How ship electrical equipments are protected and categorized to operate in an area with high concentrations of flammable gases, vapors or liquids?
Ship EX Areas protection, Intrinsic safety IS
A protection technique called INTRINSIC SAFETY (IS) are used for electrical equipment in HAZARDOUS AREAS by limiting the ELECTRICAL and THERMAL ENERGY. It is usually applied to an equipment and wiring which is incapable of releasing sufficient electrical or thermal energy under normal or abnormal conditions to cause ignition on a hazardous environment.
Ship Explosion Hazardous areas
IS is a low energy technique where the CURRENT, VOLTAGE and POWER is reduced to a level too low to cause ignition. In general, less than 1.3 WATTS is the maximum power level were available.
Equipment that are rated “Ex” has been classified as safe for use in hazardous areas, often referred to as “Ex Areas”. Explosion Hazardous Areas (Ex Zone) are divided into different Zones according to risk probabilities. 0 Zones have the highest risk probability while 2-Zones is the lowest probability.
Electrical protection of ship Explosion Hazardous areas
Hazardous locations are categorized by Class, Group, and Division as follows:
ship Explosion Hazardous areas (CLASS-I)
Denotes AREAS where FLAMMABLE GAS, VAPOR, or LIQUID is present.
ship Explosion Hazardous areas (CLASS-II)
Denotes AREAS where COMBUSTIBLE DUST is present.
ship Explosion Hazardous areas (CLASS-III)
Denotes AREAS where IGNITABLE FIBERS are present.
EX equipment on ship system
All of these locations where classified by International Electromechanical Commission (IEC) by publishing series of standards, they are also categorizing and testing all equipments designed in hazardous locations known as “Ex equipment”.
IS Barrier on tanker ship
Tanker vessels are categorized as CLASS-I due to the nature of cargo and explosive environment. Intrinsically Safe Barriers (IS Barriers) are commonly used in Tank Gauging and Level Monitoring, pressure sensors and thermocouples are needed to be contained in releasing any electrical and thermal energy.
Enclosures that are NEMA classified are designed to contain an internal explosion without causing an external hazard.
Explosion proof motors designed in hazardous locations are also classified according to class, group and division they are intended to operate. Portable devices like cameras, cellphones, flashlights, lamps and even tools are strictly monitored having an approved “Ex” classification in order not to create any energy that will resulted to a catastrophic explosion.