Why to choose intrinsic safety?

Intrinsic safety (IS) is a low-energy signaling strategy that avoids explosions by ensuring that the energy transmitted to a dangerous area is well below the energy needed to cause an explosion.

The energy levels made available for signage are low but useful and more than sufficient for most instrumentation systems.

Advantages of intrinsic safety:

The main advantage of intrinsic security is that it provides a solution to all hazardous area problems (for equipment that needs limited power) and is the only methodology that fulfills this criterion. The key factors are as follows:

  • The intrinsic standard is accepted in local and international level.

  • Usually the same IS equipment meets both dust and gas hazards requirements.

  • Intrinsically safe devices can be used in all hazardous zone. In general, it is the only option for Zone 0 instrumentation that has a satisfactory security record.

  • A IIC group gas classification is usually assigned to intrinsically safe apparatus and systems which ensures that the equipment is compatible with all fuel / air mixtures.

  • Usually, a T4 (135 ° C) temperature level is reached that satisfies the requirement for all industrial gasses except for carbon disulfide (CS2), which is luckily rarely used.

  • The device and the system in which it is used can be made at an acceptable cost by ’ ia IIC T4. ’ In almost all circumstances, this eliminates concerns about area classification, gas grouping, and temperature classification and becomes the universal safe solution.

  • The idea of ’ simple devices ’ allows most simple devices such as switches, thermocouples, RTDs and junction boxes to be used in inherently secure systems without the need for certification.

  • The intrinsic security technique is the only technique that allows for live maintenance in the dangerous area without having to seek certificates of ’ gas clearance. ’ This is especially important for instrumentation, as it is difficult to find faults in de-energized equipment.

  • The specifications for installation and maintenance of inherently secure equipment are well established and consistent regardless of the level of security. It reduces the amount of training required and reduces the likelihood of harmful errors.

  • Intrinsic protection allows modern instrumentation cables to be used, thus reducing costs. Cable strength and inductance are often viewed as a concern, but in reality it is only a problem on cables longer than 400 metres, in systems installed in zones 0 and 1, where IIC gasses (hydrogen) are the source of threat.


Intrinsic safety is basically a low-energy technique and the voltage, current and power available are therefore limited.

A simple approach is to suggest that if the system can be controlled from a power source whose output parameters are within the (blue) hatched region then it can be made intrinsically secure according to’ IIC ia T4’ requirements. If the criteria surpass these limits to a limited degree then the specifications for IIB or’ ic’ are likely to be made intrinsically free.

Nonetheless, the first choice is always to choose the IIC ia T4 ’ equipment if it provides adequate energy and is an economical choice, as this equipment can be used in all situations (except if carbon disulfide [ CS2 ] is the hazardous fuel, in which case other problems arise).

For all issues with low voltage instrumentation, intrinsic protection is the natural choice. There are appropriate approaches that are consistent with all classifications of gases and areas. The method avoids fires instead of maintaining them, which should be better, and the facility for’ live repair’ enables the use of traditional instrument training.