This ensures that any sparks or hot surfaces produced by the equipment, even under fault conditions (e.g., short circuits, open circuits, component failures), cannot ignite the surrounding atmosphere.

Key characteristics of intrinsic safety:

• Energy Limitation: Voltage and current are strictly limited using components such as resistors, Zener diodes, and fuses.
• No Ignition Source: The design ensures that no spark or hot surface can release enough energy to ignite the hazardous atmosphere.
• Fault Tolerance: The system remains safe even with multiple independent faults (e.g., “ia” protection level withstands two faults).
• Use of Barriers: Intrinsically safe circuits are typically connected to non-IS circuits in a safe area through IS barriers that limit energy transfer.

Although intrinsically safe circuits are designed to remain non-igniting even under fault conditions—making them theoretically safe for live work in hazardous areas—live maintenance is generally NOT permitted or recommended on ships or in most industrial settings.

Reasons include:

• Regulatory Restrictions: Marine regulations, company safety systems, and permit-to-work procedures typically prohibit live work in hazardous areas regardless of equipment protection type. The standard requirement is to de-energize and obtain proper permits.
• Risk of Misidentification: Personnel may accidentally work on a non-IS circuit or introduce non-IS test equipment/tools into the hazardous zone.
• Unpredictable Faults: Incorrect installation, hidden damage, or unexpected circuit faults may compromise intrinsic safety.
• Best Practice: Always isolate, de-energize, and verify zero energy before maintenance in hazardous areas.

Thus, while IS circuits are designed to make live work safe, practical safety protocols and regulations almost universally prohibit live maintenance.

(c) Intrinsically safe equipment used onboard ship.

Intrinsically safe (IS) equipment is essential for safe operation in hazardous areas on ships—particularly tankers, gas carriers, and vessels transporting dangerous goods. Hazardous zones include cargo tanks, pump rooms, cofferdams, gas-dangerous deck zones, paint lockers, and battery rooms.

Common types of intrinsically safe equipment used onboard:

• Portable Gas Detectors: Used to check for flammable gases, toxic gases, or oxygen deficiency before entering enclosed or hazardous spaces. Designed so that batteries, sensors, and circuits cannot ignite vapours.
• Portable Two-Way Radios: Specially designed walkie-talkies preventing sparks or RF energy from igniting the atmosphere.
• Portable Lighting (Torches/Hand Lamps): Battery-operated lights engineered to prevent sparks at switches, filaments, or terminals.
• Tank Gauging Systems: Intrinsically safe sensors and transmitters installed in cargo tanks or pump rooms for measuring level, temperature, and pressure.
• Fixed Gas Detection Systems: Permanently installed sensors in hazardous spaces (e.g., pump rooms) that continuously monitor for gas leaks, with IS-certified local wiring.
• Process Control Instrumentation: Pressure transmitters, temperature sensors, valve indicators, and similar devices used in cargo handling systems within hazardous zones.
• Personal Electronic Devices: IS-certified phones, tablets, and cameras used during inspections or data collection.

All intrinsically safe equipment carries an ‘Ex’ marking, specifying the explosion protection type (e.g., Ex i, Ex ia, Ex ib) and the applicable gas group and temperature class.