Showing posts with label temperature. Show all posts
Showing posts with label temperature. Show all posts

Alliance Technical Sales Wraps Up a Good Year

automated process control room
Alliance Technical Sales, like every other business, is finishing out 2017. Everyone at ATS is thankful for the support and opportunity provided by our customers and suppliers.

The company made some changes to its product lineup during the past year, expanding the range of application solutions available.

We also continued our program of product training and education to maintain top flight competence in recommending solutions to our customers' process measurement and control challenges.

Thank you, again. We look forward to the upcoming year and providing service to our customers at all levels.

Host Device Transmitters for Interchangeable Sensors

process measurement transmitter with wireless network connection to smart phone
Indigo 200 Series Transmitters accommodate an array of
smart sensors.
Image courtesy Vaisala
Our previous post was about Vaisala's new interchangeable humidity sensors in their Indigo line. The Indigo sensors, and other smart probes, are designed to work with the Indigo series transmitters to provide top flight performance in process measurement and control applications.

Transmitters enable plug-and-play setup with the smart sensors. Output options include analog, relay and Modbus. The browser based wireless interface allows configuration and viewing access to the transmitter. The LCD color display enables easy viewing on location.

Share your process measurement challenges with process instrumentation experts, leveraging your own process knowledge and experience with their product application expertise to develop the best solution.

Temperature and Humidity Data Logger

battery operated temperature and relative humidity data logger
The battery powered data logger has internal memory, or can
network with an external device.
Image courtesy Vaisala
Monitoring and maintaining records of process or storage space conditions can be an integral part of a quality assurance program or compliance with regulatory requirements. For temperature and humidity, the DL 2000 data logger from Vaisala provides a simple and effective total solution for monitoring and data logging.

The compact device operates on an internal battery with a 10 year life. Temperature and relative humidity sensors are on board, and a spare input channel allows connection of an additional analog sensor for a third measured parameter. A Boolean input allows another connection that can be used for a switch input to record an event.

When used with Vaisala software, data can be downloaded, displayed and analyzed. Multi-stage alarms can be implemented, and validation and mapping tasks completed. Customizable reports can be produced and exported to spreadsheets.

More technical data is provided in the datasheet included below. Share your data acquisition challenges with process measurement experts and leverage your own knowledge and experience with their product application expertise.

Match the Right Temperature Sensor Configuration to the Application

industrial temperature sensor or transmitter with welded pad for heat conduction
Using a temperature sensor properly configured for
the application will result in enhanced process performance
Image courtesy Smart Sensors, Inc.
There are more temperature controlled operations than any of us could count in a lifetime. Each one exhibits an exclusive set of performance requirements and design challenges. Matching the means of temperature measurement, the control loop characteristics, and heat delivery method to the application are essential to achieving successful operation.

Step one is to measure the process temperature. This sounds simple until you start researching products and technologies for measuring temperature. Like the temperature controlled operations mentioned previously, there are more than you can count in a lifetime. To filter the possible candidates for temperature sensing devices, consider these aspects of your application and how well a particular sensor may fulfill your requirement.

  • Response Time - How rapidly the sensor will detect a change in process temperature is a function of how the sensor is constructed and how it is installed. Most temperature sensors are enclosed or encapsulated to provide protection for the somewhat vulnerable sensing element. Greater mass surrounding the sensing element will slow sensor response. Whether the slower response time will adversely impact process operation needs to be considered. More consideration is due to the manner in which the temperature sensor assembly is installed. Not all applications involve a fluid in which the sensor assembly can be conveniently immersed, and even these applications benefit from careful sensor placement.
  • Accuracy - Know what your process needs to be effective. Greater levels of accuracy will generally cost more, possibly require more care and attention to assure the accuracy is maintained. Accuracy is mostly related to the type of sensor, be it RTD, thermocouple, or another type.
  • Sensitivity - Related to the construction, installation, and type of sensor, think of sensitivity as the smallest step change in process temperature that the sensor will reliably report. The needs of the process should dictate the level of sensitivity specified for the temperature sensor assembly.
Let's look at a very simple application.
Heat tracing of piping systems is a common application throughout commercial and industrial settings experiencing periods of cold weather. Electric heat trace installations benefit from having some sort of control over the energy input. This control prevents excessive heating of the piping or applying heat when none is required, a substantial energy saving effort. A temperature sensor can be installed beneath the piping's insulation layer, strapped to the pipe outer surface. One sensor design option available to improve the performance of the sensor is a surface pad. The surface pad is a metal fixture welded to the sensing end of a temperature sensor assembly. It can be flat, for surface temperature measurements, or angled for installation on a curved surface, like a pipe. The increased surface contact achieved with the surface pad promotes the conduction of heat to the sensor element from the heated pipe in our example. This serves to reduce and improve the response time of the sensor. Adding some thermally conductive paste between the pad and the pipe surface can further enhance the performance. While the illustration is simple, the concepts apply across a broad range of potential applications that do not allow immersion of the temperature assembly in a fluid.

A simple modification or addition of an option to a standard sensor assembly can deliver substantially improved measurement results in many cases. Share your temperature measurement requirements and challenges with a process measurement specialist. Leverage your own process knowledge and experience with their product application expertise.

Calibration of Process Instrumentation

sanitary rtd temperature transmitter
Industrial temperature transmitter requires
periodic calibration to assure reliable performance
Image courtesy of Smart Sensors
Calibration is an essential part of keeping process measurement instrumentation delivering reliable and actionable information. All instruments utilized in process control are dependent on variables which translate from input to output. Calibration ensures the instrument is properly detecting and processing the input so that the output accurately represents a process condition. Typically, calibration involves the technician simulating an environmental condition and applying it to the measurement instrument. An input with a known quantity is introduced to the instrument, at which point the technician observes how the instrument responds, comparing instrument output to the known input signal.

Even if instruments are designed to withstand harsh physical conditions and last for long periods of time, routine calibration as defined by manufacturer, industry, and operator standards is necessary to periodically validate measurement performance. Information provided by measurement instruments is used for process control and decision making, so a difference between an instrument’s output signal and the actual process condition can impact process output or facility overall performance and safety.

In all cases, the operation of a measurement instrument should be referenced, or traceable, to a universally recognized and verified measurement standard. Maintaining the reference path between a field instrument and a recognized physical standard requires careful attention to detail and uncompromising adherence to procedure.

Instrument ranging is where a certain range of simulated input conditions are applied to an instrument and verifying that the relationship between input and output stays within a specified tolerance across the entire range of input values. Calibration and ranging differ in that calibration focuses more on whether or not the instrument is sensing the input variable accurately, whereas ranging focuses more on the instrument’s input and output. The difference is important to note because re-ranging and re-calibration are distinct procedures.

In order to calibrate an instrument correctly, a reference point is necessary. In some cases, the reference point can be produced by a portable instrument, allowing in-place calibration of a transmitter or sensor. In other cases, precisely manufactured or engineered standards exist that can be used for bench calibration. Documentation of each operation, verifying that proper procedure was followed and calibration values recorded, should be maintained on file for inspection.

As measurement instruments age, they are more susceptible to declination in stability. Any time maintenance is performed, calibration should be a required step since the calibration parameters are sourced from pre-set calibration data which allows for all the instruments in a system to function as a process control unit.

Typical calibration timetables vary depending on specifics related to equipment and use. Generally, calibration is performed at predetermined time intervals, with notable changes in instrument performance also being a reliable indicator for when an instrument may need a tune-up. A typical type of recalibration regarding the use of analog and smart instruments is the zero and span adjustment, where the zero and span values define the instrument’s specific range. Accuracy at specific input value points may also be included, if deemed significant.

The management of calibration and maintenance operations for process measurement instrumentation is a significant factor in facility and process operation. It can be performed with properly trained and equipped in-house personnel, or with the engagement of subcontractors. Calibration operations can be a significant cost center, with benefits accruing from increases in efficiency gained through the use of better calibration instrumentation that reduces task time.

Technical Reference for Thermocouples and Reistance Temperature Detectors (RTD)

industrial temperature sensor transmitter with mounting flange and head
One of many industrial
temperature sensor
Smart Sensors, Inc.
Temperature measurement is probably employed in process control more than any other physical property measurement. Methodology for temperature measurement is well established, as is the industry providing instruments and devices for acquiring temperature data from almost any facet of any process. If you are even peripherally involved in process measurement and control, having a solid understanding of how thermocouples and RTDs work is a requisite to solving problems or servicing customers.

One manufacturer of a comprehensive line of thermocouple and RTD assemblies, Smart Sensors, Inc., produced a technical manual with all you need to know about temperature sensors for process measurement and control. The manual is included below for easy reference. It covers:

  • Thermocouple theory
  • RTD and thermocouple specification criteria
  • Cable specifications for both sensor types
  • Comparison of thermocouple and RTD attributes
  • Thermowell and protection tube specification and selection
  • Specifying temperature sensors for hazardous areas
  • Reference data tables for both sensor types
  • Practices for improving temperature measurement
  • Calibration
The tech manual should be on the shelf or cloud drive of anyone involved in accomplishing, interpreting, or maintaining temperature measurement. The configuration options for temperature sensor assemblies are extensive. Reach out to a product application specialist and combine your process knowledge with their product application expertise to develop effective solutions to temperature measurement challenges.

Combustion Control in Gas Turbines

gas turbine
Proper inlet air control can boost gas turbine efficiency
Gas turbines continue to enjoy an expansion in their use throughout the world. The benefits of using gas as a fuel are well recognized. Achieving high levels of fuel efficiency will be a goal of every operator, so understanding the nature of combustion and fuels can be useful in attaining optimum operating conditions.

Vaisala, a globally recognized leader in the measurement of temperature and humidity, was authored a white paper application note that explains how the temperature and humidity of inlet air can contribute to combustion efficiency, as well as providing recommendations for measuring these parameters in gas turbine applications.

The white paper is included below. Share your process measurement requirements and challenges with application experts. Combine your process knowledge with their product application expertise to deliver effective solutions.

Transformer Monitoring for Hydrogen, Moisture, and Temperature

transformer moisture hydrogen temperature monitor transmitter
Specialized transmitter for monitoring moisture,
hydrogen, and temperature levels in electrical
transformers. (Vaisala)
Electrical transformers are an intricate part of the power transmission and distribution system. Many transformers are insulated with mineral oil that also facilitates heat transfer for unit cooling. Abnormal thermal and electrical stresses, such as local overheating and electrical discharge ocurring in the transformer, cause decomposition of insulating oil and papers, resulting in production of a range of gases, one of which is hydrogen.

Routine dissolved gas analysis, or DGA, is performed on oil filled transformers to provide a measure of unit health. The process involves the extraction of an oil sample from the transformer, which is then subjected to laboratory analysis. The process is manual, time consuming, and only performed infrequently. It is known that the presence or increasing levels of certain gases is an indicator of internal faults or general wear and tear in a transformer. A reliable stream of data can provide value as a predictive indicator of overall transformer health and maintenance requirements. The endgame is to prevent unit failure and the resultant shutdown of connected customer equipment.

General recommendations call for trend monitoring of hydrogen. The rate of change in the concentration can be more indicative than the overall level in some cases. Any rapid change is a harbinger of potential problems. Adopting a proactive approach, based on transformer oil condition, can extend transformer useful life.

Moisture content of transformer oil is another concern. The presence of water boosts oil and paper insulation deterioration. Water presence in transformers generally has two potential sources, atmospheric and internal. The sources of moisture in the oil are not a subject of this article, but water reduces the dielectric strength of insulating oil and can facilitate corrosion or other material degradation within the transformer case.

Internal temperature is an indicator of the current operating condition of a transformer and is useful in evaluating its performance.

All three of the parameters mentioned, moisture, hydrogen, and temperature, are continuously measured by the new MHT-410 from Vaisala. The transmitter provides three isolated loop powered 4-20 mA outputs that provide the user with continuous data on moisture content, hydrogen concentration, and oil temperature. The compact unit installs easily in less than 30 minutes to provide online monitoring of insulating oil without any need for pumps, membranes, or sampling.

The new MHT410 provides real time transformer health monitoring, as well as information on transformer fault situations. You can find out more with a review of the data sheet included below. Reach out to a product specialist with your measurement challenges.

Temperature and Humidity Transmitters for Industrial Applications

Vaisala enjoys global recognition as a premiere provider of best-in-class humidity and temperature transmitters for industrial process measurement. The video provided here gives an excellent overview of the company's HMT 330 Series with all of its variants for special applications.

Share your temperature and humidity measurement challenges with product specialists, combining your process knowledge with their product application expertise to develop effective solutions.

PID Controller Action Simply Explained

industrial process PID controller
PID Process Controller
Courtesy Precision Digital
In the industrial control sphere, PID stands for "proportional plus integral and derivative control", three actions used together in managing a control loop. Process loop controllers use one, two or all three of these to regulate a process by responding in a prescribed fashion to disturbances in the process variable. PID control is used in a wide variety of applications in industrial control and process system management.

Many types of PID controllers exist on the market and are used for controlling temperature, pressure, flow, and just about every other process variable. Here is a brief explanation of the three actions that make up the PID algorithm, without the math.
PID control algorithm diagram
PID Control Loop Diagram
Proportional Control Action (P): The controller output responds in proportion to an error signal. Think of error as simply the distance between where you are and where you want to be. A larger error value will generate a larger output response from the controller. When the process value (the measured value of what is being controlled) is close to the setpoint, output response is reduced.

Integral Control Action (I): The control system will increase the output if the error is present over a period of time. This is called integral control action. The integral portion of the algorithm helps drive the process value to the setpoint if the process reaches some equilibrium point that is not the setpoint. The purpose of integral action is to provide adequate control response to varying demands of the process. Integral action does not function independently, requiring the inclusion of proportional action too.

Derivative Control Action (D): To achieve a stable process, wide proportional band and low integral action are often needed. Due to these settings, the control system can exhibit too slow a response pattern. If large system disturbances occur over a wide range, additional elements are needed in the control algorithm to provide suitable response. Derivative control action, added to the effect of proportional and integral, provides response to not only the magnitude of deviation, but also the rate of change of the error.

Modern PID loop controllers are often provided with a function that will automatically select the proper constants for the PID parameters. What used to be a very time consuming and tedious job can now be done with the push of a button and allowing the controller to "learn" the process dynamics. PID controllers minimize error and optimize the accuracy of any process.

Share your control challenges and requirements with product specialists and combine your process knowledge with their product expertise to produce the most effective results.

Humidity and Temperature Transmitters for Demanding Humidity Measurement

Vaisala Humidity sensors and transmitters for process measurement and control
HMT330 Series Humidity and Temperature Transmitters
Courtesy Vaisala
Humidity, the amount of water vapor in the atmosphere or a gas, can be an important measurable attribute of an industrial process. Many are aware of the measurement of relative humidity in HVAC applications and its impact on human comfort in occupied spaces, but the measurement of water vapor in air can be a required measuring point in many other processes that pose far greater challenge.

In addition to common wall or duct mounting applications, where the instrument is easily inserted or placed into the environment to be measured, there are applications that call for special adaptations to the instrument or sensing probe.
  • High pressure
  • Vacuum
  • High temperature
  • High humidity
  • Pressurized pipelines
  • Presence of chemical contaminants
Meeting the full range of industrial process control operations requires stable measurements and the choice of multiple configurations and options to customize the instrument to the process demands. Here are some features worth considering.
  • Multiple variants to match the basic process requirement
  • Full 0 to 100% humidity measurement range up to +180°C (+356°F)
  • PT 100 RTD for accurate temperature measurement
  • Pressure tolerance up to 100 bar
  • Superior sensor accuracy and stability
  • Graphic display and keypad for local operation
  • Multilingual user interface
  • Good chemical tolerance
  • Corrosion resistant housing
  • Delivered with multi-point NIST traceable calibration certificate
  • Analog outputs, RS232/485, WLAN/LAN
  • MODBUS protocol support (RTU/TCP)
  • Long term manufacturer warranty
While not all processes may require, or benefit from, the inclusion of all the listed features and capabilities, reviewing what is available and considering which features may provide better operability in your process can be beneficial. I have included a data sheet below that illustrates the HMT330 Series of humidity and temperature transmitters from Vaisala. Share your humidity measurement challenges with a product specialist. Combining your process knowledge with their product application expertise will produce solid solutions.