Plant safety engineers take aim at a wireless future

Author : Dr.Patrick Hogan, vice president of marketing for Honeywell Analytics

20 September 2010

Equipping the mobile worker with a personal gas monitor that not only can monitor a range of hazardous gases, but also report the worker’s exact location, continuously, in real time—over a wireless communications grid—represents one small step forward for today’s control room operator, yet one giant leap forward for plant safety.

The not-so-distant future is likely to see a convergence of wireless technologies such as GPS, Bluetooth, WiFi and voice communication for location management and operator ID tracking as well as personal gas monitoring and other personal protective equipment (PPE) use.

Because there is no need to run wires or conduit in a wireless system, information from both process and safety instruments used in a refinery, petrochemical plant, wastewater treatment facility and various other manufacturing environments can now be obtained more cost effectively. This is particularly advantageous for monitoring in hard-to-reach or remote area applications.

We are on the cusp of a new era in plant operations characterized by a galaxy of sensors obtaining and transmitting information on a multitude of changing dynamics — e.g. temperature, pressure, transportation, tank levels, vibration, corrosion, gas concentration levels — over a wireless grid. The transmitters will be installed using different wiring schemes, and connected to a variety of control systems using PLCs, SCADA or DCS as well as stand-alone control systems.

Today’s plant - The problem of isolation
In this scenario, hazardous chemicals are either being used in the process or generated as by-products of it. The processes may be managed by thousands of workers in both permanent and mobile locations throughout the plant. By law, workers within the plant must carry single-gas monitors to alert them of exposure to a poisonous gas such as hydrogen sulphide or lack of oxygen. Some operators may alternatively need four-gas monitors if they work in confined spaces such as tunnels, reactor vessels and other areas where a mix of explosive and toxic gases can build up or diminish breathable oxygen levels.

In today’s busy, noisy process environment, when a personal monitor detects a dangerous gas level and goes into alarm, it may alert only the operator. Moreover, data logged within the portable unit is accessible only to the plant supervisor at the end of the shift. This happens when the operator returns to the instrument shack and places the portable in a docking station to recharge the batteries, automate the data download process and test the detector with fresh calibration gas.

In today’s typical plant there are multiple monitoring activities working in isolation and the overall hazard combination cannot be made readily apparent either to the plant supervisors in the control room, or more significantly, to the technicians working in the plant. Connections between the overall sensor inputs cannot be realized quickly enough and in many cases is not used to capture a true picture of the overall plant and personnel hazards.

Tomorrow’s plant – Better connected
In tomorrow’s plant we will see a greater deployment of wireless and hybrid wired /wireless systems that share data rapidly across the plant. The data will be aggregated into a more sophisticated assessment of the hazard to the plant and the operators.

The next generation of portable gas monitors will be able to connect wirelessly to wireless WiFi routers located around the plant and immediately share and communicate sensor data carried by hundreds of other operators into the plant’s hazard visualization overview as seen in the control room. Another feature of this integrated mesh between mobile and fixed sensor points is that the location of the operators will be depicted in a real-time mode at the supervisory level. In other words, the plant safety manager will know at all times where the combined dangers are, along with the location of all personnel.

Let’s describe a few emergency scenarios that demonstrate how much safer the plant and workers will be in this integrated sensor environment.

Effective emergency response
Should a plant worker in a trench suddenly be exposed to a dangerous level of hydrogen sulfide toxic gas, that person’s monitor will go into immediate alarm and warn the worker to get out of the trench. The gas reading, alarm level, operator ID and location will be immediately flagged on the plant SCADA system in the control room. Immediate action will be taken to alert the emergency response unit, who will go to the scene and assist with recovery or first aid needs.

Moreover, other personnel in the immediate hazard area also will be alerted automatically on the screen of their personal gas monitors (with all gas monitors connected to the intelligent plant-wide grid). Using a combination of sensor inputs (hazard levels, wind direction and other data regarding muster points in the vicinity), control room operators will be able to confidently direct workers where to exit safely. The overall outcome is the direct result of a connected safety philosophy — the person in trouble is not only made aware of the danger, but also has the appropriate support services rolling faster and more effectively. All operators are automatically accounted for by location and operator ID.

This intelligent connection between field operators and plant infrastructure also means that hazards not associated directly with a gas release (e.g. fire, leak, flood, smoke) can also be flagged with evacuation instructions to the same communication portal that the personal gas detector provides.

In addition to providing more effective hazard mitigation, real-time wireless communications will also generate plant efficiencies and cost reductions. As workers travel around the plant, their monitors will log levels of gas leakage from solvents or other gases that — while not initially dangerous — nevertheless are indicators of areas that need preventative maintenance. Service teams can be deployed to the exact location to hunt down leaking valves, corroding pipes or damaged process equipment, and they can make those repairs proactively, thereby avoiding more expensive repairs or even catastrophic failures.

Barriers to wireless adoption
Despite the rapid spread of wireless communications for industrial processes, adoption of the wireless format for life safety systems has been slow to gain a foothold. This is understandable due to the necessarily cautious, universal regard for plant safety. After all, a life safety system must be failsafe by design; and the use of wireless communications for this purpose is relatively new.

However, the life safety system of tomorrow will see a convergence of wireless technologies (WiFi, GPS, and mesh wireless) forming a multi-layered, redundant system design. Also the industrial WiFi mesh system will be made more robust, with additional levels of security added to prevent hacking or stray interference. The wireless life safety system of tomorrow will be purpose-built to the needs of the plant, putting the plant owner in full control of the system, along with plenty of signal strength and redundant back-ups.

It should also be pointed out that, in the unlikely event that the integrated communications system fails during a gas release, the gas monitor will still raise the local alarm – strobe/ buzzer/ vibration – so the operator can take evasive action without the need to be dependent on a remote action that may or may not be connected due to other environmental issues.

The user experience: A plea for simplicity
In step with the emerging sophistication of the wireless platform, gas monitors have become easier to use and increasingly unlikely to be misused.

Today, many manual tasks previously conducted by workers have become automated. Gas detector user options have been simplified, prompting the user to respond only to commands needed for day-to-day operations. Some examples:

• Many critical gas detector operations are now controlled by a personal computer so workers cannot harm themselves or their company.
• User interaction with the instrument has been simplified through button presses, including single button operation, turning a complicated device into an on-off one.
• With multiple generations of products designed using the same interface, training time has been minimised or eliminated, further simplifying safety.

One trend likely to gain widespread use is the visual compliance feature, or flashing LED on the gas monitor. Taking its cues from the airline, construction and other industries where visual technologies have become available to improve safety, users of gas detectors can now determine, from a distance, the compliance status of portable gas detectors. Low power high intensity LEDs (Light Emitting Diodes) constantly flash during normal operation and can be seen from up to 20 feet away in sunlight. In less than a second, safety managers and workers can determine correct detector functionality and its compliance status.

Visual compliance technology is emerging as the simplest, most economical way to ensure that the crew is safe, the site is compliant and the job is productive. It is likely to become a mainstay on the wireless gas monitor of the future.

To summarise then, we are on the verge of seeing gas detectors use wireless and location based telemetry, LED flash technology and other simplified operational features to provide a future roadmap of a more integrated and intelligent monitoring solution. The goal is to exploit additional functionality out of the essential gas detector platform to drive greater productivity and prevent downtime at all points in a typical worker’s shift. The overall impact to the business is a smarter, safer and more cost effective working environment — and a boost to efficiency and bottom-line profitability.

Wireless gas detection systems in use today
Honeywell Analytics, the gas monitoring instrumentation arm of Honeywell, has already proven the viability of wireless communications in life safety, with many installations of multi-point carbon monoxide/nitrogen dioxide gas monitoring systems in continuous operation in parking garages, vehicular structures and other public facilities . This gas monitoring system uses a mesh wireless topography with ‘smart’ gas detectors and transmitters operating in a self-organising design. The network automatically adapts as devices are added or removed, obstructions are encountered, or when one monitor loses power; this ‘self-healing’ characteristic is an essential feature of mesh wireless and constitutes a form of redundant safety.

For over 20 years, BW Technologies by Honeywell has deployed its Rig Rat, a solar-powered wireless mobile gas alarming device, at many oil and gas production platforms.

In addition, Honeywell has been selling industrial wireless solutions since 2002. Through the company’s OneWireless platform, hundreds of sites have optimised plant productivity and reliability, improved safety and security, and ensured regulatory compliance.