The Flowserve Valtek Compressor Anti-Surge Valve

The Flowserve Valtek Compressor Anti-Surge Valve is a groundbreaking approach to anti-surge control by combining accurate control with exceptional responsiveness in a simple, reliable package. It is designed to address common challenges seen in compressor applications, where the surge of compressors can cause equipment failure and downtime. 

By providing rapid response, driving the valve open when required, and providing steady-state positioning when recycling, the Valtek Compressor Anti-Surge Valve solution protects the compressor from catastrophic surge damage. The Valtek Compressor Anti-Surge Valve also provides the benefits of fast and simple set-up as well as easy maintenance. In addition, to existing installations, the Logix 3800JF positioner is easily retrofitted.

For more infomration about Flowserve Valtek products in Florida, contact Instrument Specialties. Call them at 407-324-7800 or visit their website at https://isisales.com.

Instrumentation and Plant Safety Case Study: Refinery Explosion

A case study of the 2005 BP refinery explosion in Texas City, TX. This video recaps the events and circumstances leading up to a catastrophic explosion. Contributing factors include inadequate level and safety instrumentation, as well as breakdowns in safety monitoring and standard operating procedures. This video, courtesy of the Chemical Safety Board (csv.gov) is an excellent educational reference and should be viewed by engineering, maintenance, and plant management personnel everywhere.

Instrument Specialties, Inc.
http://isi.group
407-324-7800

Instrument Specialties: Providing Services that Drive Safety, Reliability and Performance

With engineering, design, and support resources available in Florida and the Caribbean, Instrument Specialties delivers value-added solutions that improve operations and increase profitability for our customers in the energy, municipal water, wastewater treatment, gas & oil, chemical, mining, agricultural, food service, pharmaceutical, and aerospace industries.

Instrument Specialties offers our customers a group of services designed to provide outstanding value and cost savings throughout your equipment's life span. By integrating access to best-in-breed equipment manufacturers, decades of application experience, and state-of-the-art tools, Instrument Specialties helps customers:

• Improve plant and personnel safety
• Optimize asset uptime and performance 
• Lower total cost of operation and maintenance
• Increase equipment reliability

PARTS, REPAIRS, UPGRADES AND FIELD SERVICES

Instrument Specialties mobile service personnel and advanced diagnostic technologies, along with the unparalleled expertise of their technicians, is equipped to address virtually any process equipment service requirement, regardless of the manufacturer.

Repair and Upgrades — Instrument Specialties repairs and/or upgrades equipment, providing new life to existing process instrumentation, valves, and control systems.

Replacement Parts and Components — Using its broad network of manufacturer's service facilities, and our own local stocking centers, Instrument Specialties provides timely delivery of quality parts that keep your operations running smoothly and profitably .

Field Service Personnel — From maintenance to management, highly qualified Instrument Specialties project managers, engineers and technicians will assist you in keeping your plant running smoothly .

ENGINEERING AND TECHNICAL SERVICES

Technical Analysis — Instrument Specialties can perform system audits to identify operational issues that may be constraining output or elevating operating costs, and then recommended laser-focused solutions.

Reliability and Efficiency Services — Instrument Specialties lends their decades of hands-on experience to offer practical solutions that improve the performance, efficiency, and reliability of your process control equipment - all while lowering your total cost of ownership.

Loop Design, Integration and Engineering Support — Instrument Specialties engineers engage with our customers, providing on-site support for grassroots project planning, system design, or project management requirements.

ASSET MANAGEMENT AND OPTIMIZATION

Instrument Specialties continues to invest in its capabilities and technologies to help our customers realize more payback from their plant assets.

Equipment Life Cycle Optimization — Through a combination of on-site assessments and technology, ISI experts help customers benchmark operational performance, define key metrics, and implement precise solutions to achieve long-term operational goals.

Intelligent Product Solutions — By employing an array of sophisticated products, services, and software that collects, examines and understands data, Instrument Specialties helps customers use predictive analytics to take action and improve asset reliability and reduce downtime.

EDUCATION AND TRAINING

Instrument Specialties offers a wide range of innovative training programs to help plant operators, managers, reliability specialists, engineers and maintenance staff further develop their understanding of critical equipment and processes.

Training at ISI — At our state-of-the-art facility in Sanford, Florida, highly trained instructors provide hands-on training and instruction in the principles of process control, instrumentation maintenance, control valve operation, and equipment reliability.

Customer On-site Training — Instrument Specialties will design, develop, and deliver training programs tailored specifically around the people, equipment and processes at a customer’s facility.

Instrument Specialties, Inc.
http://isi.group
407-324-7800

Instrument Specialties, Inc. - ISI Technical Group

Instrument Specialties is in the business of helping customers improve and implement their processes and applications. A professional agency with a focused, creative, and aggressive staff, ISI takes a long term relationship approach to business.

https://www.isisales.com
407-324-7800

Continuous In-Line Measurement of Process Liquid Viscosity

In-line process viscosity measurement system.
Image courtesy Krohne, Inc.

Among the many analytical instruments from Krohne is the Viscoline process viscosity measurement system. It provides continuous in-line measurement of process liquid viscosity.

Krohne describes the operating principle...

The fluid flows through a continuous pipe containing two low pressure drop static mixers. The sensor device measures the pressure drop at both static mixers by means of two differential pressure measurements: ΔP1 and ΔP2. Precise pipe flow rate measurement is obtained from the integrated KROHNE OPTIMASS 7000 straight tube Coriolis meter which is uniquely insensitive to fluid viscosity effects. From the two pressure drop measurements and the flow rat reading, the fluid flow parameters are processed in the system, and the pipeline viscosity is determined. A temperature reading can be useful for thermal correction when a reference measurement is required. Such correction requires laboratory thermal characterization or dual measurement.

For solutions to your process measurement and control challenges, share them with an instrumentation specialist. Leverage your own process knowledge and experience with their product application expertise.

In-Line Process Viscosity Measurement from Instrument Specialties, Inc.

Sight Flow Indicators

Sight flow indicators give operators a rapid and direct
means of verifying process flow.
Image courtesy Clark Reliance - Jacoby-Tarbox

Industrial process operations involving fluids benefit greatly from advanced instrumentation and measure, but there may be instances where a visual confirmation or assessment of fluid flow is useful or necessary. In those cases, a direct reading sight flow indicator is just the thing needed to fill the requirement.

The sight flow indicator is essentially a clear window or tube with an encasement and appropriate connections that facilitate its installation into a process piping system. It is installed in a manner that provides an operator visual access to the inside of the piping at that location. Further details about construction materials, armoring, and more will round out the product selection that best accommodates the industrial environment, the media, and the visual inspection needs.

Jacoby-Tarbox manufactures a range of  fluid processing and measurement products, including sight flow indicators, for industrial use. Their sight flow indicators, available in a broad range of line sizes and connections, enable a process operator to get that all important visual inspection of liquid or gaseous media flow in real time. The presence, color and character of the media can be assessed visually through the flow indicator, delivering visual confirmation of some targeted aspect of the process.

Share your process flow and level measurement challenges with instrumentation specialists, leveraging your own knowledge and experience with their product application expertise to develop an effective solution.

Sight Flow Indicators With Flanged Connection from Instrument Specialties, Inc.

Vortex Flowmeters

Multivariable vortex flowmeter combines flow, temperature
and pressure measurement into a single compact instrument
Image courtesy Krohne

Vortex shedding flowmeters provide process operators with consistent fluid flow rate measurements across a wide range of applications. These flowmeters measure the volumetric flow rate of steam, gas, and low viscosity liquids, boasting both versatility and dependability when used in conjunction with process systems.

Vortex shedding refers to the phenomenon wherein flowing gas or liquid form vortices around a solid object placed in the flow path. The measurement technology returns an indication of the process fluid velocity, which can then be used to provide volumetric or mass flow data. Vortex technology is well suited for many applications involving cryogenic liquids, hydrocarbons, air, and industrial gases. Vortex flow measurement requires contact between portions of the measurement instrument and the process media, so these flowmeters are commonly fashioned from a range of corrosion resistant materials.

The process of measuring the flow involves both the flowmeter and the ability for other instrumentation to measure the vortices themselves in order to calculate velocity. Ultrasonic sensors have become popular tools for measuring vortices. Applications involving flow measurement of high viscosity fluids are not suited for vortex technology because extremely viscous fluids do not behave in the same manner as lower viscosity fluids when their flow path is obstructed. Splitting higher viscosity fluids into concordant vertices is extremely difficult due to the internal friction present in highly viscous liquids.

Additionally, in order to split these process liquids, the piping through which the process material flows must be straight, and any disturbance or vibration in the pipe may impact the measurement. A vortex flowmeter will be in a fixed installation. This stationary element, operating without electrodes, can be advantageous for flow measurement in chemical applications utilizing low viscosity fluids.

The vortex shedding flowmeter is widely used for the measurement of steam flow. The high pressure and elevated temperature of steam, along with the variation that exists in most steam systems, have little negative impact on the operation of a vortex flowmeter. Vortex shedding flowmeters are often volumetrically based in terms of measurement, but their output can be combined with other fluid information to calculate mass flow. A product variant commonly available will combine the vortex flow measurement with temperature and pressure compensation, delivering three process measurements from a single installed device.

Share your process and flow measurement challenges with instrumentation specialists, leveraging your own knowledge and experience with their product application expertise.

Pressure Switch Design Details

Industrial process control applications present dynamic and varied requirements for measuring, monitoring and control. Each point calls for specific evaluation of the information needed from the process point for use in monitoring process performance, or control to be applied at the process point to regulate an outcome. Sometimes, a continuous analog signal is needed to provide indication across a range of values. Other times, it is only necessary to have notification of, or take action when, a certain temperature or pressure related event occurs. In those cases, a simple and reliable device can adequately meet the project requirements.

Pressure and differential pressure switches connect to a process and change their switch position when a setpoint condition is reached. The are simple to understand, easy to install, low in cost, and require little maintenance of attention. The switches are available in an extensive array of configurations, with options to fill out almost any application requirement.

SOR, Inc., globally recognized manufacturer of temperature and pressure switches, has produced this video outlining some of the distinctive features of their pressure switches for industrial process control applications. Share your process measurement and control requirements and challenges with product application specialists, and leverage your own process knowledge and experience with their product expertise to develop effective solutions.

Eight Selection Criteria for Control Valves

Control valve shown with actuator and positioner
Image courtesy Flowserve - Valtek

Proper selection with respect to a number of factors plays an important role in obtaining the desired performance from a control valve. Failure to make a properly considered selection can impact operation, productivity and safety. Here is a quick checklist of basics that need to be considered:

• Control valves are not intended to be a an isolation valve and should not be used for isolating a process. 
• Always carefully select the correct materials of construction. Take into consideration the parts of the valve that comes in to contact with the process media such as the valve body, the seat and any other wetted parts. Consider the valve's exposure to operating pressures and temperatures. Finally, also consider the ambient atmosphere and any corrosives that can occur and effect the exterior of the valve. 
• Put your flow sensor upstream of the control valve. Locating the flow sensor downstream of the control valve exposes it to an unstable flow stream which is caused by turbulent flow in the valve cavity.
• Factor in the degree of control you need and make sure your valve is mechanically capable. Too much dead-band leads to hunting and poor control. Dead-band is roughly defined as the amount of control signal required to affect a change in valve position. It is caused by worn, or loosely fitted mechanical linkages, or as a function of the controller setting. It can also be effected by the tolerances from mechanical sensors, friction inherent in the the valve stems and seats, or from an undersized actuator. 
• Consider stiction. The tendency for valves that have had very limited travel, or that haven't moved at all, to "stick" is referred to as stiction. It typically is caused by the valves packing glands, seats or the pressure exerted against the disk. To overcome stiction, additional force needs to be applied by the actuator, which can lead to overshoot and poor control.
• Tune your loop controller properly. A poorly tuned controller causes overshoot, undershoot and hunting. Make sure your proportional, integral, and derivative values are set). This is quite easy today using controllers with advanced, precise auto-tuning features that replaced the old fashioned trial and error loop tuning method.
• Don't over-size your control valve. Control valves are frequently sized larger than needed for the flow loop they control. If the control valve is too large, only a small percentage of travel is used (because a small change in valve position has a large effect on flow), which in turn makes the valve hunt. This causes excessive wear. Try to always size a control valve at about 70%-90% of travel.
• Think about the type of control valve you are using and its inherent flow characteristic. Different types of valve, and their disks, have very different flow characteristics (or profiles). The flow characteristic can be generally thought of as the change in rate of flow in relationship to a change in valve position. Globe control valves have linear characteristics which are preferred, while butterfly and gate valves have very non-linear flow characteristics, which can cause control problems. In order to create a linear flow characteristic through a non-linear control valve, manufacturers add specially designed disks or flow orifices which create a desired flow profile.

These are just a few of the more significant criteria to consider when electing a control valve. You should always discuss your application with an experienced application expert before making your final selection.

Inside Look at Multichannel Refractometer User Interface

K Patents, globally recognized manufacturer of process refractometers for liquid analysis, offers a multichannel user interface providing connectivity for up to four refractometers. The model MI provides environmental protection and industrial computing and intelligence to deliver maximum performance and ease of use. The company provides this list of primary features.

• High-performance, industrial computing system
• Expandable system and connectivity for up to four (4) PR-43-G refractometers and eight (8) I/O modules
• Environmentally sealed IP67, Type 4X (door closed), IP 66 (door open), rugged 316 stainless steel enclosure. Also for demanding field and outdoor conditions (-40−50°C, -40−122°F)
• Prism wash diagnostics and control
• Trend display that shows one or two graphs over a selected period of time.
• Embedded measurement apps: The apps are small programs that give different types of measurement data and functionality
• Modules, e.g. mA-output and mA-input module
• 10” graphical touchscreen color display
• 21 CFR 11 compliant user identification and management, electronic data records and data-logging, event log/audit trail.

The video provides a visual tour of the interface and behind the panel layout. Share your industrial liquid process analysis challenges with process measurement experts. Leverage your own knowledge and experience with their product application expertise to develop effective solutions.

Signal Splitter Solves Multiple Device Connection Challenge

Selecting the right I/O modules can solve signal
transmission challenges.
Image courtesy Acromag

Industrial process measurement and control requires the transmission of signals from point to point with no significant distortion. Even with the growing prevalence of wireless signal transmission, over-wire transmission of signals is still a primary means of connecting one device to another.

In the cabled process measurement and control world, the 4 to 20 milliampere signal is generally considered the standard for transmitting analog control and measurement signals over any distance.There is an immense array of instrumentation and controllers available for use with 4-20 mA signals, so expertise in routing and delivering those signals should be part of your process measurement and control skill set.

Like just about everything else, routing 4-20 mA signals presents its own set of challenges that require some thought and planning to overcome. Electrical interference is always a concern and must be prevented from impacting the operation of measurement and control devices. Additionally, there must be sufficient power in the signal loop to accommodate the resistance load of connected devices. There are other considerations, but I'm going to focus on these two.

One scenario that can present significant issues is multiple devices requiring connection to the same signal, but with great distance between them. A simple solution can be implemented using an isolated signal splitter.

Features of these units making them an attractive, single box, solution:

• One 4-20 ma input channel for the measuring or controlling device.
• The input signal is retransmitted as identical isolated 4-20 ma signals
• Galvanic isolation from input to output
• Isolation between channels for safety and increased noise immunity. Fault in one output channel does not impact the operation of the other channels.
• Reliable operation in industrial environments, with protection from RFI, EMI, ESD, and surges.
• Low radiated emissions in accordance with CE requirements. 
• DIN-rail mounting of the unit
• Plug-in terminal blocks

If you have a very long signal loop, connecting multiple devices, consider breaking the devices into two groups that may allow for a substantially shorter cable length for each group. Connect each group to one of the isolated outputs of the splitter, giving each group of instruments the identical signal without the risks or impractically of an excessively long cable run.

There are other devices available that may combine special characteristics that solve your signal transmission and processing challenges. Contact a product specialist and discuss your existing or anticipated project requirements. Combine your process knowledge and experience with the extensive product knowledge of a professional sales engineer and produce the best possible outcome.

Loop Powered Isolated Signal Transmitters and Splitters from Instrument Specialties, Inc.

Instrument Specialties is Ready to Help Hurricane Impacted Partners

 

Industrial Instrumentation, Valves

and Municipal Equipment

Instrument Specialties is Ready to Help

As our Florida industry partners rebuild, ISI offers special emergency services for your plant. 

As we Floridians begin to recover from the damage of Hurricane Irma,  ISI Technicians & Field application support engineers, are available to you.  We have support personnel located in all major metropolitans areas including: Orlando, Miami, Ft. Myers, Tampa, Lakeland, and Jacksonville.

During September ISI will waive most emergency and expedited service fees, related to our products, for hurricane related issues. These include:

• Technical Field Support
• Emergency Onsite Field Support
• Evaluation and Testing Fees

We are here for you, and ready to help get your plant up and running ASAP.

Contact Info: Instrument Specialties Inc.: 3885 St. Johns Parkway Sanford, FL 32771 Phone: 407.324.7800 Fax: 407.324.1104 Email: Click Here

Video of Valtek Packing Subassembly

The Mark One, from the Flowserve brand Valtek, is a globe valve intended for flow control of liquids or gases across a wide range of applications. The valve design provides high positioning accuracy, repeatability and tight shutoff. A wealth of special design and construction features make the Mark One a serious contender for almost any fluid control operation.

Share your control valve and valve automation requirements and challenges with an application specialist, combining your own process knowledge and experience with their product application expertise to develop an effective solution.

Control Valve Flow Characteristics

Industrial Control Valve
Courtesy Flowserve - Valtek

Flow characteristics, the relationship between flow coefficient and valve stroke, has been a subject of considerable debate. Many valve types, such as butterfly, eccentric disk and ball valves, have an inherent characteristic which cannot be changed (except with characterizable positioner cams). Flow characteristics of globe valves can be determined by the shape of the plug head.

The three most common types of flow characteristics are quick opening, equal percentage and linear. The adjacent figure shows the ideal characteristic curve for each. These characteristics can be approximated by contouring the plug. However, inasmuch as there are body effects and other uncontrollable factors, plus the need for maximizing the flow capacity for a particular valve, the real curves often deviate considerably from these ideals. When a constant pressure drop is maintained across the valve, the characteristic of the valve alone controls the flow; this characteristic is referred to as the “inherent flow characteristic.” “Installed characteristics” include both the valve and pipeline effects. The difference can best be understood by examining an entire system.

Control valve flow properties
Courtesy Flowserve - Valtek

Equal Percentage

Equal percentage is the characteristic most commonly used in process control. The change in flow per unit of valve stroke is directly proportional to the flow occurring just before the change is made. While the flow characteristic of the valve itself may be equal percentage, most control loops will produce an installed characteristic approaching linear when the overall system pressure drop is large relative to that across the valve.

Linear

An inherently linear characteristic produces equal changes in flow per unit of valve stroke regardless of plug position. Linear plugs are used on those systems where the valve pressure drop is a major portion of the total system pressure drop.

Quick Open

Quick open plugs are used for on-off applications designed to produce maximum flow quickly.

This information provided courtesy of Flowserve Valtek. Share your control valve requirements and challenges with a valve specialist, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

High Performance Butterfly Valves

Valdisk High Performance Double Offset Butterfly Valve
Courtesy Flowserve - Valtek

Industrial process control applications can present stringent and challenging performance requirements for the physical equipment and components that comprise the process chain. The valves employed in fluid based operations need to be resistant to the impact of extreme fluid conditions, requiring careful design and selection consideration to assure proper performance and safety levels are maintained in a predictable way.

Industrial valves intended for extreme applications are generally referred to as severe service or high performance valves. While there are plenty of published and accepted standards for industrial valves, one does not exist to precisely define what constitutes a severe service valve.

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

• Extreme media or environmental temperature or pressure
• High pressure drop operation that may cause cavitation
• Rapid or extreme changes to inlet pressure
• Certain types or amounts of solids contained in the fluid
• Corrosive media

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

There are numerous manufacturers of severe service or high performance valves, each with specialized product offerings focusing on a particular performance niche. Flowserve, under their Valtek brand, manufactures the Valdisk high performance butterfly valves ranging from NPS 2-52 and ASME class 150, 300, 600, 900, 1500 pressure ranges. The valve design is ideal for manual or automated actuation, installed with a manual hand gear, electric actuator, or a pneumatic actuator. Seats are available as soft or metal on this double offset butterfly valve that provides tight closure for bi-directional flow. Construction materials include carbon steel and stainless steel. A range of options and variants are available to customize the valve build to suit a replacement or new installation.

There is more information available about the Valtek high performance offering. You can always get more information and discuss your special requirements with a valve specialist. They have application experience and access to technical resources that can help with selecting the right valve components to meet your severe service and high performance applications.

Combating Cavitation in Industrial Process Control Valves

Cavitation in liquid processes produces bubbles which can
damage valves.

In process control valves, cavitation results from a rapid drop in pressure as liquid passes through the valve. It results in the formation of vapor spaces or bubbles within the valve cavity. When the bubbles move downstream into a larger cross-sectional area, velocity decreases and pressure increases. The higher pressure now surrounding the bubbles causes them to implode, producing shockwaves which propagate through the liquid. These shockwaves can cause metal fatigue and excessive wear on the internals of the valve. The collapsing bubbles also make a discernible sound with accompanying vibration. The cumulative effects of cavitation can cause rapid deterioration of a valve, resulting in reduced control function, frequent need for service, or premature failure.

There are ways to mitigate cavitation. Some involve changes in the process, others, incorporating a properly designed and selected valve with trim that reduces or prevents the conditions that cause cavitation. The paper below, authored by Flowserve, provides an in depth examination of the causes of cavitation, then continues with explanation of how their specialty valves are designed to overcome the conditions that promote it.

There are detailed illustrations showing the specific valve trim features that impede cavitation. Share your process control valve challenges with application experts, combining your process knowledge with their product application expertise to develop effective solutions.

Cavitation Control in Industrial Valves from Instrument Specialties, Inc.

Computational Fluid Dynamics Applied to Effective In-Tank Mixing

Jacoby Tarbox uses computational fluid dynamics software to reliably and predictably model the performance of their eductors used to accomplish mixing in tanks, open vessels, and other containers. The video provides an overview of how the company determines the arrangement of eductors that will provide the mixing performance required by each customer.

Share your interest or application challenges with a product application specialist, combining your process knowledge with their product application expertise to develop effective solutions.

Achieving Close Control of Process Temperature

Temperature sensor type, construction, and
location contribute to system performance
Courtesy Krohne

Temperature control is a common operation in the industrial arena. Its application can range across solids, liquids, and gases. The dynamics of a particular operation will influence the selection of instruments and equipment to meet the project requirements. In addition to general performance requirements, safety should always be a consideration in the design of a temperature control system involving enough energy to damage the system or create a hazardous condition.

Let's narrow the application range to non-flammable flowing fluids that require elevated temperatures. In the interest of clarity, this illustration is presented without any complicating factors that may be encountered in actual practice. Much of what is presented here, however, will apply universally to other scenarios.

What are the considerations for specifying the right equipment?

KNOW YOUR FLOW

First and foremost, you must have complete understanding of certain characteristics of the fluid.

• Specific Heat - The amount of heat input required to increase the temperature of a mass unit of the media by one degree.
• Minimum Inlet Temperature - The lowest media temperature entering the process and requiring heating to a setpoint. Use the worst (coldest) case anticipated.
• Mass Flow Rate - An element in the calculation for total heat requirement. If the flow rate will vary, use the maximum anticipated flow.
• Maximum Required Outlet Temperature - Used with minimum inlet temperature in the calculation of the maximum heat input required.

MATCH SYSTEM COMPONENT PERFORMANCE WITH APPLICATION

• Heat Source - If temperature control with little deviation from a setpoint is your goal, electric heat will likely be your heating source of choice. It responds quickly to changes in a control signal and the output can be adjusted in very small increments to achieve a close balance between process heat requirement and actual heat input.
• Sensor - Sensor selection is critical to attaining close temperature control. There are many factors to consider, well beyond the scope of this article, but the ability of the sensor to rapidly detect small changes in media temperature is a key element of a successful project. Attention should be given to the sensor containment, or sheath, the mass of the materials surrounding the sensor that are part of the assembly, along with the accuracy of the sensor.
• Sensor Location - The location of the temperature sensor will be a key factor in control system performance. The sensing element should be placed where it will be exposed to the genuine process condition, avoiding effects of recently heated fluid that may have not completely mixed with the balance of the media. Locate too close to the heater and there may be anomalies caused by the heater. A sensor installed too distant from the heater may respond too slowly. Remember that the heating assembly, in whatever form it may take, is a source of disturbance to the process. It is important to detect the impact of the disturbance as early and accurately as possible.
• Controller - The controller should provide an output that is compatible with the heater power controller and have the capability to provide a continuously varying signal or one that can be very rapidly cycled. There are many other features that can be incorporated into the controller for alarms, display, and other useful functions. These have little bearing on the actual control of the process, but can provide useful information to the opeartor.
• Power Controller - A great advantage of electric heaters is their compatibility with very rapid cycling or other adjustments to their input power. A power controller that varies the total power to the heater in very small increments will allow for fine tuning the heat input to the process.
• Performance Monitoring - Depending upon the critical nature of the heating activity to overall process performance, it may be useful to monitor not only the media temperature, but aspects of heater or controller performance that indicate the devices are working. Knowing something is not working sooner, rather than later, is generally beneficial. Controllers usually have some sort of sensor failure notification built in. Heater operation can be monitored my measurement of the circuit current.

SAFETY CONSIDERATIONS

Any industrial heater assembly is capable of producing surface temperatures hot enough to cause trouble. Monitoring process and heater performance and operation, providing backup safety controls, is necessary to reduce the probability of damage or catastrophe.

• High Fluid Temperature - An independent sensor can monitor process fluid temperature, with instrumentation providing an alert and limit controllers taking action if unexpected limits are reached.
• Heater Temperature - Monitoring the heater sheath temperature can provide warning of a number of failure conditions, such as low fluid flow, no fluid present, or power controller failure. A proper response activity should be automatically executed when unsafe or unanticipated conditions occur.
• Media Present - There are a number of ways to directly or indirectly determine whether media is present. The media, whether gaseous or liquid, is necessary to maintain an operational connection between the heater assembly and the sensor.
• Flow Present - Whether gaseous or liquid media, flow is necessary to keep most industrial heaters from burning out. Understand the limitations and operating requirements of the heating assembly employed and make sure those conditions are maintained.
• Heater Immersion - Heaters intended for immersion in liquid may have watt density ratings that will produce excessive or damaging element temperatures if operated in air. Strategic location of a temperature sensor may be sufficient to detect whether a portion of the heater assembly is operating in air. An automatic protective response should be provided in the control scheme for this condition.

Each of the items mentioned above is due careful consideration for an industrial fluid heating application. Your particular process will present its own set of specific temperature sensing challenges with respect to performance and safety. Share your requirements with temperature measurement and control experts, combining your process knowledge with their expertise to develop safe and effective solutions.

Use Electronic Pressure Controllers in Your Research Process Loop to Eliminate Droop, Boost, and Hysteresis

(re-blogged with permission from Brooks Instrument)

Gas pressure control is critical in many applications like life sciences and chemical/petrochemical research where flow is an integral part of the process. Brooks Instrument electronic pressure controllers can be used as they require flow to function. Compared to using a mechanical pressure regulator, electronic pressure controllers eliminate droop, boost and hysteresis, offering stable pressure control.

There are two configurations available for pressure control – upstream and downstream. This terminology is somewhat unique to Brooks Instrument electronic pressure controllers.

Downstream vs. Upstream Pressure Control

Downstream pressure controllers maintain the pressure downstream of the device itself, increasing flow to increase the pressure and decreasing flow to decrease the pressure. For this reason, this is called direct acting. This configuration is commonly called a standard pressure regulator. A downstream pressure controller acts very similar to a typical mass flow controller because they are both direct acting.
Upstream pressure controllers maintain the pressure upstream of the device itself, increasing flow to reduce the pressure and decreasing flow to increase the pressure. For this reason, this is called reverse acting. This configuration is commonly called a back pressure regulator in the industry.

Selecting and Sizing an Electronic Pressure Controller

The following information is required to select and size a Brooks Instrument electronic pressure controller:

• Process gas
• Maximum flow rate being used to maintain pressure -The “sweet spot” for pressure control is between 100 SCCM and 5 SLPM.
• Calibration pressure (maximum pressure to be controlled)
• Reference pressure (for upstream controllers the reference pressure is the downstream pressure and for downstream controllers the reference pressure is the upstream pressure)

As long as flow is present in a process you will typically find the need for some type of pressure control. Vessel sizes up to 30 liters commonly use flow rates up to 3 SLPM during their process steps. Brooks Instrument pressure controllers are a perfect fit for these services, offering stable pressure control with no droop, boost or hysteresis, which are commonly experienced when using a mechanical pressure regulator.

Typical Bioreactor Process Using an Upstream Pressure Controller

Fundamentals of Radar Technology for Level Gauging

RADAR Level transmitter
courtesy of KROHNE

The term “radar” is generally understood to mean a method by means of which short electromagnetic waves are used to detect distant objects and determine their location and movement. The term RADAR is an acronym from “RAdio Detection And Ranging”.

A complete radar measuring system is comprised of a transmitter with antenna, a transmission path, the reflecting target, a further transmission path (usually identical with the first one), and a receiver with antenna. Two separate antennas may be used, but often just one is used for both transmitting and receiving the radar signal.

Measuring the level of liquids or solids in vessels is a frequent requirement in industry. RADAR level measurement is the use of a radar signal is emitted via an antenna, reflected from the surface of the product and the echo received again after a time interval “t”.

The document below, courtesy of KROHNE, is an excellent technical reference for a strong understanding of RADAR level measurement.

Fundamentals of Radar Technology for Level Gauging from Instrument Specialties, Inc.