Wireless Gas Monitoring : Application in Temporary situations & Operating Issues

Application in Temporary Situation

In some cases it may be necessary to monitor gas in situations in which the cost of setting up a wired solution is completely unfeasible. A planned maintenance turnaround, for example, might involve activities which could potentially introduce gas leaks into the area. A wireless system could be deployed during such operations and relocated once the shutdown is complete. Other temporary situations might include the aftermath of a natural disaster, a security breach or a plant expansion project.

Asset management
The ability to deploy multiple sensors wirelessly can also provide predictive and preventive maintenance capabilities that wired systems cannot provide cost-effectively. Measuring the amount of background hydrogen sulfide and methane in the air and comparing it over time trends can detect an early indication of a problem. The sensor would pick up on this and send it to an asset management application, which might track increases in methane and/or H2S and compare it to other areas, and historical norms. Analysis of changes could reveal potential dangerous trends early enough so that they can be corrected. Maintenance can be dispatched to affected areas for detailed investigation and needed repair in lieu of checking everywhere during routine maintenance rounds. For systems carrying risk of gas leakage, wireless technology can be the heart of a cost-effective reliability-centered maintenance program.

Operating issues
In addition to the basic sensing technology, battery life and inter-connectivity represent two of the most critical operating issues that wireless gas monitoring will raise.

Battery life.

Battery life is a key variable in both the economics and performance of a wireless monitor. The more remote the location being monitored, the greater the role of the battery in maximizing safety at a low cost. Newer systems use lithium metal technology which, combined with low-power components and advanced power modules, can extend life well beyond 5 years, significantly greater than current offerings operating under the same conditions. Affecting battery life in addition to its metallic composition, is how well low-power components like display and sensory assemblies feed the circuit board, how often they are pinged for a message, and the speed at which the message is transmitted. A typical gas monitor could be configured to send readings at any interval, from seconds to hours or more, depending on the need for information and the desired battery life and the speed at which the sensor can actually collect data. Furthermore, prudent wireless network design (how the wireless sensors are laid out) should be considered, and can help to maximize battery life.

Interconnectivity

Your plant IT personnel will need to be involved in the deployment of a wireless gas monitoring system in order to connect the wireless network to plant monitoring and control systems. They will need to know exactly how the device will join their network and how it is communicating data, which is a function of the communications protocols.

How the system ties into the control system depends on the wireless protocol selected. A device supporting WirelessHART, for example, would automatically join an existing HART network, which is the most commonly deployed protocol. WirelessHART is a globally approved standard (IEC 62591) that promotes an interoperable, self-organizing and healing, mesh technology, which is secure, reliable, and easy to use (Figure 2). A communication protocol like this can improve reliability by enabling the signals to find the best signal paths to deliver rich diagnostic information about the gas detector. In addition to communicating gas concentration values in PPMs and %LELs, a WirelessHART enabled gas detectors can also transmit information on battery life, temperature and date of last calibration.

Figure 2

In our next and concluding post in the Wireless Gas Monitoring series, we will explore the WirelessHART protocol. Stay tuned!

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Wireless Gas Monitoring : Applications

Unlike wired gas detection systems, which have expensive infrastructure requirements, wireless systems can be deployed just about anywhere there is a potential for a gas leak. The most likely applications include remote and local detection, temporary situations and monitoring to improve asset management.

Wireless remote and local gas detection: Tank farms, oil and gas production facilities, refineries, pipelines, abandoned wells and waste treatment plants are all good candidates for wireless gas detection.

Tank farms :Storage tanks are one of the most common sources of gas leaks. They are always located some distance from the central facility and sometimes near residential areas. If the wind is blowing away from any wired detectors onsite, for example, plant operators may not know of any leaks until residents call in complaining about the smell. Multiple sensors could cover more tanks, and they could all be networked through a common gateway.

Top view of tanks on factory

Oil and gas production facilities and refineries: Wireless monitors can provide additional protection for workers in refineries. If the wired detection system is not up to current standards and/or lacking coverage due to plant expansions, the workers and the community may be at risk. A typical inside the plant application might include setting a local field mounted PLC to operate a ventilation system or shutdown routine based on a signal from the wireless monitor.

Pipelines: The pipelines that transport hydrocarbon products to and from wells, tanks, and processing and storage facilities are another common source of leakage. Breaches at these  facilities are quite prevalent today. The pumps, valves, couplings, flanges, pipes and other trappings surrounding the piping are all vulnerable to age, installation errors and trauma. Some of these components are underground, so finding them is even more difficult. With hundreds of miles of pipes, it’s impractical to deploy thousands of local pipe leak detection devices necessary to cover the leaks within pipes.Gas industry, underground gas storage facilities

Plugged and abandoned wells: Capping an abandoned well in concrete does not guarantee that it won’t leak, but because it is not operating, no one is around to notice problems and there is little incentive to invest in wired detectors. But leakage could result in risk to the area, fines and other problems and an easily deployed wireless solution could be very valuable.

Wastewater treatment plants: Pollution control is another area rife for improved gas monitoring. Waste produces methane which is highly combustible but few municipalities have the resources to devote to wiring up waste locations. Yet the risk is significant and can be mitigated with the installation of inexpensive wireless monitors on anaerobic digester tanks, solids landfill or other vulnerable points.

In our next post, we will explore the applications of the wireless device in temporary situations. Stay tuned!

 

by: Wil Chin, Vice President of Marketing and Business Development at United Electric Controls

Joe Mancini, Senior Product Manager at United Electric Controls

Greg LaFramboise, Retired Wireless Technology Lead, Chevron

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Wireless Gas Monitoring : The wireless connection

Wireless technology removes the physical and economic barriers associated with wired gas detection devices. It can save up to 90 percent of installed cost and time and can be applied in both field and plant networks, detecting leaks that might not otherwise be detected by sparsely distributed wired units. Just about any type of wired sensing technology can be adapted for wireless and some incorporate multiple capabilities, combining both IR and electrochemical for example. At the sensor level, there is little difference in the basic technology deployed between a wired and a wireless gas detector.

However, using sensors designed for wired gas detectors in a true wireless (no power and signal wires) application, would be impractical as batteries would require replacement in months instead of years. Figure 1 shows the exterior of a wireless gas detector with all of the built in protections necessary for deployment in inside and outside hazardous area locations. It shows the antenna by which it communicates with its host. The housing should be rated Class 1 Div 1 explosion proof, and there should be a graphic display that shows gas concentration, network, calibration, temperature and battery status. Accessible field connection points should be rated intrinsically safe for Zone 1, allowing connection to a hand-held communicator for configuration and testing as well as for swapping out sensor types without a hot permit.

Figure 1

Once the sensor takes the measurement, the wireless devices send signals to a wireless
gateway which can be connected to a fire &gas control system, distributed control systems (DCS) or programmable logic controller (PLC) host for processing. The wireless signals may be designed using any network protocol, although, as will be discussed later, standard open protocols such as Wireless HART have specific advantages.

In our next post, we will explore the applications of the wireless device. Stay tuned!

 

by: Wil Chin, Vice President of Marketing and Business Development at United Electric Controls

Joe Mancini, Senior Product Manager at United Electric Controls

Greg LaFramboise, Retired Wireless Technology Lead, Chevron

 

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Wireless Gas Monitoring : Gas detection system architecture

Gas detection is a power-hungry operation, so the main system must be wired to a power source. The cost of such systems, including the cost of planning, design and running conduits for power and signal wires, trenching, and other installation details, can be in the neighborhood of $10,000 per device. Gas detection systems covering all critical plant points have traditionally been specified at the front end engineering and design (FEED) of the plant design, but coverage for all possible points is typically not financially feasible. Furthermore, most of the legacy gas detection systems in use today were specified prior to plant expansions and increased safety awareness. However, as significant incidents and new standards drive heightened interest in plant safety, and as plant systems age and experienced workers leave the workforce, there is a need for tighter monitoring of gas leaks. Filling this need with wired sensors is prohibitive, not only because of the wiring expense, but for many sites, because there is minimal workable space to add wiring or other necessary infrastructure.

Personal or wearable gas detectors can provide a layer of protection, but the accuracy of these devices is poor with 20-25% accuracy as reported by experts in a recent National Fire Protection Association (NFPA) conference. NFPA speakers highly recommend augmenting of personal devices with more reliable fixed gas detectors in potentially dangerous areas. Installing fixed detectors, would better warn workers against entering dangerous areas, protecting them from harm. Regardless of whether a company is deploying fixed or personal detectors, the detectors should be networked so workers in the vicinity are aware of the hazardous condition.

In our next post, we will explore the wireless connection function and how this technology removes the physical and economic barriers associated with wired gas detection devices.

by: Wil Chin, Vice President of Marketing and Business Development at United Electric Controls

Joe Mancini, Senior Product Manager at United Electric Controls

Greg LaFramboise, Retired Wireless Technology Lead, Chevron

 

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Wireless Gas Monitoring : The emerging solution for improving plant safety.

Industrial processes such as oil and gas production facilities, refining, chemical production and power generation often involve toxic and combustible gases, which can create serious hazards if they escape into the air. Toxic hydrogen sulfide (H2S) and combustible methane (CH4) are among the most widely produced and most dangerous industrial gases.

To minimize risk to personnel and plant safety, plants often deploy early warning devices such as gas detection systems, which require expensive infrastructure and seldom cover all of the potential leak points. This concern is driving a trend toward augmenting existing wired gas detection coverage with wireless sensors, which can significantly increase monitoring coverage with minimal new financial outlay.

In this blog series on wireless gas monitoring, we explore this emerging solution for improving plant safety and kick off by taking a look at some gas sensor basics. In the subsequent posts, we will describe gas detection system architecture, applications of wireless gas monitoring and explore some operating issues that wireless gas monitoring may raise.

Gas sensor basics

A typical gas detector identifies and monitors gas leaks, outputting an electronic signal such as a 4-20 mA, HART, or Modbus wired signal, to a dedicated fire & gas (F&G) system, controller, PLC or control room which sets alarms or guides corrective action. For toxic gases, those signals represent the presence of gas in parts per million (PPMs). For combustible gases they represent the percent of the the lower explosive limits (LELs).

A number of technologies are used to detect the presence of gases. Infrared (IR) technology, which is among the most commonly deployed, monitors gas concentration based on the principle of infrared absorption. Gases like methane absorb specific infrared wavelengths. The electronics module computes the gas concentration based on the amount of absorption.

Electrochemical sensing, another commonly applied technology, measures the concentration of a target gas by reacting with the gas and producing an electrical signal proportional to the gas concentration. A typical electrochemical sensor consists of a sensing electrode and a reference electrode separated by a layer of electrolyte.

Sensing technologies vary in reliability, depending on the properties they are measuring and on the types of gases involved. Electrochemical detectors, for example, tend to be more reliable for specific gases, like hydrogen sulfide, but may lose effectiveness after continuous exposure. Infrared technologies on the other hand tend to be more reliable for detecting LELs and may perform well for up to five years or more. In addition to the sensors deployed in gas detectors, a detection system typically includes a controller or a plantwide fire & gas control system with HMIs, alarm systems, and relays connecting to valves, pumps, or whatever final element might be needed to suppress a gas leak and/or HVAC and fire suppression systems to suppress a fire.

In our next post, we will zoom a level out and examine how a gas sensor is fitted to a typical detector and how that detector plays a part in a gas detection system architecture.

 

by: Wil Chin, Vice President of Marketing and Business Development at United Electric Controls

Joe Mancini, Senior Product Manager at United Electric Controls

Greg LaFramboise, Retired Wireless Technology Lead, Chevron

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Mechanical Switch Upgrades Made Easy

When considering upgrading the electro-mechanical switches that have been in service for many years, the task can seem daunting. These 2-wire alarm and shutdown devices have served the plant well for many years. Many of the switches have been in service for more than 15 years without failure. But these switches are blind (lack self diagnostics) and are difficult to calibrate.

Process transmitters seem like the obvious choice to replace these switches. Transmitters include diagnostics and don’t require calibration inspections as often as their mechanical brethren. But replacing a mechanical switch with a transmitter is overkill. The unit cost of a mechanical switch versus a process transmitter has a differential of 1.5 – 2 times the original cost of the switch. On top of that, there is wiring, analog inputs and control schemes to consider. And because the plant was built in the 1970s, there are switches everywhere!

Where does the One Series 2-Wire get its power? Directly from the digital input (DI) of the control system. By using a small amount of leakage current taken from the DI, the One Series can provide the same alarm and shutdown functionality previously provided by the mechanical switch – using the same 2 wires and unmodified control scheme.

2slpm041 (safety transmitter)

By using extremely efficient (e.g., low) power management techniques, the One Series is able to scavenge just enough current from a typical DI without tripping it and provide the same on/off switch signal formerly provided by replaced electro-mechanical switch. This patented technology allows the One Series to replace any mechanical switch that is connected to a PLC or DCS control system input and utilize the same switch control scheme and wiring.

No wiring or programming expenses. No MoC considerations – replace a switch with another switch. The cost of the upgrade is the cost of the One Series.

blog-capture

Is there an alternative? One that provides easy adjustability, self diagnostics and can operate using the existing plant wiring and control scheme? Yes! Consider replacing your electro-mechanical switches with a new breed of switch – the One Series 2-Wire electronic switch. The One Series provides IAWTM self diagnostics, configurable set point and deadband, digital process display and operates on the same 2 wires and control scheme as the old mechanical switch being replaced.

 

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Ethics and Decisions

Ethics green highlighter

In life, we are all faced with difficult decisions. Whether they are personal or professional decisions has no bearing on the level of complexity the human mind sorts through to come to a decision. And when we factor ethics into the equation, determining what the “right” thing to do can be a daunting task.

Fortunately, there are simple questions we can ask ourselves when trying to reach the right decision. In the business world, all of us need to read, understand and consider the ethics policy of the company that we work for. When faced with a business decision, the ramifications can be huge and affect a lot of people, including coworkers and the company’s customers. Here’s a simple test that we can perform to see if our proposed decision is ethically correct. Share the decision with our company’s president! If we are willing to do this, then we can rest assured that the decision is the right decision and follows the corporate ethics policy.

ethics-and-compliance

In our personal lives, we have to compare a decision we are about to make with our own personal code of ethics. What are we comfortable with? How will our decision affect other members of our family? Are the consequences of our decision worth sticking with it? Well, as you may have guessed, there’s a similar ethics test for this one, too. Share the decision with our mothers! If Mom agrees with our decision, we know intuitively that our decision is the right one.

There’s one more test we can perform to test whether a decision is ethical. This one is a blend between our personal code of ethics and the corporate ethics policy. We must ask ourselves, are we willing to talk about this decision during our next job interview? If the answer is yes, we are about to make the right decision.

If we are willing to take part in all three of these ethics tests before making tough decisions, we will have a high level of confidence that our decisions are ethical and the right thing to do.

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