Wireless Transmitters In Process Measurement and Control

Opportunities for cost effective wireless process control
connections are everywhere

In process control, different devices produce signals which represent flow, temperature, pressure, and other measurable elements of the control process. In order to travel from the measurement point to the point of decision, also known as the controller, systems have traditionally relied on wires. More recently, wireless networks used in industry have evolved, especially since point-to-point systems were introduced to process environments. The standard operating procedure today is known as the Wireless HART™ protocol, which features the same hallmarks of control and diagnostics featured in wired systems without an accompanying wire.

Wireless devices and wired devices can cohabitate the same network. The installation costs of wireless networks is vastly lower than wired networks due to the fact wireless networks need much less hardware. Wireless networks are also more efficient than their wired peers in regards to auxiliary measurements, involving measurement of substances at several points. Adding robustness to wireless, self-organizing networks is easy, because when new wireless components are introduced to a network, they can link to the existing network without needing to be reconfigured manually. Gateways can accommodate between 50 and 100 devices, allowing a very elastic range for expansion.

In a coal fired plant, plant operators walk a tightrope in monitoring multiple elements of the process. They calibrate limestone feed rates in conjunction with desulfurization systems, using target values determined experientially. The difficult process environment results from elevated slurry temperatures, and the associated pH sensors can only last for so long under such conditions. Thanks to the expandability of wireless transmitters, the incremental cost is reduced thanks to the flexibility of installation of new measurement loops. In regards to maintenance, the status of wireless devices are consistently transmitted alongside the process variables. Fewer manual checks are needed, and preventative measures are infrequent compared to wired networks. The minimization of overtime and staff instruction correlates with a maintenance of precise process control.

Time Synchronized Mesh Protocol (TSMP) ensures perfect timing for individual transmissions, which lets every transmitter’s radio and processor ‘rest’ between either sending or receiving a transmission. To compensate for the lack of a physical wire, in terms of security, wireless networks are equipped with a combination of authentication, encryption, verification, and key management. The amalgamation of those fail-safes makes for the security of wireless networks equal to that of a wired system. The multilayered approach, anchored by gateway key-management, presents a defense sequence. Thanks to the advancements in modern field networking technology, interference due to noise from other networks has been minimized to the point of being a rare concern. Even with the rarity, fail-safes are included in Wireless HART™.

All security functions are handled by the network autonomously, meaning manual configuration is unnecessary. In addition to process control environments, power plants will typically use two simultaneous wireless networks. Transmitters allow both safety showers and eyewash stations to trigger an alarm at the point of control when activated. Thanks to reduced cost, and their ease of applicability in environments challenging to wired systems, along with their developed performance and security, wireless instrumentation is altering process control environment monitoring for the better.

Analynk Wireless specializes in making wireless connections among process measurement and control equipment in the industrial arena.

Standalone Process Temperature Controllers

The regulation of temperature is a common operation throughout many facets of modern life. Environmental control in commercial, industrial, and institutional buildings, even residential spaces, uses the regulation of temperature as the primary measure of successful operation. There are also countless applications for the control of temperature found throughout manufacturing, processing, and research. Everywhere that temperature needs to be regulated, a device or method is needed that will control the delivery of a heating or cooling means.

For industrial process applications, the temperature control function is found in two basic forms. It can reside as an operational feature within a programmable logic controller or other centralized process control device or system. Another form is a standalone process temperature controller, with self-contained input, output, processing, and user interface. Depending upon the needs of the application, one may have an advantage over the other. The evolution of both forms, integrated and standalone, has resulted in each offering consistently greater levels of functionality.

There are two basic means of temperature control, regardless of the actual device used. Open loop control delivers a predetermined amount of output action without regard to the process condition. Its simplicity makes open loop control economical. Best applications for this type of control action are processes that are well understood and that can tolerate a potentially wide variation in temperature. A change in the process condition will not be detected, or responded to, by open loop control. The second temperature control method, and the one most employed for industrial process control, is closed loop.

Closed loop control relies on an input that represents the process condition, an algorithm or internal mechanical means to produce an output action related to the process condition, and some type of output device that delivers the output action. Closed loop controllers require less process knowledge on the part of the operator than open loop to regulate temperature. The controllers rely on the internal processing and comparison of input (process temperature) to a setpoint value. The difference between the two is the deviation or error.  Generally, a greater error will produce a greater change in the output of the controller, delivering more heating or cooling to the process and driving the process temperature toward the setpoint.

A standalone temperature controller can fulfill multiple functions. In addition to controlling the target process temperature, controllers can be configured with data logging, alarm outputs, programmed changes to setpoints, auxiliary outputs for on/off functions, and a detailed HMI to provide data entry or a display of the process condition. Locating the controller near the process can be useful when technicians or operators need to monitor the process or effect a change in the controller setpoint. Local controllers can be connected via wired or wireless communications to other monitoring and control devices. Wireless communications are easily accomplished using Analynk's transmitters and receivers to cover distances from inches to miles.

The current product offering for standalone closed loop temperature controllers ranges from very simple on/off regulators to highly developed products with multiple inputs and outputs, as well as many auxiliary functions and communications. The range of product features almost assures a unit is available for every application. Evaluating the staggering range of products available and producing a good match between process requirements and product capabilities can be facilitated by reaching out to a process control products specialist. Combine your own process knowledge and experience with their product application expertise to develop effective solution options.

Analynk's Newest Wireless Access Point Enclosure for Hazardous Areas

New Model AP-621
Hazardous Area Wireless
Access Point Enclosure

Analynk Wireless has added again to its line of wireless access point enclosures for hazardous industrial locations. The access point enclosures are specifically targeted and designed to house specific wireless access points from a range of manufacturers, facilitating easy installation. Every model is provided with UL listed explosion proof antennas, a mounting bracket designed for the access point equipment, and RF cables to make the antenna connections. Enclosures have penetrations specifically located to accommodate the specified access point. Models are included to house a range of units from Symbol, Cisco, Meru, Aruba, HP, and Motorola, with more models added regularly to accommodate additional wireless access points.

The most recent addition is the model AP621 which accomodates  the Aruba AP-214 dual band access point. Analynk Wireless specializes in industrial wireless communications. Your wireless communication challenges are welcome at Analynk, so make contact and share your requirements. Combining your process expertise with Analynk's product specialization will produce an effective solution.

The datasheet for the new model is provided below. You can see all the models and their companion access points on the Analynk site.

Hazardous Area Wireless Access Point Enclosure from Analynk Wireless, LLC

Severe Service Valves

Careful matching of process valves to intended use
results in better and longer service

Industrial process control applications can be associated with some very stringent and challenging performance requirements for the physical equipment and components that are part of the process chain. In fluid based operations, the control and shutoff valves can be a significant impact point of extreme fluid conditions, requiring careful design and selection consideration to assure proper performance and safety levels are predictably maintained.

Industrial valves that are intended for application at the extremes are generally referred to as severe service valves. While there are plenty of published and accepted standards for industrial valves, one does not exist to precisely define a severe service valve. There is, however, some movement toward the development of severe service standards in some industry segments.

So, how do you know when to focus valve selection activities on severe service valves, as opposed to general purpose valves? There are a number of basic criteria that might point you in that direction:

• Very extreme media or environmental temperature
• High pressure drop operation that may cause cavitation
• Rapid and extreme changes to inlet pressure
• Certain types or amounts of solids contained in the fluid
• High number of mechanical operations
• Thermal cycling

Certainly, any of these criteria might be found in an application serviceable by a general purpose valve, but their presence should be an indicator that a closer assessment of the fluid conditions and commensurate valve requirements is in order. The key element for a process stakeholder is to recognize when conditions are in evidence that might overrun the capabilities of a general purpose valve, leading to premature failure in control performance or catastrophic failure that produces an unsafe condition. Once the possibility of a severe service condition is identified, a careful analysis of the possible operating conditions will reveal the performance requirements for the valve.

There are numerous manufacturers of severe service valves, each seeming to concentrate on a particular niche. You can always get more information, or discuss your special requirements, with a valve specialist. They have access to technical resources that can help with selecting the right valve configuration to meet your severe service applications.

Analynk Wireless designs and manufactures equipment that establishes wireless connections among process measurement and control devices.

Wireless Temperature Monitoring System Assures Safety in Firefighter Training Facility

Firefighters training at a burn building
Courtesy Fire Facilities

Fire Facilities designs and manufactures live firefighting training towers and buildings, referred to as burn buildings. Firefighters train in these structures honing their personal skills and developing team strategies for combating fires under live burn conditions. The training, because of the live fire in the structure, can be dangerous. Procedures and equipment are in place to minimize the risk posed to the training professionals.

Analynk Wireless designed and manufactures part of the safety and monitoring system for the Fire Facilities training structures. The system is suitable for worldwide use, as are the training structures. Sixteen temperature monitoring locations are established in the structure and monitored using the pyrometer developed by Analynk. The monitoring station provides alarm notification if the temperature in any of the monitored zones exceeds the level at which trainees can safely enter the area.

• Monitor up to 16 channels of thermocouple input
• Local temperature display on touchscreen HMI
• Audible and flashing local alarm, plus relay contacts for connection of external devices
• WiFi connection to smart phone or tablet for remote viewing of all operating information
• Data logging of each channel to USB drive
• Cloud connection for view access from anywhere with an internet connection
• Email and text alerts
• Monitoring station has NEMA 4 rating and is suitable for installation and operation in environments to -40 degrees

The Fire Facilities Pyrometer is another example of Analynk's capabilities in designing and building engineered products for specific applications. Share your process control product development challenges with the experienced professionals at Analynk, combining your concept with their design and engineering expertise to develop top flight product solutions.

Case Study From CSB - Industrial Plant Heat Exchanger Failure

Shell and tube heat exchangers at industrial plant

Industrial accidents, whether minor or catastrophic, can serve as sources of learning when analyzed and studied. Operators, owners, and technicians involved with industrial chemical operations have a degree of moral, ethical, and legal responsibility to conduct work in a reasonably and predictably safe manner without endangering personnel, property, or the environment. Part of a diligent safety culture should include reviewing industrial accidents at other facilities. There is much to learn from these unfortunate events, even when they happen in an industry that may seem somewhat removed from our own.

The U.S. Chemical Safety Board, or CSB, is an independent federal agency that investigates industrial chemical accidents. Below, find one of their video reenactments and analysis of an explosion that occurred at a Louisiana chemical processing plant in 2013. A portion of the reenactment shows how a few seemingly innocuous oversights can combine with other unrecognized conditions that result in a major conflagration.

Check out the video and sharpen your sense of awareness for potential trouble spots in your own operation.

Industrial Wireless Communications Using a Single Transmitter and Multiple Receivers

Water treatment plant

In planning a wireless installation for connecting process measurement instruments and equipment to monitoring and control stations, keep in mind that it is not necessary to maintain a one-to-one relationship among receivers and transmitters. A transmitter broadcasts the process signal on a designated channel. All the receiving devices set to that channel will receive the 256 bit encrypted signal. Each can decrypt the signal and convert the value to a common industrial analog signal for use as needed. The key takeaway is to recognize that once the process signal is transmitted, you have the ability to receive and use the signal anywhere within range of the transmitter. Effective range can extend from a few feet to several miles.

The beneficial applications for industrial wireless are limited only by your imagination and ingenuity. Share your ideas and challenges with the industrial wireless experts at Analynk, combining your own process knowledge with their application expertise to develop an effective solution.