Protecting your workers wirelessly

Wednesday, 12 June, 2013

If staff are a company’s greatest asset, then it is in the interests of that company to keep them safe and productive. There are obvious forms of protection such as guardrails and automatic machine cut-offs but more sophisticated technology is increasingly being used to address workplace health and safety issues, particularly in industries such as oil and gas, mining and utilities where employees are often working in hazardous and remote locations.

Accident investigations reveal that human error results in 70-90% of all industrial accidents. While some of these incidents are a result of pure human failure such as disregarding working procedures, the potential for error can be reduced or eliminated using wireless automation, thereby creating a safer working environment.

Wireless technology can improve accuracy and productivity by automating tasks and reducing exposure to hazardous situations. The less time workers spend in the field taking measurements or carrying out inspections, the safer they are going to be. So, wireless technology can be used to remotely monitor many of these tasks to improve overall plant safety and efficiency. Using WirelessHART technology, manual tasks, such as finding and reading gauges, can be minimised. By replacing gauges and meters with wireless transmitters for pressure, temperature, level, flow and many others, readings can be measured wirelessly then transmitted back to the control and asset management systems. Data can be transmitted as often as required by each application. This eliminates the need for technicians to make ‘clipboard rounds’ and improves the timeliness, accuracy and frequency of measurements, enabling troubleshooting and corrective action before a potential problem grows.

Assisting workers

Wi-Fi is the other major wireless technology and is more frequently used to assist personnel and ensure workers in the field are equipped with the right information at the right time. For instance, inexperienced workers are more likely to suffer harm but with fewer workers now available in some plants and the increasing retirement of experienced workers, job scopes for an inexperienced individual worker have increased and this can lead to potential errors.

When personnel are working in the field, they can have confidence knowing people with greater experience at a central location are easily contactable through a wearable videoconferencing system. By pointing a hands-free camera at a problematic piece of equipment, for example, a Wi-Fi radio link is used to involve the more experienced technician who can probably solve the problem.

Technicians often need to juggle many tasks in the plant: calibrating or troubleshooting in the field, observing field conditions and recording measurements in hazardous classified areas. With Wi-Fi radio infrastructure in place, these tasks can be considerably simplified. For example, armed with a tablet computer with video and voice capability, one operator can easily perform multiple jobs in a single operator round. These tasks may include visual inspections, taking pictures of safety hazards such as a leak on the pipeline, observing measurement of the manual gauges that, for example, may monitor flow to prevent any overflow, etc. This live information (data, video, voice, etc) is fed back through the wireless system to a central point where it can be compared with the previous day’s records, retrieved from a central server.

Workers operating in the field are faced with unique safety issues that must be managed. If something does go wrong, the results can be life threatening as help can sometimes be a long way off and communication may be limited. Wireless incident tracking solutions can be used to activate an alarm at a central point when a particular safety station, such as an eyewash or shower, has been used. This allows the operator to quickly dispatch assistance and investigate injuries. For example, using a wireless transmitter installed at each safety shower station, along with a centrally located gateway. The wireless transmitter is intrinsically safe, enabling use in a hazardous location.

In a recent application at a paper mill in North America, eyewash and safety shower stations needed to be monitored in the process safety management areas. The mill wanted its operators to be able to respond quickly to emergencies in these areas. A traditional wired solution was cost prohibitive, so an alternative wireless solution was explored.

The paper mill installed five wireless discrete transmitters at its site, which were connected to the eyewash and safety shower stations. A wireless gateway was also mounted on top of its five-storey building. The mill is now able to monitor the switches every 15 seconds and has the capability to timestamp the devices to ensure each one is updating properly. Not only did this improve the overall safety of the mill, but by using a wireless solution versus a traditional wired solution, the mill was able to save nearly 60% in installation costs.

Tracking workers

Government regulations require hazardous sites, specifically extraction sites for oil, gas and mining, to plan for emergencies. Government agencies such as MSHA (US), ATEX 137 (UK), DSEAR (UK) and Australian Emergency Management require site evacuation plans and regularly scheduled drills to plan for emergencies.

Wireless tracking solutions can be used in emergency situations so that instead of taking a time-consuming roll call, the mustering status of all personnel in the process plant can be automatically determined and located. In an emergency, having accurate location information of all plant personnel means those first responders can be immediately sent to the location of an injured person.

Plant personnel can be tracked throughout the plant site using different types of radio technology, depending on the site’s requirements. Wi-Fi-based active RFID technology uses standard Wi-Fi (802.11) radio, and that works with standard Wi-Fi equipment such as hazardous zone 2 certified access points to provide real-time people tracking.

Intrinsically safe Wi-Fi tags which are carried by all personnel, contractors and visitors in the plant send out a Wi-Fi message to the nearby access points on a recurring basis. These points then measure the signal using the received signal strength indication (RSSI) or time difference of arrival (TDOA) method and details are sent to a mobility services engine, which is a platform that enables the wireless network to deliver all the location information in a centralised and scalable way to determine the location of the tag worn by an individual. A web-based software platform can provide a full range of applications with visualisation, reporting, management and automated alerting options, as well as the ability to deliver the information to third-party systems such as enterprise resource planning (ERP) software and asset management systems through an Open API (application programming interface).

If in distress, workers can press the tag’s panic button, and if a person is not in motion for a period of time, the tag will automatically send an alert to the system. The other personnel can then respond to the incident without delay as the alert will include precise details of the person and his/her location.

Hazardous areas can also be monitored to provide a form of access control, thus minimising the risk of an incident from occurring. Only trained or authorised personnel will be permitted to enter the premises using their tags and instant alerts are given when employees and visitors enter restricted areas. Workers’ locations can be monitored in real time and reports provide accurate location data and event history.

At a coal mine in Australia, 200 workers underground were tracked, based on intrinsically safe tags in 50 diesel vehicles throughout the mine. The solution ensured that all workers in the mine were quickly and accurately accounted for at specific mustering points.

The accurate real-time location of each of these diesel vehicles also facilitates better fleet management and streamlines vehicle access into ventilation districts.

At mine sites, Wi-Fi RFID technology can be integrated into cap lamps to bring a greater level of safety to miners without encumbering them with additional equipment. Underground workers will always have their cap lamps with them, so it makes sense to use that same equipment to enable quicker emergency response and to automate the mustering process.

The technology

Wireless technology helps eliminate conventional wiring complexity. All wireless devices can be installed and commissioned within minutes and users can easily add additional devices to their wireless network.

The WirelessHART standard (IEC62591) and the Wi-Fi Standard (IEEE802.11) are both internationally recognised standards. These wireless technologies give a seamless extension of the wired architecture in the process industry. WirelessHART is built on the HART standard providing a cost-effective, simple, reliable and secure way to deploy new measurement and non-critical control points without the wiring costs.

IEEE 802.11, commonly known as Wi-Fi, provides a wireless infrastructure for fast transmission of data (voice, video, field data, tracking data, etc) over some distances. Wi-Fi also enables the wireless communication between a WirelessHART gateway and a distributed control system (DCS), and the wireless communication of remote DCS units.

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