Thin Clients in Hazardous Areas.

It takes a business on average 18.5 hours to recover from a disaster such as a fire and the cost of the resulting downtime can vary between $8,000 for a small business to $700,000 for a large business. Here, Noel Sheppard a director of industrial computing specialist Distec, explains how businesses can use thin-client computing to solve the age old problem of hazardous areas.

If you thought putting a Mentos mint in a bottle of Diet Coke was explosive, you’ll not be surprised to hear that the factory that produces the infamous candy in Ohio, USA, has exploded three times since 2003. In the most recent explosion on Tuesday January 10, 2017, Cincinnati local news reported a large explosion in the area that resulted in the closure of the road outside the factory. Manufacturing was shut down for the shift and about 40 employees were evacuated. Luckily, no one was injured.

Investigations suggested that this explosion and the ones before it had been caused by large amounts of candy sugar moving through pipes and silos. The dust from the sugar generated enough static electricity to spark an explosion. Point Pleasant fire chief Mike Giordano said the explosion was so loud that firefighters heard it at the fire station before emergency calls began to come in.

It may not be immediately obvious, but according to the UK’s Health and Safety Executive (HSE), “gases, vapours, mists and dusts can all form explosive atmospheres with air. If there is enough of the substance, mixed with air, then all it needs is a source of ignition to cause an explosion”.

The HSE classifies hazardous areas into zones based on the potential risk they pose of explosion. As well as the layout of the plant and the safety procedures in place, the regulations identify potential sources of ignition such as those on a PC. Alongside these regulations, there are two European ATEX directives, namely 99/92/EC and 94/9/EC, that describe what equipment and work environment is allowed in an environment with an explosive atmosphere.

The problem is that while the regulations provide the necessary safety requirements, it can be difficult to know exactly what type of equipment will work in your plant. This means that engineers and plant managers can end up spending more time and money retrofitting standard equipment, such as industrial PCs, barcode scanners and telephone systems with measures like enclosures and insulation to make them compliant with the regulations.

However, the resulting setups are not always practical, which is why most plants working in environments with an ongoing risk of explosion use ATEX-approved PCs with embedded peripherals such as keyboard, video and mouse (KVM) inputs. The downside is that a plant might need dozens, if not more, ATEX-grade PCs, sending costs spiralling.

There is, however, a third option. An easy way of solving this problem is by using thin client computing. Popularised in the nineties, thin clients now offer a much cheaper and more practical answer for anyone looking to use industrial computers in hazardous environments.

So how does it work? Well, instead of using a fully specified industrial PC at each node, the PC is replaced with an ATEX-approved thin client, a stripped down PC with minimal hardware and software. The unit contains basic components including a processing unit and solid-state memory such as a flash drive in lieu of a conventional hard drive. All of the computing power is essentially transferred to a server located in a non-hazardous safe area, or even off site, and the user accesses the node through a remote desktop or virtual operating system.

The main benefit here is that an engineer can set up a new PC in minutes rather than hours. Equally, if anything goes wrong during use, there is no need to spend time diagnosing problems or replacing components locally, the engineer can simply replace the node quickly and send off the broken part for repair without causing downtime.

There is also the benefit of improved security. Data can be better secured behind industrial firewalls and users can benefit from better redundancy, availability and disaster recovery. Businesses also have the flexibility of using cloud computing to provide data access to the company’s other facilities.

For example, one of Distec’s customers, a consumer goods company working in the food and beverage and personal products sector, was using keyboard, video and mouse (KVM) extenders connected to a server in a safe area using coaxial cables. The typical cost of a hazardous-area PC in these applications can run in the region of £12,000 per node compared to £6,000 per node for a thin client.

In this application, Distec provided VisuNet thin clients from Pepperl+Fuchs. Connected using Ethernet cables, the thin client provides remote access from the server so the user can configure, maintain, monitor, support and perform firmware updates on the entire fleet from a centralised location.

The Pepperl+Fuchs system also offers true industry 4.0 compatibility. Engineers can use the remote monitoring function to see the status of the system right down to each sensor in the production process; configuring, commissioning and maintaining the hardware using a restricted web browser. Combine this with an enhanced write filter (EWF) mechanism, a built in firewall, USB lockdown and an auto-connect feature, it’s easy to see why thin client computing can allow engineers in hazardous environments to achieve more with less.

There is a lot of pressure on plant managers to improve their plant’s performance while maintaining uptime and security. The traditional role of industrial PCs is changing and businesses should now seriously consider thin client computing as a safer and more flexible alternative to industrial PCs in hazardous environments. Perhaps then, our factories can be less explosive than our Mentos mints.

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