- Explosions can be prevented by reducing sufficient energy from escaping gases.
- Energy levels should be below the minimum ignition energy for any flammable gases and combustible dusts in the environment.
- If energy levels are kept below these thresholds, explosions will not occur.
- The most common way to limit energy is to design equipment to be inherently safe or to use intrinsically safe barriers, often used in transmitter installations.
- Intrinsically safe equipment is marked with the symbol (Ex i).
Intrinsic Safety (Ex i)
- Intrinsically safe (I.S.) equipment and wiring prevent explosions by limiting electrical energy enough to avoid igniting gases in the atmosphere, whether during normal operation or specific fault conditions.
- The energy reaching hazardous areas is restricted by an externally installed I.S. barrier.
- The advantages of intrinsically safe methods include:
- Less operator intervention is required to maintain a safe system.
- Easier equipment maintenance and repairs.
- Intrinsically safe devices have specified maximum limits for voltage, current, capacitance, inductance, and power supply.
- The allowed energy storage in the I.S. circuit depends on the magnitude of these parameters.
