when conditions arise that could become hazardous. Plant engineers, managers and technicians working in petrochemical refineries and tank farms, oil exploration, offshore rigs, and petroleum and gas pumping stations need to take special precautions. Safety has always been a concern in hazardous working environments. New regulations have caused many involved professionals to look at the test tools used in these areas with renewed interest.
On July 1st, 2003 the European Unions ATEX directive requiring protective systems and products in potentially explosive work areas became mandatory. For the rest of the world, guidelines like the National Electrical Code NEC-500 and NEC-505, or other regulations patterned after this U.S. regulation, are in place, but are not always mandatory. Intrinsic safety is particularly important for technicians working in industries like petrochemical and pharmaceutical or any environment where explosive gases are present. The importance of safety in these environments cant be stressed enough. It takes a very small amount of energy to cause an ignition (e.g. ignition of a mixture of hydrogen in air requires only 20 uJ of energy). Proper practices and tools minimize the inherent risk involved in working around these hazards.
Intrinsic safety is a protection method employed in potentially explosive atmospheres. Devices that are certified as "intrinsically safe" are designed to be unable to release sufficient energy, by either thermal or electrical means, to cause ignition of flammable material (gas or dust/particulates).
Intrinsically safe standards apply to all equipment that can create one or more of a range of defined potential explosion sources:
- Electrical sparks
- Electrical arcs
- Flames
- Hot surfaces
- Static electricity
- Electromagnetic radiation
- Chemical reactions
- Mechanical impact
- Mechanical friction
- Compression ignition
- Acoustic energy
- Ionizing radiation
The three key elements of combustion are: - Inflammable Material (gases, particles/dust)
- Oxygen/Air
- Ignition Source
Typical industries and applications included: - Petrochemical
- Oil platforms and refineries
- Pharmaceutical
- Pipelines
- Gas supply utilities
- Gas-fired power generation
- Any environment where explosive gases are present
In these industries, classified areas include: - Areas in and around storage tanks of flammable materials.
- Gas compression pumps for moving gases through a pipeline or into a tank.
- Reaction vessels with the potential of a leak through a seal or access cover.
- Storage and handling areas for drums of susceptible materials.
- Processes with an explosive by-product (i.e. methane).
