Process Control Methods: On/Off Control

Telmar Alarm/Limit Controller

Many athletes are familiar with the term “turning it on” or “turning it up,” typically in reference to a great performance or improvement in play. “They really turned it on in the second half” or “They turned it on in the third quarter.” The frustrating part for those athletes, though, is that they sometimes cannot control when the magic happens. Sure, they can train well to put themselves in positions to have great games, but very few athletes have the ability to flip a switch and ‘turn it on’ by command; those who possess anything close to controllable magic may go down as some of the best to ever play their respective sport.

Thankfully, in the world of process control, a system exists where it is possible for a control element to be determined by either being turned on or off: on/off control theory is based on the idea that there are two positions for a specific control element, i.e. open or closed. The lack of a middle-ground position may sound absolutist at first, and it’s not the most complex method employed by process controllers, but there are distinct advantages to the on/off system. For example, on/off control is often used industrially; however, basic home appliances such as fridges and ovens both utilize on/off control. The oven and the fridge are both used for straightforward purposes, matching the control method – such is why on/off control is not very popular for use in a commercial setting requiring a wide range of complexity. Another prime example of on/off control is a heating system, where, when the house gets cold, the heater turns on, and when the house reaches a certain temperature, the heater turns off. The process variable, in this case the temperature, is determined by the output, meaning that when the output crosses a certain threshold, the change occurs in the system being switched from either on to off, or off to on.

Due to the aforementioned nature of the controlled output being either 100% or 0%, this method of control is not the best for every application. One of the most common uses for on/off control relates to HVAC systems, where maximum output is being delivered or the system is off. To prevent nearly constant oscillation between the desired temperature and the range either above or below, a staple of on/off control oriented processes is the deadband. A deadband is essentially the process control equivalent to a demilitarized zone, a designed neutral space where no change in the output signal occurs. Let’s say the heating thermostat in a house has a setpoint of 65°F. If the deadband range of the thermostat is 4°F, the furnace will start when the measured air temperature is 61°F (65 minus 4). The furnace will run until the air temperature reaches 65°F. The deadband, depending on the capability of the controller, can sometimes be repositioned in relation to the setpoint, but the key function of deadband remains the same. No change in controller output state occurs while the process variable, in this case room temperature, is in the deadband. This keeps machinery from rapidly cycling on and off, with resulting excess wear and tear or other negative consequences. The deadband compensates for the disadvantage of such an on/off control system in terms of absolution. Another process which illustrates on/off control is a liquid tank filling operation. When liquid in a tank reaches a certain level, level sensors and switches exist which, upon sensing the liquid  at a predetermined level, will send a signal to a controller, causing a fill valve to close or pump to cease operation.

The same elements which make on/off control appealing and compatible with some processes also render some disadvantages when applied in other scenarios. The aforementioned rapid cycling may have been somewhat corrected thanks to the theory and implementation of the deadband, but issues relating to the black-and-white operational principle also provide a potential drawback in different systems. A delay with a time value greater than zero exists in a good amount of practical on/off control situations where ‘dead time’ impacts the time it takes for an on/off position to switch. This means the value thresholds established for each position may be crossed before the opposing position kicks in to bring the value back to within the intended control range. For processes requiring strict value limits to be maintained with little or no margin for error, this particular truth of on/off control is extremely hard to ignore. Also, systems which are working together to form a more complex, connected process are rarely used in conjunction with on/off control because when the oscillations in on/off controlled systems occur – especially in processes where deadbands are inapplicable – they could ricochet through the connected system and introduce unforeseen complications and process instability. The ‘overshooting’ of the element being controlled is a common risk to consider when evaluating the potential disadvantages of on/off systems, causing them to be typically incompatible with environments where precise regulation is required. That said, the relatively low cost and simplicity of this process control method makes on/off control a rugged and long-lasting choice for systems which can function well within the limitations of the controller.

Properly applied, on/off control methodology can provide an inexpensive and effective solution that is easy to apply and maintain. Analynk, under their Telmar brand name, manufactures numerous analog devices that can be applied in a process control application. Share your process control challenges with product application specialists, leveraging your own experience and knowledge with their product application expertise to develop effective solutions.

Overcoming Signal Attenuation in Industrial Wireless Transmission

Wireless signals facilitate mobile and remote connections
of industrial process measurement and control equipment

Wireless connections for process measurement and control devices continue to grow in their application range and adoption. The ease with which remote, mobile, even nearby devices and equipment can be connected to monitoring and control stations keeps wireless connectivity a considered option for many facility modifications and additions.

How do you know if the wireless connection you intend to establish will work? It's not a question of whether the gear will function properly, but one of whether the signal will be able to find its way from point A to point B. Signal attenuation is the reduction in signal strength that occurs along the path between two points. Too much attenuation and the signal is not effective in delivering data to the destination. Two main elements contribute to signal attenuation.

Distance

Radio signals deteriorate over the distance traveled. This attenuating factor can be overcome by boosting transmission power, but regulatory limits are in place that disallow much in the way of increasing transmission power. Keeping in mind that signal attenuation at a level that renders a transmission indecipherable, just caused by distance alone, requires a very substantial distance. That said, there are several effective solutions that can be put in place. One involves increasing the height of the transmission antenna. Another is to install a repeater at a point along the transmission path. A repeater, properly placed, will effectively receive the signal from the transmitter, then transmit a new signal of greater strength that replicates the original received data. The use of repeaters can greatly extend the distance spanned by a wireless transmission.

Obstructions

Many are familiar with the objective of establishing "line of sight" transmission paths between transmitter and receiver. Physical structures and materials of all types should be considered detrimental to the transmission of wireless signals. A basic understanding of Fresnel zones is helpful in overcoming the barriers presented by physical obstructions. As with distance, antenna height or location can be a significant factor in dealing with the challenge of obstructions. Repeaters, described earlier, can be instrumental in getting your signal over or around otherwise impassable obstructions.

Routing wireless signals presents different, but no more complicated, challenges than routing cable. The tools are different, the medium is different, but you are still just trying to find a way from point A to point B. With experience, wireless signal propagation becomes is mundane is routing conduit.

Share your industrial wireless ideas and challenges with the experts at Analynk Wireless. Analynk Wireless manufactures equipment used to establish wireless process connections across the room, across the plant site, across the highway, and around the globe.

Industrial Wireless Application: Remote Equipment Monitoring

The A16000 Expansion Module increases the I/O
capacity of a standard wireless transmitter or receiver
Image Analynk Wireless, LLC

Imagine yourself a newly hired facilities manager, the go-to person responsible for the proper and continuous performance every machine on site. One machine in particular, you are informed, is a large walk-in refrigerator that houses the primary raw material for the production operation. There is a lot riding on that machine because the stored material is useless if not kept cold. Oh, and by the way, the plant site is bisected by a public street and the refrigerator is located across the street from the main building where the facilities office is housed. Your assessment of the equipment reveals that a lone temperature alarm device monitors refrigerator temperature and sounds a loud horn if the refrigerator temperature reaches a high limit setpoint. There are no existing wire pathways between the main building and the walk-in refrigerator that are available for your use.

Clearly, the level of risk associated with the refrigerator is high. It merits implementation of an improved strategy to monitor refrigerator performance. Things under consideration include some the following items.

• A real time display of the current refrigerator temperature in the facilities management office. 
• Analysis of the temperature data for an upward or downward trend that might indicate the beginning of a malfunction of the cooling system or controls.
• Monitoring of refrigeration compressor motor current, which can be related to the temperature data to confirm that the compressor is operating when it should.
• Real time display of refrigerant suction and discharge pressures.
• Analysis of refrigerant suction and discharge pressure to identify trends or conditions that may indicate service is needed or malfunction is imminent.
• Verify the door to the refrigerator is closed.
• Monitor evaporator fan motor current to verify that all fans are operating.

The greatest challenge in this application is not the gathering of the information, nor its analysis. The difficulty, as well as a substantial cost and time constraint, is delivering the information from the point of measurement to the point of use. Analog signals for real time temperature, refrigerant pressure, and motor current can be easily derived through the addition of sensors to the equipment. The only sensors likely to require intrusive work to install are those for refrigerant pressure. Routing the measurement signals to the facilities office across the road may prove difficult.

A wired connection between the measurement location to the facilities office will require either an underground or overhead routing of cable, traversing the public road. Permission from state, county, and/or local jurisdictions may be required and present potential barriers to timely completion of the project. The cost to install the cabling will be substantial. The distance may be long enough for signal attenuation to be a concern.

The best solution, in terms of initial cost and time to completion, is to establish a dedicated wireless connection between the walk-in refrigerator and the facilities office.

 A multi-input transmitter is installed at the walk-in refrigerator. The transmitter converts digital (switch) and analog input signals into encrypted digital data and transmits in the 900 MHz band to the receiver installed in the facilities office. The receiver decrypts the received data and mirrors the original analog and digital signals at its output terminals. Wireless overcomes the barriers presented by a wired installation, allowing completion in a timely manner at substantially reduced cost.

If you can operate a walkie-talkie, you can establish industrial wireless connections between remotely located, or mobile, equipment and central monitoring locations. Share your ideas and challenges with industrial wireless experts, leveraging your own knowledge and experience with their application expertise.

Remote Monitoring of Valve Position

Battery powered industrial wireless transmitter
factory installed in hazardous area rated enclosure
with hazardous area rated antenna.

The use of a centralized control or monitoring station is prevalent throughout many industrial applications. Employing a single location as collector and processor of all available information has operational advantages. 

Operations with control valves installed at remote locations face the challenge of determining whether the valve is responding properly to control commands or the demands of the process. Older systems, and some not so old systems as well, may have in-place valves that do not provide a confirmation signal of valve position. Many products are available for retrofitting this capability to a wide range of existing valves, but the challenge of delivering the valve position signal to the control center remains. It is unlikely that spare signal cable conductors were installed at the time of valve installation, so there are two clear options.

• Install signal cable from the valve position indicator to the control center.
• Install a wireless signal transmission system for the valve position indicator.

Unless the valve is located very close to the control center, the wireless option offers a more simple and cost effective method of connecting the valve position transmitter with the control center. Here are the basic tasks.

• Install transmitter at valve location in a suitable enclosure.
• Provide power to radio transmitter. Almost any power source can be accommodated. Power consumption is low enough to allow the use of a small solar panel and battery arrangement, if needed.
• Connect the valve position transmitter output to the radio transmitter input.
• Install a companion radio receiver at the control center, or where a wired signal can be routed easily to the control center. Provide a suitable enclosure.
• Provide power to the receiver, using any of the options available for the radio transmitter described previously.
• Connect the output of the radio receiver to an appropriate input on the central control system.
• Set the communications channels on the radio transmitter and receiver.
• Power up the system.

The transmitter digitizes and encrypts the input signal from the valve position indicator, then transmits the data via 900 MHz or 2.4 GHz to the receiver. The receiver decrypts the data and mirrors the signal that was delivered by the valve position indicator to the radio transmitter. 

This is a simplified illustration, but the implementation of a wireless connection between process components, even with all the details, is not difficult. Transmitters and receivers can be ordered pre-configured, wired, and installed in a specified enclosure, requiring comparatively little field labor. Analynk welcomes customized application challenges and your questions about how to utilize wireless connections in your operation. 

Analynk Wireless manufactures equipment used to establish wireless process connections across the room, across the plant site, across the highway, and around the globe.

Hazardous Area Enclosure for Aurba Access Point... and Others

AP623 Wireless access point enclosure
facilitates installation of commercial equipment
in hazardous industrial locations.

Analynk Wireless continues to expand its extensive line of wireless access point enclosures for hazardous industrial locations. The model AP623 is a recent addition, specially equipped to house the Aruba AP-314 dual band access point.

Analynk access point enclosures accommodate specific wireless access points from a range of manufacturers, facilitating easy installation. Every model includes UL listed explosion proof antennas, a mounting bracket custom tailored for the access point equipment, and RF cables to make the antenna connections. Enclosures have penetrations located to match up with 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.

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.

AP623 Hazardous Area Wireless Access Point Enclosure from Analynk Wireless, LLC

Product Options Match Wireless Equipment to Application

Analynk Wireless offers a broad range of accessories, options, and custom configuration and design services to complement their standard product offering of industrial wireless equipment. The specialty offerings can be used to extend the suitability of a standard product for a specific application, or to create a complete package with all necessary mounting brackets, antennas, cables, and other ancillary equipment needed for a complete installation. Analynk extends the same customizing capability throughout its Telmar line of process measurement and control products, as well.

The company welcomes all inquiries related to custom configuration, accessories, and turnkey system design. Share your wireless connectivity or process measurement and control challenges with the experts and Analynk, combining your process knowledge and experience with their design expertise to develop an effective solution.

Analynk Wireless Enclosure Options and More from Analynk Wireless, LLC

Rotary Vane Actuators for Quarter Turn Valve Automation

The inside of a rotary vane actuator
Image courtesy of Kinetrol

A rotary vane actuator is part of an automated valve assembly. Its role is to change the position of the valve trim, converting the motive force of fluid pressure in the actuator into torque at the valve stem.

Quarter turn valves are widely used in industrial fluid processes. Their application is primarily for operations requiring fully open or fully closed valve trim positions, although some do provide modulating service. A rotation of the valve stem through a 90 degree arc will reposition quarter turn valves between open and closed positions. A rotary vane actuator is well suited for driving this type of valve, with its own 90 degree arc of movement.

A rotary vane actuator is specific for application to quarter turn valves. A pressure tight housing contains a movable vane which is sealed to the sides of the pressure chamber by means of a low friction gasket. Inlets into the chamber on opposing sides of the vane allow a controller to produce a pressure differential across the vane. The vane will move, responding to the pressure differential, in either direction. A shaft is connected to the vane and the vane acts like a lever to rotate the shaft as the vane is moved by fluid pressure. The torque produced by the actuator assembly is primarily dependent upon the applied fluid pressure.

Hydraulic rotary vane actuators have the ability to handle large amounts of fluid and dynamic motions, exhibiting also qualities of durability and compactness. Pneumatic vane actuators use plant air pressure as the motive force. Both types generally have few moving parts and require little regular maintenance. A variety of typical automation accessories and options are available to customize a unit for a particular application.

Analynk Wireless manufactures wireless connectivity solutions for industrial applications and process control. Making cable free connections among process control equipment and instruments, across the room, across the property, across the globe.

Shell and Tube Heat Exchangers

View of the inside of a shell and tube heat exchanger shows
the tubes through which one of the transfer fluids passes.

Automobiles are part of the backbone of modern society, for both personal and commercial use. While being familiar everyday objects, they also contain systems which need to be constantly maintained and in-sequence to ensure the safety of both the machine and the driver. One of the most essential elements of car ownership is the understanding of how heat and temperature can impact a car’s operation. Likewise, regulating temperature in industrial operations, which is akin to controlling heat, is a key process control variable relating to both process operation and operator safety. Since temperature is a fundamental aspect of both industrial and consumer life, heat management must be accurate, consistent, and predictable. Many devices have been developed for the transfer of heat from one substance to another, with myriad applications throughout modern society.

A common design of heat exchangers used in the oil refining and chemical processing industries is the shell and tube heat exchanger. A pressure vessel, the shell, contains a bundle of tubes. One fluid flows within the tubes while another floods the shell and contacts the outer tube surface. Heat energy conducts through the tube wall from the warmer to the cooler substance, completing the transfer of heat between the two distinct substances. These fluids can either be liquids or gases. If a large heat transfer area is utilized, consisting of greater tube surface area, many tubes or circuits of tubes can be used concurrently in order to maximize the transfer of heat. There are many considerations to take into account in regards to the design of shell and tube heat exchangers, such as tube diameter, circuiting of the tubes, tube wall thickness, shell and tube operating pressure requirements, and more. In parallel fashion to a process control system, every decision made in reference to designing and practically applying the correct heat exchanger depends on the factors present in both the materials being regulated and the industrial purpose for which the exchanger is going to be used.

Schematic of shell and tube heat exchanger

The industrial and commercial applications of shell and tube heat exchangers are vast, ranging from small to very large capacities. They can serve as condensers, evaporators, heaters, or coolers. You will find them throughout almost every industry, and as a part of many large HVAC systems. Shell and tube heat exchangers, specifically, find applicability in many sub-industries related to food and beverage: brewery processes, juice, sauce, soup, syrup, oils, sugar, and others. Pure steam for WFI production is an application where special materials, like stainless steel, are employed for shell and tube units that transfer heat while maintaining isolation and purity of a highly controlled process fluid.

Shell and tube heat exchangers are rugged, efficient, and require little attention other than periodic inspection. Proper unit specification, selection, and installation contribute to longevity and solid performance.

Analynk Wireless manufactures wireless connectivity solutions for industrial applications and process control. Making cable free connections among process control equipment and instruments, across the room, across the property, across the globe.

Pyrometers

Pyrometers permit temperature measurement without contact

Non-contact measurement technology allows process operators and technicians to evaluate the temperature of process materials, machinery, or piping by measuring their electromagnetic radiation. Through inferential calculation and one or more radiation measurements, specialized instruments can determine temperature without contacting the subject material or surface. While the concept of non-contact measurement technology has existed for many years, more recent advancements in non-contact temperature sensing and the evolution of the pyrometer have allowed temperature measurement at a distance to become popular throughout industrial process operations.

Pyrometers can commonly concentrate light from an object onto a temperature sensing element. The sensed elevation in temperature is proportional to the infrared optical energy. Different instruments may have varying arrangements of concentrating lenses and sensors, but the operating principle is the same. The physical law behind the pyrometer’s operating principle operates on an exponential mathematical basis that is non-linear. This results in one of the limitations of the pyrometer. A single pyrometer can only, with high accuracy, deliver a comparatively narrow range of target temperature. If the need for accuracy is reduced, the applicable temperature range widens. Innovative manufacturers have developed instruments with technology and features overcoming many of the limitations imposed by the physics, delivering instruments with accuracy and applicable temperature range usable in a wide array of applications.

One of the advantages to using a non-contact pyrometer is that their calibration is independent of the distance between the sensor and the object being evaluated. This phenomenon is due to the fact pyrometers have a field of view and can be filled with the target object in a way independent of distance. While the radiation emanating from the target object may be decreasing, the field of view of the pyrometer is measuring a greater portion of the object which is proportional to the amount of radiation being lost, essentially canceling out the distance and allowing the pyrometer to provide useful output. An example of a practical application of a pyrometer in industry would be its use to check the temperature of a ventilation system in the HVAC field.

Share your temperature measurement requirements and challenges with process instrumentation specialists. Their product application expertise will combine with your own process knowledge and experience to produce an effective solution.

Analynk Wireless manufactures wireless connectivity solutions for industrial applications and process control. Making cable free connections among process control equipment and instruments, across the room, across the property, across the globe.

Hazardous Area Antennas Now Carry NEMA 4X Rating

The CTX and CTM antennas for industrial wireless
communications now carry a NEMA 4X rating

Analynk is well known in the industrial wireless communications field for its hazardous area antennas. Recently, certification was received as RoHS compliant. Analynk has now achieved a NEMA 4X rating for the CTM and CTX hazardous area explosion proof antennas, further expanding the range of applications and solidifying the product's reputation for high performance and ruggedness.

Data sheets for both the CTM and CTX series antennas are provided below, but sharing your industrial wireless communications challenges with the experts at Analynk Wireless is always the best path to an effective solution.

Industrial Wireless Communications - Hazardous Area Antennas from Analynk Wireless, LLC

Analynk Adds New Distributor in California

Analynk has added a new industrial distributor in California

Analynk Wireless manufactures a comprehensive line of wireless receivers, transmitters, and accessories that enable process operators to establish signal connections across the room, across the plant, and across the globe. The company recently added to their roster of authorized distributors to improve customer contact and support in California.

RealTech Controls, LLC is headquartered in Los Angeles and describes their company as follows:

RealTech Controls, LLC is a leading supplier of High Quality, Reliable Industrial Instrumentation and Control Equipment. 

Our products include: Wireless & Signal Conditioning Transmitters, Intrinsically Safe Devices, Water Treatment Analyzers / Controllers and Dosing Pumps, and Communication Converters.

We offer complimentary, professional advice and consultation, with over 20 years of Industry experience to specify and customize the correct product for your application.
Our industries of specialty are the Oil and Gas, Power, Water and Waste Water, Pharmaceutical, Food & Beverage, Cement and Process Automation.

Share your wireless connectivity challenges with industrial wireless experts. Combining your process knowledge with their expertise with produce effective solutions. Here, you can learn more about the Analynk product line.

Industrial Wireless as Mainstream Connection Method For Process Measurement

Establishing wireless connections for process control operations
is simple, effective, and inexpensive

Wireless connections to process instrumentation has evolved to a point where it is uncomplicated and inexpensive. Many facilities rely on wireless connections, either via a network (wifi) or point to point communications. The benefits of wireless are well known to those already among users of the technology.

• Safety: Wireless connections can reduce personnel exposure to hazardous environments or situations that previously required human intervention or a manual gauge or instrument reading.
• Easy Scale-up: Adding points on a network is generally a simple incremental process.
• Operational Advantage: When deployed to replace manual instrument or gauge readings, real time data for diagnostics and efficiency measurements are now available. Information that is more accurate, timely, and consistent will produce better results.
• Installation Savings: Installation of wireless connected assets has been reported to be up to 10 times less expensive than wired installation. The reduced space and planning for cables and conduit can make what were once complex and time consuming operations much quicker and easier.
• Mobility: Wireless technology allows for real time connections to mobile platforms. Whether within a plant, on the road, or on the high seas, there are wireless products that can make the connection.
• Distance: Don't just think WiFi, think radio, think satellite, think cellular. Connections can be established across very long distances using standard products from the industry.
• Conversion of Legacy Devices: Many existing in-place devices can have their wired connections replaced with a wireless version. This accommodates a staged transition from wired to wireless in facility.

The transmission is accomplished in either the 900 MHz or 2.4 GHz band, delivering adequate range and power for most facility-wide applications. Obstructions can be overcome with the use of a strategically located repeater. Properly planned and configured, there are few limits to the distance a wireless connection can span.

Point to point wireless connections between, for example, a temperature transmitter and a recorder are easy to create. Most process sensors have very small power requirements, as do the Analynk transmission units. Power, if line voltage is not available at the location, can be provided by batteries, or combination of battery and photovoltaic. The 4-20 mA signal from the temperature transmitter serves as the input signal to the wireless transmitter. The analog signal is converted to a digital value and encrypted prior to transmission. A receiver at the recorder decrypts the digital signal and converts it back to a 4-20 mA analog output that serves as the input signal to the recorder. Wireless transmitter and receiver must be set to the same channel, but otherwise, the equipment handles all the work. If you can find your way around a smart phone, you can make a wireless point to point process connection.

There are likely many applications going unfulfilled because the cost or feasibility of making a wired connection is holding the project back. Reconsider the project using industrial wireless technology and you may find that the project becomes an attractive prospect.

Analynk Wireless designs and manufactures wireless communication equipment and systems for use in commercial and industrial settings. Share your connectivity challenges with the experts at Analynk, combining your own process knowledge and experience with their wireless communications expertise to develop an effective solution.

Water Quality Analysis – Constituent Survey Part 3

Water quality is of great concern to electric power generating
operations, as well as other industrial operations

What we know as “water” can consist of many non-H2O components in addition to pure water. This three part series has touched on some of the constituents of water that are of interest to various industrial processors. The first installment reviewed dissolved oxygen and chloride. The second article covered sulfates, sodium, and ammonia. 

To conclude the three part series on water quality analysis in process control related industrial applications we examine silica, another element which in sufficient quantities can become a confounding variable in water for industrial use. In natural settings, silica, or silicon dioxide, is a plentiful compound. Its presence in water provides a basis for some corrosion-inhibiting products, as well as conditioners and detergents. Problems arise, however, when high concentrates of silica complicate industrial processes which are not designed to accommodate elevated levels. Specifically, silica is capable of disrupting processes related to boilers and turbines. In environments involving high temperature, elevated pressure, or both, silica can form crystalline deposits on machinery surfaces. This inhibits the operation of turbines and also interferes with heat transfer. These deposits can result in many complications, ranging through process disruption, decreased efficiency, and resources being expended for repairs.

The silica content in water used in potentially affected processes needs to be sufficiently low in order to maintain rated function and performance. Silica analyzers provide continuous measurement and monitoring of silica levels. The analyzers detect and allow mitigation of silica in the initial stages of raw material acquisition or introduction to prevent undue disruption of the process. Additionally, a technique called power steam quality monitoring allows for the aforementioned turbine-specific inhibition – related to silica conglomerates reducing efficacy and physical movement – to be curtailed without much issue. The feedwater filtration couples with a low maintenance requirement, resulting in reduced downtime of analytic sequences and a bit of increased peace of mind for the technical operator.

While silica and the other compounds mentioned in this series are naturally occurring, the support systems in place to expertly control the quality of water is the most basic requirement for harvesting one of the earth’s most precious resources for use. As a matter of fact, the identification and control of compounds in water – both entering the industrial process and exiting the industrial process – demonstrates key tenets of process control fundamentals: precision, accuracy, durability, and technological excellence paired with ingenuity to create the best outcome not just one time, but each time.

Analynk Wireless manufactures wireless connectivity solutions for industrial applications and process control. Making cable free connections among process control equipment and instruments, across the room, across the property, across the globe.

Water Quality Analysis – Constituent Survey (Part 2)

Water is a big part of countless industrial operations, either as
an input, part of processing, or a waste product.

It would be difficult to understate the role and importance of water in industrial processing, even our own biological existence. In the first installment of this series, the roles of dissolved oxygen and chlorides were covered.

Continuing the examination of water quality monitoring in municipal and industrial processes, another key variable which requires monitoring for industrial water use is sulfate. Sulfate is a combination of sulfur and oxygen, salts of sulfuric acid. Similarly to chlorides, they can impact water utilization processes due to their capability for corrosion. The power generation industry is particularly attuned to the role of sulfates in their steam cycle, as should be any boiler operator. Minerals can concentrate in steam drums and accelerate corrosion. Thanks to advancements in monitoring technology, instruments are available which monitor for both chlorides (covered in the previous installment in this series) and sulfates with minimal supervision needed by the operator, ensuring accurate detection of constituent levels outside of an acceptable range. Ionic separation technologies precisely appraise the amount of sulfate ions in the stream, allowing for continuous evaluation and for corrective action to be taken early-on, avoiding expensive repairs and downtime. 

Another substance worthy of measurement and monitoring in process water is sodium. Pure water production equipment, specifically cation exchange units, can be performance monitored with an online sodium analyzer. Output from the cation bed containing sodium, an indication of deteriorating performance, can be diverted and the bed regenerated. Steam production and power generation operations also benefit from sodium monitoring in an effort to combat corrosion in turbines, steam tubes, and other components. Sodium analyzers are very sensitive, able to detect trace levels. 

Ammonia is comprised of nitrogen and hydrogen and, while colorless, carries a distinct odor. Industries such as agriculture utilize ammonia for fertilizing purposes, and many other specializations, including food processing, chemical synthesis, and metal finishing, utilize ammonia for their procedural and product-oriented needs. An essential understanding of ammonia, however, includes the fact that the chemical is deadly to many forms of aquatic life. Removing ammonia from industrial wastewater is a processing burden of many industries due to the environmental toxicity. 

Methods for removing ammonia from wastewater include a biological treatment method called ‘conventional activated sludge’, aeration, sequencing batch reactor, and ion exchange. Several methods exist for in-line or sample based measurement of ammonia concentration in water. Each has particular procedures, dependencies, and limitations which must be considered for each application in order to put the most useful measurement method into operation. 

As water is an essential part of almost every facet of human endeavor and the environment in which we all dwell, the study and application of related analytics is an important component of many water based processes. The variety of compounds which can be considered contaminants or harmful elements when dissolved or contained in water presents multiple challenges for engineers and process operators.

Analynk Wireless manufactures wireless connectivity solutions for industrial applications and process control. Making cable free connections among process control equipment and instruments, across the room, across the property, across the globe.

Water Quality - Constituents That Impact Industrial Operations (Part 1)

Sewage treatment plants are only one of many applications
where water quality is a concern.

Of all the raw materials available for human consumption – aside from the air we breathe – the most vital component of life on earth is water. In addition to the global need for humans to drink water in order to survive, the use of water is essential in a myriad of industries relating to process control. Whether the goal is the production or monitoring of pure water for industrial use, or the processing of wastewater, the ability to measure the presence and level of certain chemical constituents of water is necessary for success.

In order to use water properly, industrial professionals combine state of the art analyzers with technical expertise to evaluate water quality for use or disposal. Two essential values of process control are ensuring elements of a control system are accurate and secure, and, furthermore, that they are accurate and secure for each product every time. By properly vetting water in industry, engineers and other personnel in fields such as pharmaceuticals, chemical, food & beverage, brewing, power, and microelectronics are able to maintain standards of production excellence and conform with regulatory requirements related to water quality.

The amount of dissolved oxygen present in water can correlate with the degree of movement at an air-water interface, also being impacted by pressure, temperature, and salinity. Excessive or deficient dissolved oxygen levels in industrial process waters may have an impact on process performance or end product quality. Likely, the most common application for dissolved oxygen measurement is in the evaluation of wastewater for biological oxygen demand. The primary function of dissolved oxygen in wastewater is to enable and enhance the oxidation of organic material by aerobic bacteria, a necessary step in treatment.

To measure dissolved oxygen, specialized sensors and companion instruments are employed that require careful maintenance and trained technical operators. The level of measurement precision varies depending on the industry employing the technology, with numerous applications also being found in the food & beverage and pharmaceutical industries. In-line continuous measurement is used in wastewater processing to determine if the dissolved oxygen remains in a range that supports the bacteria necessary for biodegradation.

Chloride concentration in wastewater is strictly regulated. Industrial and commercial operation effluent can be regulated with respect to allowable chloride content. While commonly found in both streams and wastewater, chlorides, in large amounts, can present challenges to water utilization or processing facilities. Chloride levels impact corrosion, conductivity, and taste (for industries in which such a variable is paramount). In a process system, having an essential component marred due to elevated quantities of a substance could reverberate into any end-product being manufactured. Chloride analyzers, some of which can also detect and monitor other water characteristics, serve as important tools for water consuming facilities to meet regulatory standards for effluent discharge or internal quality standards for recycling.

There are other constituents of what we refer to as “water” that are subject to measurement and monitoring for a range of institutional, industrial, and municipal applications. Those will be explored in the next part of this article series.

Analynk Wireless manufactures wireless connectivity solutions for industrial applications and process control. Making cable free connections among process control equipment and instruments, across the room, across the property, across the globe.

Continuous Liquid Level Measurement Technologies Used in Industry

Process measurement connectivity with wireless technology
is suitable for almost any application 

Although continuous level measurement technologies have the ability to quantify applications for bulk solids, slurries, and granular materials, this article will focus on level measurement technologies applied to liquid level measurement utilized in process control. A distinction should be made between continuous level measurement and point level measurement. Point level measurement acts like a switch, changing state when a single level condition is achieved. Called “transmitters,” continuous liquid level measurement devices employ technologies ranging from hydrostatics to magnetostriction, providing uninterrupted signals that indicate the level of liquid in a vessel, tank, or other container.

Hydrostatic devices focus on the equilibrium of dynamic and static liquids. There are three main types of hydrostatic transmitters: 1) displacer, 2) bubbler, and 3) differential pressure.

The displacer transmitters utilize a float placed within the liquid container. With its buoyancy characterized to the liquid and the application, the float, a connecting stem, and a range spring or similar counterbalance represents the liquid level in terms of the movement of the displacer (float). The displacement, or movement, of the assembly is converted into an electric signal for use by the monitoring and control system.

Bubbler transmitters are used for processing vessels that operate at atmospheric pressure. This method introduces a purge gas or an inert gas, e.g. air or dry nitrogen, into a tube extending into the liquid vessel. Precise measurement of the pressure exerted on the gas in the dip tube by the liquid in the tank is used to determine the height of the liquid.

Differential pressure (DP) transmitters rely directly on, in a basic explanation, the pressure difference between the bottom and top of the container. Precise pressure measurement is used to determine the height of the liquid in the tank. One of the most advantageous aspects of DP transmitters is that they can be used in pressurized containers.

Other examples of level transmitter technologies which are not hydrostatic devices include magnetostrictive, capacitance, ultrasonic, laser, and radar.

In magnetostrictive level transmitters the measuring device, a float, has a magnet that creates a magnetic field around a wire enclosed in a tube. Electrical pulses sent down the wire by the transmitter head produce a torsional wave related to the position of the float, which moves with changes in liquid surface level. The transit time of the torsion wave back to the sensing head is measured and the depth of the liquid, as indicated by the float position, can be determined.

Capacitance transmitters are best applied to liquids that have high dielectric constants. Essentially, changes in the capacitance of the sensor / tank / liquid assembly will vary proportionately with the liquid level. The change in capacitance is measured and converted to an appropriate electrical signal.

Ultrasonic level transmitters emit ultrasonic energy from the top of the vessel toward the liquid. The emissions are reflected by the liquid surface and them time required for the signal to return to the source is used to determine the distance to the liquid surface.

Laser level transmitters operate similarly to an ultrasonic level transmitter. However, instead of using ultrasound signals, they use pulses of light.

Radar level transmitters involve microwaves emitting downward from the top of the container to the liquid’s surface. The measured time for receipt of a return sign reflecting off the liquid surface enables calculation of the distance from the sensor to the liquid surface.

The precise measurement of transmit time for a wave or pulse of energy is employed in several of the technologies, the measurement of pressure in others. Each technology has a set of attributes making it an advantageous selection for a particular range of applications.

Analynk Wireless provides connectivity solutions enabling the wireless transmission of measurement data across the room, across the property, across the globe. Share your process measurement and control connectivity challenges with the experts at Analynk for a solution that is simple to implement and cost effective.

Wireless Communications Deliver Real Time Process Data From Remote Operating Sites

No distance is too near or far for industrial wireless
communications

Oil is where you find it, with many prospecting and production sites located where the communication options taken for granted in developed areas do not exist. Oil is big and serious business, with tremendous sums of money at risk on the prospect of reaping even greater returns. Every business operation, though, is of great importance to the stakeholders. Countless operations in little known industries and endeavors are located beyond the boundaries of modern communications infrastructure. 

If you want a data connection, bring your own.

Remote operating sites, whether for oil extraction or other purposes, will often be automated. Some decision making system or individual is responsible for the safe and effective operation of the remote site, or has a use or need for real time data being gathered at the remote site. Radio transmission is a viable, maybe the best, option for delivering real time data from a remote site to a central office.

• Transmission options for 900 MHz, 2.4 GHz, cellular, and satellite systems are readily available.
• Equipment operates on low voltage, low power. Suitable for solar or other remote site power source.
• No special instrumentation needed. Radio transmitting and receiving equipment interfaces directly with analog signals from common industrial process transmitters.
• No "across the land" cabling needed.
• Equipment can be configured to resist extreme environmental conditions.

Analynk manufactures transmission and receiving equipment that builds the bridge between remote sites and the home office. From elemental componentry to integrated, ready to run systems, Analynk specializes in wireless communications for industrial process control. Contact us with your wireless challenges. Whether an expansive multipoint, or a single point application, the specialists at Analynk can combine standard or customized products into a practical solution for every application.

One Transmitter, One Receiver, Multiple Process Signals

A16000 Multiple I/O Module
Analynk

Radio frequency (RF) communications can enable the establishment or cost effective, quick, process signal connections across very small or very large distances. A misconception arises, from time to time, that it is necessary to have a dedicated transmitter and receiver for each process signal. Analynk has a solution that provides for delivery of up to sixteen process signals over a single transmission path.

Wireless transmission of process control signals is steadily increasing in prevalence throughout commercial, institutional and industrial settings. The ease of implementation, with no long cable runs to plan, layout, install, protect, and maintain, allows wireless installations to fulfill application niches that may have been considered impractical in the past.

Analynk provides hardware that easily allows the transmission and reception of up to 16 I/O points using a single transmitter and receiver. The A16000 Expansion Module can be configured with up to four internal cards that accommodate various types of input and output signals. The process is similar to setting up the I/O on a PLC. Connect the process signals to the A16000, and the A16000 to one of Analynk's transmitter or receiver devices. Setup is straight forward and allows the installation to be operable in minimal time.

Share your wireless communications and signal transmission challenges with the experts at Analynk and get recommendations on how to best implement workable solutions.

Analynk Model A16000 RF Expansion Module from Analynk Wireless, LLC

Automation and Grain Processing

Grain processing benefits from automation and industrial wireless

The grain industry serves as an example of industrial process control, where standards are maintained at a constant rate for product delivery. Automation in grain processing provides both safety and efficiency by supporting the product delivery process. Historically, the grain production process has been hazardous, with industry workers subject to harsh conditions and potential risks associated with the grain, such as flammable grain dust. The transition from manual labor to automation has become the industry’s essential shift, with automation now a staple in harvesting, milling, and handling grain. The developers of automation components seek to mitigate production ineffectiveness and inventory miscalculations. Solids level transmitters, responsible for continuously monitoring the amount of grain in potentially hazardous environments, are a reliable replacement for employees at a silo’s peak.

Thanks to developments in technology, the implementation of sustainable automation does not need to come at the expense of company profit. A sole driver needs to control automation operations when dealing with grain handling, meaning that the number of employees put at risk via that stage in the process is substantially reduced. In order to keep track of inventory, automated management tracks not only the levels of grain inside silos but also where materials are located throughout the production facility. Grain sensors allow for the constant communication of how much grain is being moved through grain elevators and terminals. Instrumentation measures level, weight, and flow of solid grain while maintaining process protection.

Grain terminals allow for grain to be unloaded into hoppers, and then conveyors transfer those hoppers to the elevators. Cleaning drying, and blending machinery all employ automation, reducing the risks presented to employees. Truck and rail load-outs need to be close to target levels, because overloading or under-loading transport results in product loss. Preventing the loss of time and physical resources is a key element of automation. Radar transmitters cut through dust in silos to deliver reliable information back to the process operators. Ultrasonic instrumentation matches with point level technology to indicate when grain levels are high or low.

The handling and blending of raw materials can be monitored by solid flowmeters, with high accuracy still applicable in more compact spaces. A similar solid flowmeter ensures the accuracy of the flow rate and weight of solids measured in bulk, and can also be used in tandem with flow and weigh feeders to keep each individual load of grain consistently accurate. The applications of automation throughout the grain production process have evolved into a reliable means of reducing employee risk while ensuring accuracy and increasing throughput.

Grain operations cover large areas. A reliable, flexible, and cost saving way to establish the needed process control connections throughout the facility is via industrial wireless. Connections between measurement instruments and control units can be created across very long distances without the need to install conduit and cabling. Connections can be created quickly and reliably, with flexibility to increase throughput as more stations or sensors are needed. Equipment is suitable for general or hazardous locations. Contact an industrial wireless communications expert for help in developing connections on your project.

Diaphragm Seals Protect Industrial Pressure Gauges and Transmitters

Industrial pressure gauge with diaphragm seal installed
Courtesy Wika

Pressure measurement is a common element of industrial operations and control systems. Fluid processing can often involve media that is potentially harmful to pressure sensing devices. The media may be corrosive to the sensor material, or other media properties may impact the performance or usable life of the instrument. In process control environments, diaphragm seals play a role in protecting items like pressure sensors from damage by process fluids. The diaphragm seal is a flexible membrane that seals across the connecting path to a sensor and isolates the sensor from the process media. System pressure crosses the barrier without inhibition, enabling accurate measurement, but the process fluid does not. Typical materials composing diaphragm seals are elastomers, with a wide variety of specific materials available to accommodate almost every application.

In the operating principle of the diaphragm seal, the sealed chamber created between the diaphragm and the instrument is filled with an appropriate fluid, allowing for the transfer of pressure from the process media to the protected sensor. The seals are attached to the process by threaded, open flange, sanitary, or other connections. Diaphragm seals are sometimes referred to as chemical seals or gauge guards. Stainless steel, Hastelloy, Monel, Inconel, and titanium are used in high pressure environments, and some materials are known to work better when paired with certain chemicals.

Sanitary processes, such as food, beverage, and pharmaceuticals, use diaphragm seals to prevent the accumulation of process fluid in pressure ports, a possible source of contamination. If such a buildup were to occur, such as milk invading and lodging in a port on a pressure gauge, the resulting contamination compromises the quality and purity of successive batches. Extremely pure process fluids, like ultra-pure water, could be contaminated by the metal surface of a process sensor. Some pneumatic systems rely on the elimination of even the smallest pressure fluctuations, and diaphragm seals prevent those by ensuring the separation of the process materials from the sensors.

Diaphragm seals are not without some application concerns, and devices are now built to address and counter many potential issues related to the use of diaphragm seals with process monitoring instruments and equipment. Products seek to eliminate any and all dead space, allow for continuous process flow, and are self-cleaning thanks to continuous flow design. Some high pressure seals come equipped with anti-clogging features, accomplished by the elimination of internal cavities while protecting gauges. Multi-purpose seals reduce temperature influence and improve instrument performance while pinpointing and diffusing areas of high stress. These pre-emptive measures result in longer instrument life-cycles and improved performance while ensuring protection from corrosion.

There are numerous options and available diaphragm seal variants. Share your application specifics with a product specialist, combining your own process knowledge and experience with their product application expertise to develop an effective solution. Analynk Wireless manufactures industrial wireless communications equipment and process transmitters.