Specialty Enclosures Complete Instrument and Equipment Installations

Analyzer Cabinet
Courtesy Intertec

Industrial environments present a wide range of challenges to the process designer or operator looking to install sensitive instrumentation or controls. Not all devices come with integrated enclosures suitable for all environments. The responsibility for properly housing equipment, controllers, and other instruments can fall on the process designer or operator.

There are numerous considerations in the design and selection of an enclosure, especially when the application drifts beyond the range of commonly available sizes, configurations, and materials of construction. Here are some thinking points for you.

Instrumentation safely housed
while clearly visible to operator
Courtesy Intertec

• Ignition Hazard Level: Areas or locations with hazardous classifications will require special enclosure designs and features for compliance.
• Climate: If outdoors, consider the range of local weather conditions and their potential impact on the longevity and performance of the enclosure, its ability to protect whatever is housed within.
• Access: Do operators need quick access to contained equipment? If so, appropriate latches or other closures that allow interior access without a need for tools may be in order. Security concerns may warrant locking capability. A clear panel installed in a door can provide visual access to instruments safely contained within the enclosure.
• Corrosion: Wet environments or locations near seawater or other corrosive elements can call for upgraded coatings or materials of construction that will prolong the useful life of the enclosure.
• Enclosure Cooling or Heating: Depending upon the surrounding temperature or the characteristics of equipment housed in the enclosure, heat removal or supplementing accessories may be integrated into the enclosure design.
• Size: Consideration given to possible additions to the original array of instruments or devices to be contained can save substantial time and money if a future expansion is in order. The size of the enclosure should provide for any clearance  recommended by device  manufacturers for their installed components. Provide adequate servicing space for field technicians to perform any necessary tasks related to housed equipment.
• Penetrations: Conduit or other penetrations required for proper operation and installation can be accomplished more precisely, and often at a lower cost, in the factory than in the field. Carefully laying out and coordinating the installation of connections to the enclosure can save time and trouble in the field.

Certainly, there are numerous other elements of enclosure design that may be taken into account for differing installation requirements. Share your project requirements with application specialists and reach the best solutions by combining your process knowledge with their product expertise.

Simplifying Plant Safety Instrumentation

Series One Safety Transmitter and Switch
Courtesy United Electric

Safety implementation typically is accomplished by a group that includes plant instrument engineers and technicians. They are charged with developing simple and reliable solutions that increase safety and reduce risk. Safety related events can involve the question of when to shut a process down. These decisions can hinge on the level of key process variables such as flow, level, temperature and pressure. All must be within their specified range at various locations throughout the process, whether within chemical and petrochemical plants, refineries and power plants, or other processing operations. Critical points of measurement can include anything from process vessels to eye wash stations.

For such point safety applications, a properly designed and implemented digital switch with self-diagnostics can be an important part of the answer. As an element of a multiple technology solution, a digital switch-based approach can help eliminate common-mode failures, significantly improve response time, achieve needed safety integrity levels (SILs), and simplify plant safety instrumentation.

United Electric Controls has authored a white paper entitled "Simplifying Plant Safety Instrumentation" that provides some insight into deployment of safety controls. The entire white paper is included below and will prove to be useful reading. More detailed product and application information is available from product specialists. Combining their product expertise with your process knowledge will produce the best solutions.

Simplifying Plant Safety Instrumentation from Miller Energy, Inc.

"Bubbler Method" Liquid Level Measurement

An accurate pressure transmitter
is an integral part of  a liquid level
measurement system using the
"Bubbler Method"
Courtesy Brooks Instrument

Measuring liquid level in a tank or vessel can be accomplished in a number of ways, all of which require some arrangement of instrumentation to either infer the liquid level from the measurement of a related physical property, or directly deliver the liquid level visually using a scaled gauge arrangement. One indirect method of level measurement is often referred to as the bubbler method, so named because it employs a purging gas that continually vents from the bottom of a tube extending into a tank of liquid. Through a simple apparatus, the level of a liquid can be inferred by the amount a back pressure exerted upon the gas flowing through the tube.

Probably the greatest advantage of this method of liquid level measurement is that the liquid does not contact the sensing instrumentation. The only portion of the apparatus in contact with the liquid is a tube immersed into the tank. Basically, a purge gas flows through the immersion tube and may bubble out the immersed end of the tube, which is open to allow the contained liquid to exert a hydrostatic pressure on the purge gas. The back pressure on the gas that is exerted by the liquid contained within the tank will vary directly with the depth of the liquid. The back pressure can be correlated to a liquid level. Further calculations, which would include the tank shape, dimensions, and the liquid density can provide an indication of the volume and mass of the liquid. Here is an illustration of the setup, provided courtesy of Brooks Instrument, globally recognized leader in flow and pressure measurement and control. The illustration is from Brooks' January blog article.

Bubbler Method Tank Level Measurement Apparatus, showing application of some Brooks Instrument devices.

Below are data sheets detailing the components used in the system to control and measure the gas flow, and measure the back pressure on the immersion tube. There are other components needed for a complete system, but they are fairly generic in nature and easily obtainable. Contact a flow and level measurement specialist with your application challenges and work with them to produce effective solutions.

Bubbler Method Liquid Tank Level Measurement Instruments from Miller Energy, Inc.

Low Cost Radar Level Transmitter For Industrial Process Applications

Magnetrol Model R82 Radar Level Transmitter

With its ability to reliably detect tank liquid surface level under conditions that prove challenging to other methods, radar technology generally provides an operational advantage over other non-contact level measurement options. Historically, the cost of radar level transmitters for industrial process control applications has hindered their success as a unit of choice for some installations. Magnetrol has changed that imbalance with their recent introduction of a lower cost radar level transmitter for tough applications.

The Model R82 provides radar performance at a price point comparable to competitive ultrasonic units, but maintains the performance advantage inherent in a radar based device. The unit utilizes pulse burst radar technology at 26 GHz, employing advanced signal processing to filter out false echos produced by a range of in-tank conditions that can produce false readings from ultrasonic units.

The short video below provides a closer look at the R82 and its performance advantages. Technical data sheets and any application assistance you may need is available from product specialists. Share your level measurement and control challenges with them and work toward the best solution.

Yokogawa Users Conference and Exhibition is Coming

Yokogawa is presenting its 2016 Users Conference and Exhibition in Orlando, Florida. The event runs from October 3 through October 6 and will be held at the Renaissance Orlando at SeaWorld hotel. Included in the conference agenda are informative technical sessions, training workshops, panel discussions, hands-on demonstrations, essential application sessions, and daily keynote speakers. The opportunities for networking and learning are truly unique and rewarding for those involved in process automation and control.

There is currently a call for presentations, seeking out those who wish to share their applications and challenges. Learn more about the conference and register at the event website.

Yokogawa Users Conference and Exhibition from Miller Energy, Inc.

Yokogawa Publishes New Collection of Case Studies in Process Automation and Control

Yokogawa, an internationally recognized process automation and control provider, strives for customer satisfaction through operational excellence, bringing long-term success to its customers. Now available are collections of actual cases in which Yokogawa helped leading companies in a variety of industries address specific challenges and achieve their goals. The new e-books were redesigned and subdivided into six sectors including LNG, Oil & Gas, Chemical, Pharmaceutical, and Renewable Energy.

Browse the e-books online for insight into the breadth and depth of Yokogawa's capabilities and their commitment to their customer's success. Depending on your screen size, you may need to scroll down the page to see the e-books at the link. At e-books, you can browse using the online reader, or download them as a PDF file.

Share you process control challenges with a Yokogawa representative and expect the best solutions.

Save Time And Get The Right Product With Yokogawa Automated Selection Tool

Yokogawa Corporation of America, an industry recognized source for innovative process measurement and control products, has made available an easy to use product selection tool for those navigating through the company's extensive product offering. The Product Finder is a great time saver that enables a user to quickly locate product and technical information on Yokogawa process instrumentation products meeting the user's selected criteria.

Let's step through a quick example. You will see how this quick and easy to use tool saves time by navigating quickly to the website pages detailing products meeting your requirements.

The Product Finder is accessible through a number of links throughout Yokogawa's network of representatives. Clicking the link lands you on the start page of the Product Finder. For this example, I am going to search for a flow meter with the following characteristics:

• Mass flow measurement 
• Non-conductive liquid
• Accuracy of 1%
• Flow measurement device must have an integral transmitter
• Tri-clamp connections

Above, I declared my location as United States. The next step, shown below, is to select "Flow" as the measurement parameter. You will see in the drop down menu that there are many measurement elements that can be selected, with Yokogawa products for each.

My selection of "Flow" from the drop down menu returns all of the company's flow measurement devices, of which there are many (this cropped screenshot, shown below, only shows four, but there were many more) . This is where the selector really helps you. Instead of examining several or many different models, the user can focus the search by adding more product characteristics. You can see the list of prompting questions on the left side of the page. Providing additional characteristics by answering the prompting questions will narrow the search results to the show only the products meeting all the criteria specified by the user.

The next image (below) shows all of my sample product attributes entered on the left column. Note that there is now only a single product that matches all of my sample criteria. The whole process took less than two minutes. By clicking on the "View More Details" button below the product image, I gain access to all of the available technical, support, and product data for my selected flow measurement device.

The process instrumentation specialists at Miller Energy are available to provide additional help in meeting your measurement challenges. Combine their product knowledge and expertise with your process know-how for the best solutions.

Vortex Flowmeter Delivers High Performance in Harsh Process Conditions

digitalYEWFLO Vortex Flowmeter
Courtesy Yokogawa

In the process measurement and control field, vortex flowmeters are noted for their ruggedness, versatility, comparatively high accuracy, and absence of moving parts. They are compatible with numerous applications requiring measurement of flow in gases, liquids, and steam. The Yokogawa digitalYEWFLO vortex flowmeter is an accurate and stable device, even in harsh process conditions, and has a highly reliable and robust design that can deliver improvements in plant efficiency and reduced operating costs. It is available in several versions, one of which is multivariable, providing a calculated mass flow rate output.

Operating Principle

When a shedder bar is placed in a flow, Karman vortices are generated on the downstream side of the bar. The Karman vortices are detected by two piezoelectric elements installed in the upper part of the shedder bar. The vortex frequency is proportional to the flow velocity in a specific range of Reynolds numbers. Therefore, flow velocity or flow rate can be determined by measuring vortex frequency.

Noise Reduction

Noise caused by strong piping vibration may affect the accuracy of vortex frequency detection. The two piezoelectric elements in the digital YEWFLO are installed in a configuration that is polarized, so they are not affected by vibration in the flow or vertical directions. The noise of vortex (lift)- direction vibration is reduced by adjusting the outputs of the piezoelectric elements. Combining these features with the Spectral Signal Processing (SSP) function provides optimum and stable measurement.

Share your process measurement challenges with a product application specialist. The sharing of ideas and information will produce the best outcome.

Yokogawa digital YEWFLOW Vortex Flowmeters from Miller Energy, Inc.

Handheld HART Communicator Boosts Field Technician Productivity

Yokogawa YHC5150X

The Yokogawa FieldMate family effectively supports the initial setup, daily maintenance, and troubleshooting for the maximum utilization of intelligent field instruments. FieldMate is a flag ship product of the FieldMate family which is a PC based full functional and full field protocol configuration tool. 

The YHC5150X FieldMate Handheld Communicator is the latest HART® Communicator from Yokogawa. All HART® field devices can be configured, polled, and trimmed utilizing a Windows Embedded CE™ based system for faster processing and greater storage capacity. All options are standard and no subscription is required. The YHC5150X is a full function, DD Direct, HART® Communicator supporting universal, common practice, and device specific commands for commissioning, configuration, and maintenance operations. 

A short listing of some of the more prominent features that make the YHC5150X a powerful universal HART communicator include...

• Reads manufacturers' DDs in their native format without the need for translations 
• HART®-compliant modem communicates with any registered or unregistered HART® Device 
• Features an ergonomic, handheld design 
• Enhanced 4.3" diagonal anti-glare touchscreen with color graphic display (no stylus required) 
• Full QWERTY keyboard for commissioning new transmitters 
• On-Demand Help Menus and teachable device-specific short cuts 
• More than twice the battery capacity of any handheld communicator 
• Manage device information through PC connection 
• Integrated multi-language support

The video below provides additional detail and an overview of the product in action. More information on the HART Communicator, as well as other innovative products to improve productivity and effectiveness, is available from a product specialist.

Optimizing Level Control in Combined Cycle Gas Turbine Plants

Magnetrol® International and Orion Instruments®, both recognized global innovators in level measurement technology, provide optimizing solutions for liquid level control in combined cycle gas turbine plants and other similar applications.

An overall cost analysis can reveal savings in the range of 25% to 35% through the application of the most advantageous level measurement technology. Miller Energy, Inc. has developed a short presentation and discussion regarding recent developments now available in the Magnetrol® Eclipse Line of guided wave radar level instruments.

More detail is provided on the single page document provided below. Reach out to Miller Energy and learn how your operation may benefit from the application of guided wave radar level measurement technology.

Optimizing Level Control - Combined Cycle Gas Turbines from Miller Energy, Inc.

Develop a Thoughtful and Comprehensive Alarm Plan for Process Control Operations

Petrochemical plants are one of many industrial process
control operations to benefit from comprehensive alarm plans

Industrial process control operators and designers have the capability to measure many aspects of machine operation and process performance. Determining the elements to measure, method of measurement, and how to handle and process the derived information can be challenging, but can also impact the security, performance, and safety of an operation. A plan for monitoring, reporting, and responding to abnormal process conditions, if properly developed and executed, can yield real benefits to a process operator. A protocol that is not well conceived may produce a negative operational impact by creating events that unnecessarily draw resources away from productive endeavor. That protocol, or plan, is often referred to as an alarm plan.

There are numerous forces that can influence the development and implementation of an alarm plan. Each operation must incorporate its own set of external regulatory requirements, internal procedures and policies into a complete alarm protocol. Distilling that macro description down to a workable set of procedures and response tasks is where the real work begins. There is, however, a basic framework that can help organize your thinking and focus on what is most important.

• What parameters define the process or operation?
  Produce a schedule of every non-human element that is required to make the process function. This will require drilling down through every machine and material that is part of the operation. Expect the schedule to be extensive, even huge. If it is not, consider that your analysis may not be reaching deep enough. The goal here is to create an overview of what makes the process work and provide a tool for systematically studying the process elements and gleaning possible commonalities or relationships among them. Consider disregarding things that cannot be measured, since that prevents the derivation of data for evaluation. Review the completed schedule and decide which parameters shall be measured and evaluated for proper performance.
• What level of measurement is needed for each monitored parameter?
  An assessment of the needed accuracy, frequency, and resolution for parameter measurement will help define the requirements for instrumentation or other devices used to monitor a particular item. The goal is to make sure the monitoring device is capable of detecting and delivering information of sufficient quality to make decisions.
• Define the limits of acceptability for each monitored parameter.
  Until the endpoint of the process or operation, each step is likely dependent in some way on previous steps. The output of each step becomes the input of the next. While this, in many cases, may be an oversimplification, it is important to consider the relationships between the tasks and operations that comprise the process. Monitored parameters should relate to the successful completion of a process step, though not necessarily be a direct indicator of success. The maintenance of the parameter within certain bounds may be used as an indicator that a component of successful completion was properly attained. Defining limits of acceptability may involve an element of subjectivity and will likely be customized to accommodate the process. Each organization shall evaluate their operation and determine limits based upon intimate process knowledge and experience.
• Define abnormal operation for each monitored parameter.
  Abnormal operation may not necessarily be any value not within what is considered acceptable. Consider abnormal to be the range of values that would be cause for notification of the operator, or even automated or human intervention. Note that the definition of unacceptable or abnormal operation might appropriately include filters or defined relationships with other parameters. An example of a simple filter is a time delay. If the measured variable exceeds the specified limit for 2 seconds, it make not be significant. If the threshold is exceeded for 2 minutes, it may be cause to take action. As with the limits of acceptability, developing the definition of abnormal operation for each parameter will be customized for each process.
• Provide a defined response for every alarm occurrence.
  If it is important to monitor something, then it is likely important to do something when things get out of hand. Human executed alarm response should be concise and uncomplicated, to reduce the probability of error. Automated response should be designed in a manner that provides for functional testing on a regular basis. The scope of the response will be specific for each process, with the level of response depending upon factors determined by the process operators. Response can be as simple as annunciating the condition at a monitoring station, or as dire as shutting down part or all of the process operation.
• Review every alarm event.
  Each alarm event should be logged and reviewed. Consider whether the event detection and response was adequate and beneficial. If the results were less than expected or desired, assess whether changes can be made to provide improved results in the future. The alarm plan is unlikely to be perfect in its first incarnation. Be prepared to reevaluate and make changes to improve performance.

The exercise of developing a comprehensive alarm plan will help to build understanding of process operation for all involved parties. This article is but a brief synopsis of the subject, intended to get the reader on the path of developing a useful alarm plan. Your alarm plan should an extension of process operation decision making, and have a goal of enhancing safety and reducing loss. Contact the process control and combustion specialists at Miller Energy for additional input.

Defending Industrial Control Systems From Cyber Attack

Cybersecurity is now a design element of all industrial
control systems

Industrial control system owners, operators, and other stakeholders should be aware of their exposure to malicious intrusion and attack by individuals or organizations intent on inflicting physical damage, stealing information, or generally wreaking havoc throughout an industrial operation. The risk of intrusion, regardless of the size or type of facility, is real and deserves the focused attention everyone involved in the design and operation of industrial control systems.

The National Cybersecurity and Communications Integration Center, part of the US Department of Homeland Security, ...

serves as a central location where a diverse set of partners involved in cybersecurity and communications protection coordinate and synchronize their efforts. NCCIC's partners include other government agencies, the private sector, and international entities. Working closely with its partners, NCCIC analyzes cybersecurity and communications information, shares timely and actionable information, and coordinates response, mitigation and recovery efforts. (from www.us-cert.gov/nccic)

The NCCIC has published a set of seven basic steps toward establishing a more secure industrial control system. I have included the publication below, and it is interesting and useful reading for all involved in industrial process control.

Having a fence around an industrial site, with a guarded entry gate, no longer provides the level of security needed for any industrial operation. Read the seven steps. Take other actions to build your knowledge and understanding of the risks and vulnerabilities. Cybersecurity is now another layer of design tenets and procedures that must be added to every control system. It will be a part of your company's best practices and success, now and in the future.

There are uncountable legacy controllers and communications devices throughout industrial America. All need to be reassessed for their vulnerability in the current and upcoming security environment. When reviewing your processes and equipment, do not hesitate to contact Miller Energy for assistance in your evaluation of our products.

NCCIC - Seven Steps for Achieving Cybersecurity for Industrial Control Systems from Miller Energy, Inc.

LOGIIC - Cybersecurity Confederation for Industry Video

Oil Refinery

In response to the challenges presented by malicious or mischievous cyber operatives, a number of organizations joined together to collaborate in the design, testing, and implementation of tools and techniques to protect critical industrial systems on a global scale. LOGIIC (Linking Oil and Gas Industry to Improve Cybersecurity), as its name implies, focuses on the oil and gas industry. We should all know, however, that a substantial portion of the automation and process control devices we regularly utilize throughout many industries today were originally developed in the oil and gas industry, where the operational scale and risk level are sufficiently high to justify the costs of developing new technology, methods, and equipment.

LOGIIC participants include the Automation Federation, which brings the resources of world class device and software manufacturers to bear on cybersecurity issues of the day. The Cyber Security Division of the Science & Technology Directorate in the US Department of Homeland Security is also involved. Currently, five major oil companies are members.

Since its inception, LOGIIC has successfully completed eight major projects, with plans for many more. Upon completion of selected projects, LOGIIC delivers public reports to help elevate best practices across the entire industry. Both the member companies and the government are putting funds towards these projects which benefits not only the private sector, but also the public interest. Companies are applying the results within their organizations, because it helps bridge the gap between information technology and the industrial-environment sides of the organization.

LOGIIC is an organization that conducts activities and disseminates information that can be useful throughout your own organization and that of your customers and suppliers in the industrial process control field. Below is a video highlighting the organization and its work.

Video Reenactment and Analysis of Explosion at Chemical Storage Facility

Unfortunate events can provide useful lessons for industrial
process operators

Industrial accidents range in severity and impact from minuscule to catastrophic. As operators, owners, or technicians involved with industrial operations, we all have a degree of moral, ethical, and legal responsibility to conduct our work in a manner that does not unduly endanger personnel, property, or the environment. Maintaining a diligent safety stance can be helped by 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 your 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 of an explosion that occurred in Texas in 2013, along with their findings regarding the cause of the incident. Check out the video and sharpen your senses to evaluate potential trouble spots in your own operation.

Contact Miller Energy for any safety related information you may need concerning their lines of industrial process control products.

New Product - Model R96 Non-Contact Radar Level Transmitter

New Model R96 Non-Contact Radar
Level Transmitter
Courtesy Magnetrol International

Magnetrol is a well known manufacturer of level and flow measurement instrumentation for the industrial process control field. The company recently released the Model R96 Non-Contact Radar Level Transmitter for applications where continuous fluid level measurement is required.

The company's description of the product...

"Virtually unaffected by the presence of vapors or air movement within a vessel’s free space, the two-wire, loop-powered, 6 GHz Radar transmitter measures a wide variety of liquid media in process conditions ranging from calm product surfaces and water-based media to turbulent surfaces and aggressive hydrocarbon media."

 The new product offers features that combine to make a state-of-art instrument for accurate continuous level measurement. A product brochure is included below. Contact application specialists to formulate the right product configuration for your level measurement challenge.

Non Contact Radar for Level Measurement and Control from Miller Energy, Inc.

Preparation of Control Valves For Oxygen or High Purity Service

Many valves can be specially prepared for high purity or oxygen service

Oxygen is used extensively throughout a wide range of industrial processes. Medical, deep-sea, metal cutting, welding, and metal hardening are a few examples. The steel industry uses oxygen to increase capacity and efficiency in furnaces. As a synthesis gas, oxygen is also used in the production of gasoline, methanol and ammonia.

Odorless and colorless, oxygen is concentrated in atmospheric air at approximately 21%. While O2, by itself, is non-flammable, it vigorously supports combustion of other materials. Allowing oils or greases to contact high concentrations of oxygen can result in ignition and possibly explosion. Oxygen service preparation of an industrial valve calls for special cleaning processes or steps that remove all traces of oils and other contaminants from the valve to prepare for safe use with oxygen (O2). Aside from the reactive concerns surrounding oxygen, O2 preparation is also used for applications where high purity must be maintained and valves must be free of contaminants.

Gaseous oxygen is noncorrosive and may be used with a variety of metals. Stainless steel, bronze and brass are common. Liquid oxygen presents unique challenges due to cryogenic temperatures. In this case, valve bodies, stems, seals and packing must be carefully chosen.

Various types of valves are available for oxygen service, along with a wide array of connections, including screwed, socket weld, ANSI Class 150 and ANSI Class 300, DIN PN16 and DIN PN40 flanged ends. Body materials include 316 stainless steel, monel, bronze and brass. Ball and stem material is often 316 stainless steel or brass. PTFE or glass filled PTFE are inert in oxygen, serving as a common seat and seal material employed for O2 service.

Common procedures for O2 service are to carefully deburr metal parts, then meticulously clean to remove all traces of oil, grease and hydrocarbons before assembly. Valve assembly is performed in a clean area using special gloves to assure no grease or dust contaminates the valve. Lubricants compatible with oxygen must be used. Seating and leakage pressure tests are conducted in the clean area, using grease free nitrogen. Specially cleaned tools are used throughout the process. Once assembled, the valves are tested and left in the open position. A silicone desiccant pack is usually inserted in the open valve port, then the valve ports are capped. A warning label about the desiccant pack's location is included, with a second tag indicating the valve has been specially prepared for oxygen service. Finally, valves are individually sealed in polyethylene bags for shipment and storage. Different manufacturers may follow slightly differing protocols, but the basics are the same. The valve must be delivered scrupulously contaminant free.

The O2 preparation of valves is one of many special production variants available to accommodate your special application requirements. Share your valve requirements and challenges with a valve specialist to get the best solution recommendations.

Process Automation: Valve Actuator Limit Switches

Municipal water treatment plant

Limit switches are devices which respond to the occurrence of a process condition by changing their contact state. In the industrial control field, their applications and product variations are almost countless. Essentially, the purpose of a limit switch is to serve as a trigger, indicating that some design condition has been achieved. The device provides only an indication of the transition from one condition to another, with no additional information. For example, a limit switch triggered by the opening of a window can only deliver an indication that the window is open, not the degree to which it is open. Most often, the device will have an actuator that is positively activated only by the design condition and mechanically linked to a set of electrical contacts. It is uncommon, but not unknown, for limit switches to be electronic. Some are magnetically actuated, though most are electromechanical. This article will focus on limit switch designs and variants used in the control and actuation of industrial process valves.

Employed in a wide range of industrial applications and operating conditions, limit switches are known for their ease of installation, simple design, ruggedness, and reliability.

Valves, devices used for controlling flow, are motion based. The movable portions of valve trim create some degree of obstruction to media flow, providing regulation of the passage of the media through the valve. It is the movement of critical valve trim elements that limit switches are used to indicate or control. The movable valve trim elements commonly connect to a shaft or other linkage extending to the exterior of the valve body. Mounting electric, hydraulic, or pneumatic actuators to the shaft or linkage provides the operator a means to drive the mechanical connection, changing the orientation or position of the valve trim and regulating the media flow. Because of its positive connection to the valve trim, the position of the shaft or linkage is analogous to the trim position and can be used to indicate what is commonly referred to as “valve position”. Limit switches are easily applied to the valve shaft or linkage in a manner that can provide information or direct functional response to certain changes in valve position.

In industrial valve terms, a limit switch is a device containing one or more magnetic or electrical switches, operated by the rotational or linear movement of the valve.

What are basic informational elements that can be relayed to the control system by limit switches? Operators of an industrial process, for reasons of efficiency, safety, or coordination with other process steps, may need answers to the following basic questions about a process control valve:

• Is the valve open?
• Is the valve closed?
• Is the valve opening position greater than “X”?
• Has the valve actuator properly positioned the valve at or beyond a certain position?
• Has the valve actuator driven the valve mechanism beyond its normal travel limits?
• Is the actuator functioning or failing?

Partial or complete answers to these and other questions, in the form of electrical signals relayed by the limit switch, can serve as confirmation that a control system command has been executed. Such a confirmation signal can be used to trigger the start of the next action in a sequence of process steps or any of countless other useful monitoring and control operations.

Applying limit switches to industrial valve applications should include consideration of:

• Information Points – Determine what indications are necessary or useful for the effective control and monitoring of valve operation. What, as an actual or virtual operator, do you want to know about the real time operational status of a valve that is remotely located. Schedule the information points in operational terms, not electrical switch terms.
• Contacts – Plan and layout a schedule of logical switches that will provide the information the operator needs. You may not need a separate switch for each information point. In some cases, it may be possible to derive needed information by using logical combinations of switches utilized for other discrete functions.
• Environment – Accommodate the local conditions and hazards where the switch is installed with a properly rated enclosure.
• Signal – The switch rating for current and voltage must meet or exceed those of the signal being transmitted.
• Duty Cycle – The cycling frequency must be considered when specifying the type of switch employed. Every switch design has a limited cycle life. Make sure your selection matches the intended operating frequency for the process.
• Auxiliary Outputs – These are additional contact sets that share the actuation of the primary switch. They are used to transmit additional signals with specifications differing from the primary signal.
• Other Actuator Accessories – Limit switches are often integrated into an accessory unit with other actuator accessories, most of which are related to valve position. A visual local indication of valve position is a common example.

Switches and indicators of valve position can usually be provided as part of a complete valve actuation package, provided by the valve manufacturer or a third party. It is recommended that spare contacts be put in place for future use, as incorporating additional contacts as part of the original actuation package incurs comparatively little additional cost.

Employing a properly configured valve automation package, with limit switches delivering valve status or position information to your control system, can yield operational and safety benefits for the life of the unit. Good advice is to consult with a valve automation specialist for effective recommendations on configuring your valve automation accessories to maximize the level of information and control.

Succeeding: Engineer as Peacemaker

Make Allies, Not Adversaries

Let's take a step away from the technical, but still focus on an important aspect of our work.

As engineers involved in process measurement and control, we are accustomed to everybody else looking to us for answers and solutions. We are the people that make things work. Occasionally the pressure and stress can get a little intense and strip away some of our civility in our dealings with those around us. You may have bitter experience with this as either victim or perpetrator. It never ends well. With a private and candid self-assessment about how we view and interact with other stakeholders in our projects, we may be able to scale down some of our stress and better focus on the reality of the task at hand. Consider the points below. Comment and add a few points of your own.

You are an expert, but so are they.

Accept that, just as you have specialized knowledge that others do not, they have specialized knowledge or insight you may lack. Encourage the sharing of knowledge with those you interface with on a project. Try to be proactive and ask gently probing questions to ascertain the comprehension level of others involved in the project in various roles. Their increased understanding of key project technical concepts will promote more effective communication throughout the duration of the project. It can also help to avoid missteps in your own progress. Good people appreciate the time you take to provide basic explanation of concepts they may not fully understand, but need to know. Make valuable allies of the other project stakeholders by freely contributing your expertise. It is an investment that costs you little, but may pay immense dividends at some future time.

Everybody else's job usually looks easier than it really is.

All jobs have their own special challenges and responsibilities that generate stress. Accept the notion that you probably do not fully comprehend the burdens on those around you. Your portion of the project is certainly critical, but no more so than that of anybody else. Everybody needs to perform or nobody succeeds. Try not to view your project tasks as compartmentalized, but rather as part of the combined joint effort of all stakeholders. Help out others whenever you can. Again, make allies.  

Everybody is somebody's customer.

Whomever you deliver your work product to is your customer. The people delivering their work to you should view you as their customer. Make your customers happy by adjusting aspects of your procedures to better satisfy their needs. In a more technical sense, your modified process output becomes an improved input to their process. Small changes in your delivery may produce comparatively large returns in customer satisfaction. Allies.

Do not embarrass or demean others...especially in public settings.

Embarrassment breeds anger, a desire for revenge, and other bad and unproductive things. Avoid words and deeds that will make a coworker or stakeholder look bad in front of others. If there is a problem, if there is a mistake, try to deal with it discreetly whenever possible. Giving a someone a chance to repair a mistake before it becomes public builds value in your relationship. Certainly, there can be instances where more is at stake than someone's pride. Use good judgement to recognize when you can privately give someone an opportunity to amend a situation without causing harm.

Reach a common understanding of project scope and technical details

Your organization's management or your company's client, whatever the case may be, will likely have project expectations which will be clearly understood in their mind, but perhaps not fully described to all those tasked with specific performance. It is also possible, even probable, these same stakeholders will have misconceptions or a lack of technical knowledge about certain facets of the project. Omissions from the project specs and gaps in the common understanding of technical aspects related to the work requirements can easily turn a fairly straight forward task into a wildfire of organizational mayhem. The way in which these situations are handled must be diplomatic. Injured egos can do more damage to project harmony and progress than the facts ever will. The delivery method for the facts will likely be more crucial than the facts themselves.

It's not about being right. It's about being successful.

At our company we recognize customers are more than merely people that buy things from us. They are people to whom we contribute our time and talent to help achieve their success,... which inevitably will lead to ours. Never hesitate to let us know how we are doing, or how we can help.

Industrial Control Systems Present Unique Cybersecurity Challenges

Industrial control systems have unique

cybersecurity challenges.

The International Society of Automation is offering a free white paper entitled “What Executives Need to Know About Industrial Control Systems Cybersecurity”. The article provides useful commentary and information that establishes the scope of cybersecurity in the industrial process control space and provides a basic framework for understanding how every process may be impacted by lax cybersecurity efforts. The author, Joseph Weiss, differentiates Industrial Control System (ICS) cybersecurity from that of organizational IT through a review of various attributes common to both types, including message confidentiality, integrity, time criticality, and more. Any reader’s awareness and understanding of the cybersecurity risks to their operation will be enhanced through this article. I finished reading the article wanting more on the subject, and ISA is certainly a resource for additional content.

A quote from the article...

“Cyber incidents have been defined by the US National Institute of Standards and Technology (NIST) as occurrences that jeopardize the confidentiality, integrity, or availability (CIA) of an information system.”

ICS cybersecurity extends beyond preventing malicious outside intruders from gaining access. It is an important part of maintaining the overall operating integrity of industrial processes. A holistic approach is advocated to identify physical risk factors to the process and its componentry (previous article on device protection), as well as vulnerabilities that may prevent exploitation by unauthorized parties. Weiss goes on to describe the role and qualifications of the ICS Cybersecurity Expert, essentially an individual that can function effectively as an IT cybersecurity tech with the added skills of an industrial control systems expert.

A synopsis of attack events is provided in the article, with the author’s conclusion that not enough is being done to secure industrial control systems and the risk exposure is substantial in terms of potential threats to personnel, environment, and economy. By providing your name and email address, you can obtain the white paper from the ISA website. Your time spent obtaining and reading the article will be well spent.

For any specific information or recommendations regarding our products and cybersecurity, do not hesitate to contact us directly. We welcome any opportunity to help our customers meet their process control challenges.

Cavitation - Scourge of Industrial Process Control Valves Everywhere

Cavitation produces bubbles in flowing process liquids

Consider a generic industrial fluid process control operation. There are pumps, valves, and other components installed in the process lines that, due to their interior shape or their function, cause changes in the fluid motion. Let's look specifically at control valves and how their throttling operation can create conditions able to greatly impact the valve itself, as well as the overall process.

Fluid traversing a control valve can undergo an increase in velocity when passing the constriction presented by the valve trim. Exiting the trim, fluid then enters the widening area of the valve body immediately downstream with a decrease in velocity. This change in velocity corresponds to a change in the kinetic energy of the fluid molecules. In order that energy be conserved in a moving fluid stream, any increase in kinetic energy due to increased velocity will be accompanied by a complementary decrease in potential energy, usually in the form of fluid pressure. This means the fluid pressure will fall at the point of maximum constriction in the valve (the vena contracta, at the point where the trim throttles the flow) and rise again (or recover) downstream of the trim.

This is where cavitation begins.

If the fluid being throttled is a liquid, and the pressure at the vena contracta is less than the vapor pressure of the liquid at the flowing temperature, portions of the liquid will spontaneously vaporize. This is the phenomenon of flashing. If, subsequently, the pressure of the fluid recovers to a level greater than the vapor pressure of the liquid, any flashed vapor will rapidly condense, returning to liquid. This collapse of entrained vapor is called cavitation.

Flashing, the generation of vapor bubbles within the liquid, will precede and set the stage for cavitation. When the flashed vapor bubbles condense to liquid they often do so asymmetrically, with one side of the bubble collapsing before the rest of the bubble. This has the effect of translating the kinetic energy of the bubble’s collapse into a high-speed “jet” of liquid in the direction of the asymmetrical collapse. These liquid “microjets” have been experimentally measured at speeds up to 100 meters per second (over 320 feet per second). What is more, the pressure applied to the surface of control valve components in the path of these microjets can be intense. An individual microjet can impact the valve interior surfaces in a very focused manner, delivering a theoretical pressure pulse of up to 1500 newtons per square millimeter (1.5 giga-pascals, or about 220000 PSI) in water. In an operating fluid system, this process can be continuous, and is known to be a significant cause of erosive wear on metallic surfaces in process piping, valves, pumps and instruments. As the rapid change in pressure takes place, the bubbles (voids in the liquid) collapse (implode), and the surrounding metal surfaces are repeatedly stressed by these implosions and their subsequent shock waves.

Consequences for control valves, as well as for the entire control process, vary and are often destructive. They may include:

• Loud noise
• Strong vibrations in the affected sections of the fluid system
• Choked flow caused by vapor formation
• Change of fluid properties
• Erosion of valve components
• Premature destruction or failure of the control valve 
• Plant shutdown

The video provides a visual demonstration, through clear piping, of what happens inside the piping system when a valve is operated in a manner that causes substantial cavitation.

The solution lies in minimizing the potential for cavitation to occur through proper valve selection and sizing, along with coordinating operating characteristics of pressure drop inducing components with the total system performance. One valve manufacturer's recommendations are summed up in four basic approaches.

• Avoidance of cavitation through proper valve selection. Use a valve with a rated liquid pressure recovery factor greater than that required for the application. Some applications may be suitable for the use of an orifice plate downstream of the valve.
• Cavitation Tolerant Components capable of withstanding limited amounts of cavitation without excessive wear. Increased flow noise is likely to accompany this route.
• Prevention of cavitation through the use of valve trim design that reduces pressure in several steps, avoiding excessive flashing. These valves can be expensive, but their effectiveness makes them an alternative worth considering.
• Containment of the harmful effects of limited to moderate cavitation through trim designs that eliminate contact of the fluid with metal surfaces which are more susceptible to damage.

Share your requirements and application challenges with a valve specialist and gain insight through their recommendations. Combining your process knowledge with their product application expertise will yield a great solution.

New Level Transmitter From Orion Instruments

Direct insertion and external mount versions of
Orion JM4 Magnetostrictive Level Transmitter
Courtesy Orion Instruments

Orion Instruments, a world class manufacturer of magnetic level indicators, level switches, and level transmitters, has released a new product for use in the industrial process measurement and control field. Their Jupiter Model JM4 magnetostrictive transmitter incorporates the company's many years of research, development, and field experience to provide a safer, simpler, and smarter transmitter for liquid level measurement and control.

The new model from Orion boasts level measurements with accuracy as high is +/-0.05" (1.27mm). The transmitter head can be rotated up to 310 degrees with an option for remote mounting. Variants are available for direct insertion or external mounting, with approvals for a number of area classifications. There are other valuable features to this series of level measurement instruments that reflect Orion's expertise in the field.

Browse the new product brochure included below. It provides illustrations of the product and its operating principle, along with dimensioned drawings and a listing of all the product options and variants. You can always obtain whatever information you need about Orion level measurement instruments from a product specialist. Share your liquid level measurement challenges and requirements with them for recommendations on the best solutions.

Orion Instruments Jupiter Magnetostrictive Level Transmitter from Miller Energy, Inc.

Coriolis Mass Flow Meter - Operating Principle, Applications, Advantages

Coriolis Flow Meter - Courtesy Yokogawa

Coriolis mass flow meters are widely used throughout the process measurement and control field. Their basic operating principle, combined with modern sensor and signal processing technology, provide a list of positive aspects.

Directly measure mass flow rate based on the principle of measurement.

Measure the mass flow rate with high accuracy of ±0.1%.

Provide a wide usable measurement range.

Deliver density measurement based on oscillating frequency.

Not materially impacted by fluid viscosity or density.

Coriolis flowmeters also do not need straight pipe sections upstream or downstream of the flowmeter. They also have the ability to measure non-conductive fluids. 

I have included an interesting video, produced by Yokogawa, a world class manufacturer of industrial process measurement and control instrumentation. It provides a clear and insightful illustration of the Coriolis principle and how it is used to provide accurate mass flow measurement.

Share your process measurement and control challenges with an instrumentation specialist. Combining your detailed process knowledge and their product application expertise will yield positive solutions.

Miller Energy Expanding Customer Connectivity With New Website Function

At Miller Energy, use website chat to connect directly with technicians
and product specialists.

Miller Energy will be rolling out real time chat on their website in early February. This new feature is another in a long line of continuous improvements the company has brought on line to better serve and connect with their customer base. On the desktop version, a chat widget will appear on every website page as a small tab on side of the display. A click of the widget will open a chat window and the visitor can type in their question or comment. Site visitors using mobile devices are afforded the same functionality.

Steve Collins, the Miller Energy website designer at CMS4i, commented on MEI's increased level of connectivity..

"The chat implementation at Miller Energy is notable because it connects customers directly with technically qualified employees that are part of the day to day company operations. Customers will be communicating with real “hands on” engineers and specialists familiar with process measurement and control, and engaged in the field on a daily basis."

Look for the chat function on the Miller Energy website in early February. Use it to get fast answers to your questions from knowledgeable and engaged industry professionals.

Pressure Relief Valve - Guardian of the Vessel

Pressure relief valves protect this industrial boiler
from conditions beyond maximum allowable working pressure

Danger and hazards are an integral part of industrial processes. The mitigation of these dangers and hazards, as well as reducing the probability of their occurrence, is the primary charge of industrial process engineering. Every product intended for use in a process control setting has safety and protection included in its design criteria. Pressure relief valves fall in that category of products designed and intended solely for safety purposes.

Manufacturers of what most generally refer to as pressure relief valves break the genre down into two distinct groups, relief valves and safety valves. One manufacturer, Anderson Greenwood (a Pentair brand), distinguishes the two valve types in their "Pentair Pressure Relief Valve Engineering Handbook"...

Relief Valve: A pressure relief valve characterized by gradual opening or closing generally proportional to the increase or decrease in pressure. It is normally used for incompressible fluids.

Safety Valve: A pressure relief valve characterized by rapid opening or closing and normally used to relieve compressible fluids.

The difference between the two valve types is found in their response to an excessive pressure condition. The relief valve, according to the definition, responds proportionally to the pressure increase, whereas the safety valve provides a non-proportional rapid response. Note also that the relief valve is generally intended for use with liquids (incompressible) and safety valves are commonly applied to compressible fluids, which would include steam and air.

Pilot Operated Pressure Relief Valve
Courtesy Anderson Greenwood

Pressure relief valves are found anywhere pressure is contained, be it a piping system, vessel, even a

household pressure cooker. The purpose of the relief or safety valve is to protect a pressurized system or vessel, should the system pressure exceed the maximum allowable working pressure. Simply put, keep it from breaking apart.

Because of the potentially catastrophic nature of a pressurized system failure, there is a high level of scrutiny, regulation, and testing focused on pressure relief and safety valves. The proper sizing and selection of the valves is also critical to providing proper function.

I have included a product bulletin from Anderson Greenwood with this article. Browse through it. It provides solid technical information, along with some excellent cutaway illustrations showing how the valves function. You are bound to discover something you did not know about safety and relief valves and their proper application. You can also contact the specialists at Miller Energy for assistance in proper valve sizing and selection.

Anderson Greenwood Pilot Operated Pressure Relief Valves from Miller Energy, Inc.