When is intrinsically safe mobile phone necessary?

When equipment is used in areas where combustibles are present, measures must be taken to minimize the risk of ignition. the OHSA accepts IS design as an appropriate approach, although it requires that the entire system be designed accordingly. Simply using is-certified components is not enough.

The exception to the need for certification is in the case of “simple instruments”. This is a term used for very low power or passive devices that do not cause ignition. Thermocouples and RTDs are good examples.

How do intrinsically safe mobile devices work?

Avoiding ignition requires a reduction in available power and maximum temperature. Defining the maximum available power is complex, but in general it can be taken to mean less than 29 V and less than 300 mA. A simpler view is that the power must be less than 1.3 w (note that many instruments require 24V and can often be designed for less than 500 mA; enough to meet IS certification in many cases).

Six categories define the temperature rating. In general, devices that meet the T4 designation are considered intrinsically safe because the temperature will not exceed 135°C (275°F) (devices that dissipate less than 1.3 W are typically kept below this temperature).

What types of intrinsically safe equipment are there?

A wide variety of industrial equipment, such as intrinsically safe mobile phone, flashlights, cameras, gas detectors and even radios, are available in intrinsically safe forms. In terms of instrumentation, the greatest need is for pressure and weight measurements. Temperature measurements usually meet the “simple instrumentation” rule, although temperature transmitters may need to send thermocouple signals over longer distances.

Is intrinsically safe certified equipment more expensive than non-certified equipment?

Typically, IS devices are slightly more expensive than non-certified versions. This comes more from obtaining and maintaining approval than from the cost of additional or uncommon components. the basic design of the IS barrier uses zener diodes to limit voltage, resistors to limit current and fuses, none of which are expensive.

What are the benefits?

IS provides several benefits when electrical equipment and instrumentation must be placed in a hazardous environment.

It helps ensure a safe working environment and protects those nearby from the risk of explosion.
It avoids the cost and bulk of an explosion-proof enclosure. The use of standard instrumentation cables saves additional costs.
Maintenance and diagnostic work can be performed without shutting down production and work area ventilation.
Insurance premiums may be reduced due to the reduced risk.

Does intrinsically safe equipment replace explosion-proof or pressurized?

Intrinsically safe equipment cannot replace these methods in all applications due to the reliance on low power and low temperature. Where possible, it usually results in significant installation and maintenance cost savings.

Does intrinsically safe affect the performance of certified devices?

No. Performance is the same as non-certified products with higher reliability. These devices use the same components as non-certified devices, but have been designed to limit the amount of energy stored and heat generated in the event of an internal failure.

Protecting People and Property

Many industrial, chemical and process environments present a significant risk of explosion due to the presence of flammable gases and vapors, dusts or fibers. Such environments are referred to as “hazardous” environments and must be designed to eliminate the possibility of ignition of flammable materials.

In such environments, it is often necessary to use instruments that are electrical in nature. When this is unavoidable, there are three possible approaches: place the equipment in an explosion-proof enclosure, purge the enclosure with an inert gas, or use intrinsically safe design principles.

IS design minimizes the generation of power and heat. The equipment must be independently IS certified and the entire system must be designed to IS standards before it can be put into service. However, using an IS design simplifies installation, saves money, maintains energized equipment and, most importantly, makes the workplace safer.