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The safest way to calibrate

There are industrial environments where calibrations should not only be made accurately and efficiently, but also safely. When safety becomes a priority in calibration, intrinsically safe calibrators enter the picture.

Intrinsic safety (IS) is a protection technique for safely operating electronic equipment in explosive environments. The concept has been developed for safely operating process control instrumentation in hazardous areas. The idea behind intrinsic safety is to make sure that the available electrical and thermal energy in a system is always low enough that ignition of the hazardous atmosphere cannot occur.

A hazardous atmosphere is an area that contains elements that may cause an explosion: source of ignition, a flammable substance and oxygen.

Hazardous area classifications in IEC/European countries are:

Zone 0: an explosive gas & air mixture is continuously present or present for a long time.

Zone 1: an explosive gas & air mixture is likely to occur in normal operation.

Zone 2: an explosive gas & air mixture is not likely to occur in normal operation, and if it occurs it will exist only for a short time.

An intrinsically safe calibrator is therefore designed to be incapable of causing ignition in the surrounding environment with flammable materials, such as gases, mists, vapours or combustible dust. Intrinsically safe calibrators are also often referred to being ‘Ex calibrators’, ‘calibrators for Ex Areas’, or ‘IS calibrators’. An Ex Area also refers to an explosive environment and an Ex calibrator is a device designed for use in the type of environment in question.

Where is it required?

Many industries require intrinsically safe calibration equipment. Intrinsically safe calibrators are designed for potentially explosive environments, such as oil refineries, rigs and processing plants, gas pipelines and distribution centres, petrochemical and chemical plants, as well as pharmaceutical plants. Basically, any potentially explosive industrial environment can benefit from using intrinsically safe calibrators.

What are the benefits?

There are clear benefits in using intrinsically safe calibration equipment. First of all, it is the safest possible technique. Secondly, the calibrators provide performance and functionality.

Safest possible technique: Intrinsically safe calibrators are safe for employees, as they can be safely used in environments where the risk of an explosion exists. In addition, intrinsically safe calibrators are the only technique permitted for Zone 0 environments (explosive gas and air mixture is continuously present or present for a long time).

Performance and functionality: Multifunctional intrinsically safe calibrators provide the functionality and performance of regular industrial calibration devices, but in a safe way. They can be used for calibration of pressure, temperature and electrical signals. A documenting intrinsically safe calibrator provides additional efficiency improvements with its seamless communication with calibration software. This eliminates the need of manual recording of calibration data and improves the quality and productivity of the entire calibration process.

What’s the difference?

Intrinsically safe calibrators are different from other industrial calibrators in both design and technical features. In view of safety, there are also some guidelines and constraints for how to use them in hazardous areas. Every intrinsically safe calibrator is delivered with a product safety note, which should be read carefully before using the device. The product safety note lists all the ‘dos and don’ts’ for safe calibration.

The differences in design and technical features were made with one purpose in mind—to ensure that the device is safe to use and is unable to cause an ignition. The surface of the device is made of conductive material.

The battery of an intrinsically safe calibrator is usually slower to charge and it discharges quicker. Some intrinsically safe equipment operates only with dry batteries, and some with chargeable batteries. When charging the battery, it must be done in a non-Ex area.

External pressure modules can be used with IS-calibrators, but they must also be intrinsically safe. There are also usually small differences with electrical ranges compared to regular industrial calibrators (e.g. maximum is lower).

What are ATEX and IECEx?

ATEX (‘ATmosphères EXplosibles’, explosive atmospheres in French) is a standard set in the European Union for explosion protection in the industry. ATEX 95 equipment directive 94/9/EC concerns equipment intended for use in potentially explosive areas.

Companies in the EU where the risk of explosion is evident must also use the ATEX guidelines for protecting the employees. In addition, the ATEX rules are obligatory for electronic and electrical equipment that will be used in potentially explosive atmospheres sold in the EU as of 1st July, 2003.

IEC (International Electrotechnical Commission) is a non-profit international standards organisation that prepares and publishes International Standards for electrical technologies. The IEC TC/31 technical committee deals with the standards related to equipment for explosive atmospheres. IECEx is an international scheme for certifying procedures for equipment designed for use in explosive atmospheres.

The objective of the IECEx Scheme is to facilitate international trade in equipment and services for use in explosive atmospheres, while maintaining the required level of safety. Calibrators certified according to ATEX and the IECEx Scheme are fit for their intended purpose and sufficient information is supplied with them to ensure that they can be used safely.

Is service different?

There are certain aspects that need special attention when doing service or repair on an intrinsically safe calibrator. The most important thing to remember is that an intrinsically safe calibrator must maintain its intrinsic safety after the service or repair. The best way to do this is to send it to the manufacturer or to an authorised service company for repair.

Recalibration can be done by calibration laboratories (still preferably with ISO/IEC 17025 accreditation).

*Villy Lindfelt

Beamex Oy Ab

Distributed in Australia by AMS Instrumentation & Calibration Pty Ltd

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