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.
