Sensor Technology to Enhance Gas Detection Safety in Asia Pacific

Wilson Tan
Business Leader for City Technology in Asia Pacific
Wilson Tan, Business Leader for City Technology in Asia Pacific, is a gas sensing expert well-versed in the importance of high quality sensing principles and why they are so essential to high performance gas detec tion. Wilson Tan talks to Of fshore World about the challenges facing many industries, like offshore oil and gas, where the considerable dangers make highly sensitive sensor detection even more important than ever.

Twenty years ago, we all bought computers with little understanding of inner component workings or the clever technology that actually made our device perform so well and effectively. Today, thanks to a highly effective global marketing campaign from a leading processing chip manufacturer, who taught us to 'look inside' our PCs, we now all appreciate that our computers are only ever as good as their processing capacity, regardless of any other impressive functionality they might offer.

This is a good analogy for the gas detection industry; there is much focus on the gas detection solution itself and all the value such a device can bring in terms of enhancing safety, reducing costs or providing simplified use, but the sensor component itself is equally important.

A gas detector is comprised of essentially two core elements; its sensor, which provides the means of identifying and quantifying a certain gas in the surrounding atmosphere and its hardware/software, which uses this data to deliver real-time concentration readings and trigger alarms, if pre -defined levels are reached. Both aspects are critical and without a high -quality sensing element, a gas detector is nothing more than electrical components and software that has no real use or value.

Failure is Not an Option
In reality, a sensor has a very hard job to undertake - not only must it detect gas risks, but it must do so consistently in all environmental conditions it may be subjected to. The sensor must also be selective only to the gas it is detecting because cross-interference can cause inaccurate readings. Added to these aspects is a need for a sensor to be able to protect itself from compounds that can adversely affect its detection; namely ingress by particulates or water and also potential 'poisoning' from reactive compounds in the atmosphere that could adversely affect its performance.

In today's ever-more safety conscious World, the protection of assets and personnel is always top of mind for businesses but industries like off-shore oil and gas demand the highest levels of performance and enhanced safety, owing to the sizeable explosive and toxic risks presented by the myriad of gases present. These include diverse Hydrocarbons like Methane (CH4) and toxic gases like Hydrogen Sulphide (H2S), Carbon Monoxide (CO), Carbon Dioxide (CO2) and Sulphur Dioxide (SO2) and also Oxygen (O2) depletion.

The applications for gas detection in the upstream industry are diverse. Driller stands, mud return line receiver tanks and pit rooms, compressors, pipelines and seals all require flammable, H2S and O2 monitoring. Water supplies need flammable and H2S, CO2, SO2 and NOx toxic gas detection to monitor run off gullies.

HVAC ventilation systems and air intakes require flammable and toxic cross -duct remote sensor mounting for effective monitoring. If H2S is being removed from crude mix on a platform, dehydration and temporary refuge area /H2S refuges should also be monitored for flammables and toxics including CO2, SO2 and H2S.

Platform processes are designed to deliver maximised yield and gas detection must be capable of delivering not only high sensitivity but maximised uptime and stability; just one nuisance alarm that requires a process shutdown of 60 minutes on an oil rig producing 15,000 BPD, can equate to a revenue loss of USD 60,625 (based on a 24 hour production day and a price of USD 97/barrel - barrel price source: Financial Times).

Geological and Environmental Impacts
Aside from the obvious associated industry risks, it is worth noting that regional factors in Asia Pacific can have a considerable impact and increase the dangers, making sensitive, accurate, high performance detection even more imperative to worker safety. Although fracking is an on-shore activity, it does provide a good example of environmental impact. Shale gas reserves in the Asia Pacific region typically exist in deeper wells that can also feature increased geological complexity and this can cause higher levels of H2S to be present. The abundance of CH4 also makes flammable sensor performance key to application safety. Added to this are other local factors such as the location of shale gas reserves, which are predominantly in the arid west and southwest, where temperatures are high and humidity is low.

What to Look for in a Sensor
I am often asked what to consider when selecting the right sensor solution. The oil and gas industry provides the ideal context to highlight the core attributes needed, because it represents some of the most challenging locations for gas sensors to work in. There is the potential for ingress by compounds and water vapour/sea spray that must be prevented using filters, sinters and small capillaries. Ambient conditions can change dramatically and temperature can fluctuate considerably in a single day in arid locations . Sensors from leading manufacturers should be designed and tested to respond to such conditions, working between -40°C and 55°C making them capable of meeting the needs of Asia Pacific. They should include technologies and components that allow the sensor to adapt quickly to large temperature fluctuations effectively so diurnal fluctuation in arid locations is not an issue.

Other Sensor Challenges
Humidity is a particular concern for Electrochemical Cell (ECC) sensors, which use an aqueous system that is potentially susceptible to humidity effects. Leading-edge ECC sensors should be able to work effectively between across a wide range of RH conditions, meeting the demands of even the most challenging locations through their intelligent component design, which must prevent drying out or saturation.

Accidents happen and devices can easily be dropped, so sensors need to be highly robust and capable of withstanding impacts and mechanical vibrations. Drop tests should be performed from 6.7 ft/2 m to meet certifications and a sensor must be able to withstand the force of such an impact as well as high levels of ambient vibration.

Sensors must also be able to minimise the effects of cross-interference, which could cause inaccurate readings and nuisance alarms. There are various compounds that can impact performance including certain alcohols when detecting H2S and these effects must be negated.

Long life sensors are a considerable advantage because they can help to extend maintenance intervals. This can have a dramatic impact on your ongoing costs and a good manufacturer will have solutions that can offer extended operational life, helping you to make future savings over the product life of your portable gas detector.

A quick response is also imperative; even when rapid concentration changes are experienced. An example is hydrocarbon cracking processes within a refinery where large levels of CO can be released and must be detected without delay.

Something that is often overlooked is the importance of repeatability; you need to be able to rely on your manufacturer’s processes and controls so that each sensor you use works exactly as it should, every time. Take a holistic approach to selecting a manufacturer and be sure that their production practices can deliver consistent high quality results.

Why Knowing What's Inside is so Important
The sensor you use is so much more than the little unseen component inside your gas detector. It's the difference between nuisance-alarms or maximised accurate detection performance; the difference between reduced ongoing device care requirements or a more frequent maintenance regime need; the difference between adaptability to changing environmental factors or an inability to perform in harsh locations. And most important of all, it's the difference between an engineer going home safe to his/her family after a hard day's work or not.

You will already be aware that the sensing technology you use protects the lives of your employees, but you may not have considered the effect it could have on your business efficiency. Make sure you provide as much consideration to the sensor in your gas detection device as you do to the device functionality itself - it save lives AND also saves money in the long run, so take the time to consider 'what's inside' YOUR' gas detector and choose wisely.