Wireless and video improve process safety
14 Dec 2009
London – Wireless communications is enabling the biggest developments in safety systems across the plant currently, allowing the simple addition of extra process alarm points or measurement data, right up to providing video surveillance across the plant, and mobile voice and computer interfacing with site staff.
The initial applications for wireless sensors tended to be for delivering information from remote or difficult locations, where the cost associated with safely installing new data cables was prohibitive, or the task challenging.
Desirable monitoring or extra safety alarms were added using wireless, because they would fit into the plant monitoring systems already available: so personnel safety showers and eyebaths are now wirelessly alarmed into plant systems, using an open/closed contact input linked to the shower valve. In the US, this was also driven by new legislation designed to improve worker safety monitoring.
Invensys, using an Apprion wireless system, was one of the first to mention this type of application, at the PPG Lake Charles site some years ago. Honeywell then quoted the use of its XYR5000 wireless transmitter on 17 emergency showers at a chemical manufacturing and refining plant, to upgrade their facilities along First Alert response guidelines, at a cost of around 10% of the alternative wired system.
These hazardous area approved transmitters work off a battery with a three-to-five year expected life. Recently, Emerson incorporated emergency shower monitoring into its system at the Boise paper mill, saving 60% of the forecast conventional wiring costs on a project monitoring eight showers.
Many of the control system suppliers promoting wireless to their process plant customers have allied with wireless and IT communications suppliers, such as Dust Networks, Zigbee, Motorola, Apprion and Cisco, to gain the best available technology and security of the networks – in the move towards a control capability.
This brings some new names to the fore as suppliers to the process industry: Apprion recently announced their wireless ION Video monitoring system, specifically developed to address the needs of process manufacturing in terms of plant safety and security. TheION Video analyzes motion, tracks, counts, and identifies objects (such as faces), and delivers video intelligence from live video streams by performing real-time video data mining.
The family of ION Applications, which also include sensors and systems for condition monitoring and asset tracking, provide manufacturing facilities with a single interface to satisfy the application requirements of safety, security, engineering, logistics, and maintenance personnel.
Integrating video with the automation system, Longwatch is providing the capability to reconstruct an incident, simultaneously using archived video, plant data from the process historian, and the actual images that were being shown on the HMI at the time. In this way they can reconstruct what happened on the plant, what the screens showed, and what the operator did about it – invaluable for checking on procedures, any operator errors, and for training.
The November/December 2009 issue of Process Engineering included articles reviewing the use of wireless location systems for Search and Rescue tasks, and also the “Empowerment of Mobile workers” using wireless field networks.
Such a Wi-Fi-based Real Time Location System (RTLS) has been implemented in Spain by Ekahau, to increase the safety for workers in an underground tunnel project in Vigo, Galicia, where Fomento de Construcciones Y Contratas SA and ACCIONA SA are excavating 2 tunnels both 8 kilometers (5 miles) in length.
The Ekahau system provides both real-time location of the worker in case of an emergency, and also two-way communication with the workers in the tunnel, through the text messaging capability built into the badge carried by each worker. The badge enables workers to call for help by pulling the built in emergency switch, when safety personnel and management receive the help request with location information for the incident. In Norway, Pixavi have adapted this Ekahau wireless RTLS and applied the system throughout the Statoilhydro onshore and offshore installations, using existing WiFi networks.
