Practical Considerations for Thermocouple Selection

Industrial Thermocouples, Fixed Bend Bayonet Type
Courtesy Wika

It would be difficult to chart a career course in the industrial process control field without being exposed to thermocouples. They are the ubiquitous basic temperature measuring tools with which all process engineers and operators should be familiar. Knowing how thermocouples work, how to test them, is essential. Sooner or later, though, you may be in charge of selecting a thermocouple for a new application. With no existing part in place for you to copy, what are the selection criteria you should consider for your process?

Thermocouple sensor assemblies are available with almost countless feature combinations that empower vendors to provide a product for every application, but make specifying a complete unit for your application quite a task. Let's wade through some of the options available and see what kind of impact each may have on temperature measurement performance.

• Thermocouple Type: Thermocouples are created using two dissimilar metals. Various metal combinations produce differing temperature ranges and accuracy. Types have standard metal combinations and are designated with capital letters, such as T, J, and K. Generally, avoid selecting a type that exhibits your anticipated measurements near the extremes for the type. Accuracy varies among thermocouple types, so make sure the accuracy of the selected type will be suitable.
• NIST Traceability: This may be required for your application. The finished thermocouple assembly is tested and compared to a known standard. The error value between the thermocouple shipped to you and the standard are recorded  and certified. The certified sensor assembly will be specially tagged for reference to the standard.
• Junction Type: If your sensor will be contained within a tube or sheath, the manner in which the actual sensor junction is arranged is important. The junction can be grounded to the sheath, electrically insulated from the sheath (ungrounded), or protruded from the sheath (exposed). If your process environment may subject the sensor assembly to stray voltages (EMF), it may be wise to stay away from a grounded junction, even though it provides fast response to a change in temperature. Exposed junctions provide very quick response, but are subjected to potential damage or corrosion from surrounding elements. The ungrounded junction provides protection within the enclosing sheath, with a slower response time than either of the other two junction types. When using ungrounded junctions, keep the mass and diameter of the sheath as small as might be practical to avoid overdamping the sensor response.
• Probe Sheath Material: This applies to assemblies installed in a tube or sheath which houses and protects the sensor junction and may provide some means of mounting. Material selections include a variety of stainless steel types, polymers, and metals with coatings of corrosion resistant material to suit many applications. Make sure the sheath material, including any coatings, will withstand the anticipated temperature exposure range.
• Probe Configuration: Sheath tube diameter and length can be customized, along with provisions for bends in the tube. Remember that as you increase the mass around the junction, or increase the distance of the junction from the point of measurement, the response time will tend to increase.



Industrial Thermocouples, Showing Various Termination Options
Courtesy Wika

• Fittings and Terminations: There are innumerable possibilities for mounting fittings and wiring terminations. Give consideration to ease of access for service. How will the assembly be replaced if it fails? Are vibration, moisture, or other environmental factors a concern? What type of cable or lead wires would be best suited for the application?

Your options are so numerous, it is advisable to consult a manufacturer's sales engineer for assistance in specifying the right configuration for your application. Their product knowledge and application experience, combined with your understanding of the process requirements, will produce a positive outcome in the selection procedure.

Expanded Hazardous Area Wireless Access Point Enclosure From Analynk

Hazardous Area Access Point Enclosure
Courtesy Analynk Wireless

As an engineer, I always welcome products that are well conceived, showing through their design and feature set that the developers really understand what I need to accomplish. Implementing industrial wireless communications in hazardous areas presents particular challenges to engineers responsible for achieving project goals of robust communications and safety. Analynk Wireless has developed several lines of products specifically targeted at wireless communications in hazardous areas, exhibiting a recognition of the needs of those responsible for providing industrial wireless communications in these specialized areas

Today, I am writing about Hazardous Area Access Point Enclosures, but recently have also written about two other Analynk products with which anyone involved with industrial wireless communications should become familiar. Check out New Antenna for Hazardous Area Wireless Communication and Cellular Device Data Links for Industrial Process Monitoring and Control (long titles, but short easily read articles).

Access point enclosures for hazardous areas must be specifically designed to accommodate the access point product selected by the customer....Cisco, Symbol, Meru, Aruba, Hewlett Packard, Motorola, and others. The matching enclosure for an access point will have:

• Custom mounting bracket mating to the customer's access point.
• UL listed enclosure for subject hazardous area, including antenna locations coordinated with access point device arrangement.
• UL listed explosion proof antenna, one or more as need for the subject access point.
• All hardware, mounting plate, and RF cables to simplify installation and startup

A product specialist can help you with the latest available information. Contact them to discuss your application and how to best fulfill your hazardous area wireless communication requirements.

New Antenna for Hazardous Area Wireless Communication - Updated With Data Sheet

Hazardous Area Antenna and Enclosure
Courtesy Analynk Wireless

Wireless communication has seen increasing prevalence in the industrial process measurement and control field for a number of years. Vendors, in response to customers' desire to incorporate the technology across an ever widening array of application scenarios, continue to develop and release new products and technologies that expand the potential for industrial wireless communication. One company, Analynk Wireless, is now shipping a new version of their patented wireless antenna for hazardous areas. We published an article last week about their cellular device data links.

Analynk Antenna
for Hazardous Areas
Courtesy Analynk Wireless

The newest Analynk Hazardous Area Antenna provides remote data links for customers using Iridium, GPS, and GLONASS. This new product adds to the company's already expansive line of wireless communication products specifically designed for industrial application, providing wireless data links to mobile or very remote locations not always accessible to other communication networks.

Analynk's antennas are operable across a very wide temperature range and provide substantial impact resistance, signal output, and ratings for hazardous environments.

Contact a product specialist about the Analynk Wireless products and discuss the potential benefits of incorporating or expanding wireless data links of all types into your operation.

Industrial Wireless Explosion Proof Antenna for Hazardous Area GPS/GLONASS/Iridium Satellites from MSJacobs-Cali

Cellular Device Data Links for Industrial Process Monitoring and Control

Wireless Transmitter and Receiver
Courtesy Analynk Wireless, LLC

Industrial process measurement and control is not restricted to the factory floor and fixed installations any longer. Increasingly, there are remote, as well as mobile, installations with a need for remote control command execution, or producing useful and valuable data that can be put to use by operational, safety, and financial stakeholders. Industrial process operators, as well as other levels of the business enterprise, can now have real time access to information that can be used for business and industrial process improvement.

The advent of wireless communications made gathering data from, and issuing control commands to, remote and mobile installations possible. A continuing path of vendor innovation and improvement has:

• Improved wireless technology reliability in the industrial setting.
• Expanded industrial wireless communications applicability.
• Simplified the implementation of a wireless communications strategy in an industrial process measurement and control setting.
• Reduced the cost and timeline associated with installation of a wireless solution.

Analynk Wireless, a designer and manufacturer of wireless devices and instrumentation for the process control industry, is adding newly designed cellular devices to their already extensive industrial wireless communications offering.  The deployed devices will feature cellular/GPS/GPRS connectivity to allow worldwide transmission and receipt of data via cellular and internet, providing remote monitoring and control through the use of additional connected devices.

The applications and opportunities for process improvement through wireless data gathering are vast. The cost and simplicity of these systems make them an option to be considered. More information is available from product specialists, with whom you can discuss your application ideas.

New Product From Cameron - CamCor Coriolis Flow Meters

CamCor Pro - Industrial Coriolis Flow Meter
Courtesy Cameron

Whether it's high viscosity crude oils, ultra-low flow conditions or applications at the extremes of temperature, Cameron's new CamCor™ range of Coriolis flow meters deliver value beyond the whole-life operational benefits associated with non-mechanical architectures.

CamCor comes in two architectures, CamCor CT for custody transfer, where the emphasis particularly is on high accuracy, and the Cameron CamCor PRO for process operations.

CamCor CT offers flow rate accuracy of ± 0.1% for liquids, as a result of its deep “U” shaped dual sensors, with outstanding zero stability performance (0.071 lb/min for 2” model). The range includes models purpose-designed for application extremes, covering temperatures from -200°C (Cryogenic/ LNG) up to 350°C. Nominal sensor sizes go from less than 2mm to 250mm, with 1/4” to 10” end connections, offered in ANSI class 150 to 900, other flange types, threaded, or Tri-Clover.

The unit is manufactured of 316/316L stainless steel and Hastelloy Alloy C22.

The CamCor PRO Series possesses a flow rate turndown ration up to 50:1, flow rate accuracy of
+/- 0.2% and density accuracy of +/- 0.003 g/ml. It comes with the same transmitter, output, communications, diagnostics and configuration as the CamCor CT and is available in four nominal sensor sizes, from 6mm to 50mm, with 1/2” to 2” end connections in ANSI flanges and Tri-Clover.

Review the product brochure below, or contact a product specialist for more details or a discussion of your application.

Coriolis Flow Meter - Cameron Camcor Brand from MSJacobs-Cali

New Stainless Steel Fuel Control Regulator From Fairchild

Cutaway of the Model 67
Precision Stainless Steel Fuel Control Regulator
Courtesy Fairchild Industrial Products

Fuel control is an essential and critical variable for engine and combustion testing. Fairchild Industrial Products Company has developed a stainless steel high precision fuel control regulator for use in engine testing. The new Model 67 combines durability, flexibility, and accuracy into a single product to improve your engine testing process. Some of the basic benefits:

High level of accuracy.

Reliability in engine under test fuel supply.

Stainless steel construction for wide range fuel suitability.

Constant output, even with fluctuating supply pressure or downstream pulsation.

Design allows for quick fuel changeover.

Washdown and internal purge capability.

Review the literature below and contact a product specialist for more detailed information, or to discuss your application.

Precision Stainless Steel Fuel Control Regulator - Fairchild Industrial Products Company from MSJacobs-Cali

Multivariable Vortex Flowmeter

Multivariable Vortex Flowmeter
Courtesy Azbil North America

A new multivariable vortex flowmeter has recently been added to the product line at MS Jacobs & Associates. It is intended for industrial process measurement and control. The AX Series, from Azbil North America, utilizes a vortex shedding velocity sensor, solid state pressure transducer, and resistance temperature detector in a single unit to allow accurate measurement of mass flow in gases, liquids and steam. The combination of multiple variable measurement in a single package simplifies installation and setup cost, while reducing potential leakage paths of an arrangement employing separate instruments for each variable. The AX Series is available for in-line or insertion installation. Your product sales engineer can provide a sizing guide and other assistance in selecting and configuring the best product for your application.

Azbil Mulitvariable Vortex Flowmeter from MSJacobs-Cali

Selecting the Right Valve Type - Gate Valves

When it comes to controlling flow in an industrial fluid handling system, there are more choices than you can count. The journey of focusing in on the best option for your application can be shortened by employing some coarse filters to the vast array of available products and technologies, discarding choices that do not meet the basic criteria deemed essential to a successful project.

A common type of industrial valve is the gate valve. It regulates fluid flow by sliding a round or rectangular wedge, known as the gate or disc, in the flow path of the fluid. When the gate is fully retracted from the fluid path, flow is enabled to its fullest. Gate valves close by sliding the gate, which is commonly attached to a threaded shaft of other similar mechanism, into the path of the flow until it is fully obstructed. It is the movement of the gate, combined with the way in which a gate valve is constructed, that attributes this valve class with its positive and negative values.

Positives for gate valves:

• When fully open, there is low resistance to fluid flow. The opening in the valve tends to mimic the cross sectional characteristics of connected piping and fluid can flow through the valve without a directional change.
• Changing the gate position (opening or closing the valve) does not require as much force or power as some other valve types, due to the gate movement being perpendicular to the flow direction.
• Gate valves work in both directions. The flow in the connected line can be reversed and the valve function is unimpaired.
• The gate valve assembly tends to be shorter in length along the path of flow than some other designs.



Gate Valves in Process Pipeline

• The rate of closure is generally slow, providing a graduated reduction in fluid movement and reduced physical shock to the piping system.

Operating or construction characteristics that may be an advantage to gate valve employment on one application may prove a disadvantage in another.

“Not so positives” for gate valves:

• When the valve is open, the seals are exposed to the fluid flow. Foreign material, even elements of the process fluid, can deteriorate or contaminate the seals and impact the sealing of the valve when closed.
• The gate valve opens at a comparatively slow rate, making it unsuitable for applications that may require rapid or immediate shutoff.
• The service and maintenance space requirements, often extending overhead of the valve, can be substantial and may impact the ability to locate the assembly where desired.
• Gate valves are not well suited for throttling fluid flow. Fluid flow through a partially open valve of this type may cause the gate to vibrate.

There are certainly more elements involved in proper valve selection than are shown here, but this quick check may help you focus on gate valves or another technology for further consideration. It is always beneficial to bring in experts and those with experience to participate in the selection process.

Guided Wave Radar to Lower Power Plant Costs

Reducing costs at power plants.

For most power plant operators, fuel expenditures account for seventy to eighty percent of production costs and millions of dollars per year. In fact improving heat rate one percent could generate five hundred thousand dollars an annual savings for five hundred megawatt power point.

To contain fuel costs, power plants must maximize the efficiency of their feed water heaters. That's why many companies today are focusing on improving heat rate as a way to use their feed water heaters more effectively, and significantly reduce their fuel costs.

Guided wave radar
principle of operation.

Heat rate is a measure of how efficiently a power plant uses heat energy. You can measure heat rate by the number of BTU’s your plant requires to generate a kilowatt hour of energy. As you're heat rate goes up so do you're fuel costs.

The condenser is the beginning of the feed water heaters process, where condensed steam from the feed water heater drains, and HP, IP and LP turbines is routed through successive feed water heaters. At the same time,  extractions steam from your turbines reaches the appropriate feed water heaters and the transfer of energy takes place.

Maintaining accurate and reliable level control throughout this cycle is critical to achieving the final feed water heater temperature that your process requires.

Let's take a closer look at how this works.  Feed water heaters use the heat of condensation to preheat water to the correct temperature for the boiler. During this process, shell and tube heat exchangers allow feed water to pass through the tube side and extract steam from the turbine to the shell side.

The primary benefit of this process is that the feed water heater decreases the fuel costs by using recovered energy, rather than costly hot gas, to heat the water.

Achieving optimum water level in a feed water heater is a critical component of maximizing energy transfer and minimizing controllable losses.

There are normally six to seven stages of feed water heating. Making an investment in level control can help you achieve optimum heat transfer and improved terminal temperature difference to provide a significant return on investment.

Guided wave radar
transmitter
(courtesy of
Magnetrol)

With a guided wave radar level control, you can optimize the condensing zone of your feed water heater to deliver accurate level control, maximize energy transfer, and minimize undue wear and tear. This can help you generate the savings needed to recover your investment.

Older level technologies, such as differential pressure, magnetostrictive, or RF capacitance and torque tubes are vulnerable to process conditions and induced instrument errors, such as shifts in specific gravity and mechanical or electronic drift.

In contrast, guided wave radar provides a truly reliable level measurement solution for feed water heaters. Guided wave radar performance is virtually unaffected by process variations and gives you a superior degree of accurate and reliable continuous level measurement without the need for calibration or gravity corrections.

With superior signal performance and advanced diagnostics, guided wave radar delivers premier level control for feed water heaters, as well as a broad range of challenging applications, such as condenser hot wells, deaerators, and cooling tower basins.

Combining a magnetic level indicator with guided wave radar merges the operating systems of a conventional flowed base magnetic level indicator with a leading edge solution. This allows you to effectively measure low dielectric media, high temperature, and high pressure process conditions and media, with shifting specific gravity and dielectric values accurately and repeatedly. The result is a diverse and redundant level measurement solution in a single chamber design.

For more information contact:

M.S. Jacobs and Associates
Phone: 800-348-0089
Fax: 412-279-4810
Email: msjacobs@msjacobs.com
www.msjacobs.com