IS Barrier on Tanker Ship

In order for an explosion to occur, three components are needed: gas/dust, oxygen, and a source of ignition such as heat or a spark. The concept of Intrinsic Safety involves removing the source of ignition by utilizing devices like Zener Barriers or Galvanic Isolators.


An IS (intrinsically safe) barrier is a type of electrical safety device that is used to protect equipment and personnel in potentially explosive environments by limiting the voltage and current, thus reducing the amount of energy that enters the hazardous area. IS barriers are often used in areas where flammable gases or liquids are present, such as cargo holds or fuel tanks.


The voltage is controlled by a Zener diode, while the current is regulated by an output resistor, with a fuse in place to protect the Zener diode. The Intrinsically safe earth is crucial to providing protection, as all the components involved are considered “Safety Components”. Zener barriers are typically designed for zone 0 connectivity (Exia), but can also be used for zones 1 and 2 (Exib and Exic). In order to ensure that the safety components cannot fail, they are assessed for duplication (Zener diodes) and two faults for Exia.


Design for Intrinsic Safe barrier


Tanker vessels are categorized as CLASS-I due to the nature of the 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 with IS equipment contain an internal explosion without causing an external hazard.

For Advanced Read, check out:Marine Electrical Safety

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