Intrinsic safety (IS) is a method of providing safe operation of electronic process-control instrumentation in hazardous areas. IS systems keep the available electrical energy in the system low enough that ignition of the hazardous atmosphere cannot occur.
No single field device or wiring is intrinsically safe by itself (except for battery-operated, self-contained devices), but is intrinsically safe only when employed in a properly designed IS system. The concept of intrinsic safety recognizes that an energy discharge limit exists below which ignition cannot be brought about. The concept also recognizes the possibility of failure within the electrical equipment and requires that safety not be impaired by the occurrence of faults within the equipment or protective mechanism.
As shown above, most applications require a signal to be sent out of or into the hazardous area.
The equipment mounted in the hazardous area must first be approved for use in an intrinsically safe system. The barriers designed to protect the system must be mounted outside of the hazardous area (as shown above) in an area designated as non-hazardous or safe in which the hazard is not and will not be present.
Intrinsic Safety Barriers
- Definition: An intrinsic safety (IS) barrier is a safety device that helps control the energy flow into a hazardous location.
- Application: IS barriers are typically used alongside traditional two-wire 4-20 mA instruments to ensure safety in hazardous areas.
- Analog Instrumentation: For traditional analog instrumentation, energy can be limited in the field, with or without a ground connection, by using an appropriate safety barrier.
