A safer alternative for spark testing

Ground breaking research at CRCMining is set to revolutionise testing of devices for use in potentially explosive atmospheres such as underground coal mines, with the development of a safer, lower-cost electronic alternative to the Spark Testing Apparatus (STA).

In collaboration with ACARP and German Metrology Institute Physikalisch-Technische Bundesanstalt (PTB), researchers at CRCMining are developing an alternative to the electro-mechanical Spark Testing Apparatus (STA) that has been the standard for 50 years.

The research work was conducted in response to the many issues associated with the STA.

According to CRCMining, the STA apparatus only provides a pass/fail result, with a high degree of variability; tests are expensive, time consuming, and can only be carried out at a few specialised laboratories.

CRCMining’s new Electronic Spark Tester (EST) provides a more reliable, informative and versatile test method, and provides an intrinsically safety approach for better risk management in explosion protection.

Peter Henderson, engineering manager of underground operations at Glencore’s Coal Assets Australia division, has monitored the progress of the research work which has been funded by ACARP.

“This project has broken new ground in the understanding of intrinsically-safe (IS) equipment,” Henderson said.

“It has shown that the processes used to assess IS equipment are out-dated.  The ultimate outcome of this project will be a safer and more productive coal industry.”

He went on to state, “This is another great example of the coal industry working with professional and competent research organisations, such as CRCMining, to improve the knowledge and understanding of complex issues that are not just relevant to the coal industry, but the broader community as a whole.”

Enver Bajram, CRCMining’s project leader for the Electronic Spark Tester (EST), explained that unlike the STA, the EST does not require the creation of real sparks or explosions, instead a spark simulation is applied as a dynamic load to the device under test (DUT) using a custom designed electronic loading device.

“The EST then makes a series of measurements of the DUTs voltage and current response to the spark simulation and interprets these measurements based on knowledge of spark physics, developed from experiments undertaken specifically for this project,” Bajram said.

“The EST measures the response of the DUT and then provides an indication of spark energy and compares this to a known safe limit called an ignitability metric.

“The information provided by the EST gives engineers and the developer the ability to characterise the response of the DUT and determine its level of safety or level of failure rather than a pass or fail as is currently the case with the STA.”

“By removing the requirement for a specialised laboratory, the EST will enable a new approach where Intrinsic Safety (IS) testing can be conducted by developers, test houses, manufacturing facilities and on site personnel to ensure the ongoing safety of devices. Furthermore the EST will give the ability for every IS power supply to be tested as they roll off the production line, rather than a single device,” he said.

Rajiv Shekhar, CRCMining’s principal researcher for the EST project said results have shown that there are significant differences in the explosive limits between hydrogen and methane at low voltage levels that have not been previously studied.

“If this knowledge can be used to inform future changes to the standards then this could provide significant benefits to the affected industries by providing for higher powered, low voltage supplies without compromising safety,” Shekar said.

CRCMining has recently published a report detailing the project results and submitted a draft proposal to the International Electrotechnical Commission (IEC) for implementation into the IECEx 60079 standard. 

While continuing with this research, the team at CRCMining are providing a new design review and prototype testing service to assist manufacturers with meeting the requirements of the current standards.

In September 2015 CRCMining’s Electronic Spark Test research team received an ACARP Research and Industry Excellence Award for this project. 

ACARP executive director Mark Bennetts said the progress towards creating an Electronic Spark Tester as an alternative technique to the flawed existing spark test methodology is a remarkable achievement and will help the industry move forward with more certainty in this space.

“The fact that CRCMining’s research has been delivered in collaboration with German Metrology Institute PBT, indicates the potential for international change of both testing and eventually International Electrotechnical Commission (IEC) standards,” Bennetts said.


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