The unseen danger in hazardous zones

Within the petrochemical industry, safety and compliance are essential. One of the biggest risks that companies have to manage is that of fire or explosion. This is a sector that produces flammable substances which, when combined with heat or a spark, can cause untold damage and destruction and even loss of life.

A costly lesson – the Longford disaster

In 1998 that very situation occurred, at the Longford gas plant in Sale, when a leak of flammable gas came into contact with a spark, and the resulting explosion killed two workers, cut off Victoria’s gas supply for two weeks and caused an estimated loss to industry of 1.3 billion dollars.

The ongoing risk in petrochemical environments

Ignition sources are everywhere – even in something as seeming everyday as a phone or a light switch. It’s why petrol stations warn against using your mobile phone whilst filling up your car with petrol – there is a risk that a spark from the device could ignite the flammable fuel vapour.

Whist we safely turn on light switches in our homes every day, doing so in an environment with flammable materials could cause a fire or explosion.

This poses a challenge within the petrochemical sector when it comes to using electrical devices such as Programmable Logic Controllers. PLCs are widely used in the industry, as in many other sectors, to automate, control and monitor complex manufacturing and production processes in real-time. As electronic devices, they cannot be used in hazardous areas, where flammable gases, vapours or dust are present. Yet it is essential that they communicate with sensors that are located inside the hazardous area, and which generate vital process signals.

The role of IS interfaces in keeping sites safe

The solution is to separate the PLC from the hazardous area, through the use of Intrinsically Safe (IS) Interfaces. IS Interfaces – also known as IS galvanic isolators or IS barriers – are an isolation technology that separate the process signal sensors inside the hazardous area from the PLC located within a safe area. The signal is passed through the IS barrier so that it can be processed by the PLC, and the barrier does the vital job of blocking harmful electrical signals getting back into the hazardous area.

Understanding zone classifications

Hazardous areas are categorised into zones 0 to 2, with the following definitions:

• Zone 0 – Continuous or prolonged presence of an explosive gas atmosphere.
• Zone 1 – High possibility of an explosive gas atmosphere formation
• Zone 2 – Low possibility of an explosive gas atmosphere, and if it occurs, it will only persist for a short time.

To use a petrol station as an analogy: inside the storage tank or delivery tanker is zone 0, at the bowser whilst it is dispensing fuel is zone 1, and elsewhere on the forecourt is zone 2.

Areas other than zones 0-2 are called safe zones, or non-hazardous zones.

Petrochemical plants and sites use the same zone designation, albeit on a larger scale. PLCs are generally installed within safe zones. However, the PLC may need to communicate with process signal equipment that is located in zones 0, 1 or 2.

Process signal equipment located in zones 0 or 1 must use an Intrinsically Safe (IS) Interface to communicate with the PLC, isolating the latter from the high risk zones. Equipment in zone 2 must have the appropriate certification to ensure compliance.

Global certifications – what to look for

IS Interface devices must be certified for use within Zone 0 and/or Zone 1 hazardous areas. AS/NZS 60079 is the Australian Hazardous Areas standard. ATEX covers Europe, FM and UL the US, and IECEx provides international certification. Equipment certified under these schemes is safe to use in hazardous environments, protecting them from the risk of explosion and fire.

Expertise you can trust – PR Electronics and ECEFast

IS equipment is a specialised field and requires expert support. PR Electronics are an industry leader in the design and manufacture of IS Solutions for process automation. They offer IS interfaces, barriers, and isolators that comply with global standards and directives.

As the exclusive distributor for PR Electronics in Australia and New Zealand, ECEFast provides local businesses with a world-class solution combined with local expertise and support.

Safety and compliance without compromise

IS barriers enable petrochemical businesses to operate safely and with full compliance, without sacrificing the vital signal data that their PLCs need to receive. The PLC can still receive the signal, without having to be located within the hazardous area – reducing the risk explosion or fire, ensuring safety and security for assets and people.

To keep your plant and people safe, speak to ECEFast today about safe, compliant instrumentation solutions tailored to your site’s needs.