Topic: Temperature

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The Latest in Level
Level Sensors, Transmitters, Switches and More

Temperature and Pressure Resources You Can Use
Check Out The Latest Online Resources We Have Gathered for You on Temperature and Pressure Measuring Devices

Hot and Cold Running Temperature Information
The Editors of Control Tackle Industrial Temperature Devices in This Month's Resources Column

Taking Your Temperature
All the Tools You Need to Control the Heat

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White Papers: In Depth Research

Designing with Thermocouples: Get the Most from Your Measurements
Author: Phoenix Contact
Posted: 12/30/2012

More than 60 percent of all industrial temperature measurement applications in the U.S. use thermocouples. Despite their widespread use, there are many misconceptions about thermocouples.

This paper will discuss some of the basic technical issues that engineers need to consider when applying thermocouples.

Why use thermocouples?

Some common reasons for using thermocouples include:

• They're already used in your facility
• The application requires a sensor that can withstand a lot of physical stress or one that is physically small
• The expected high and low temperature ranges and/or total span exceeds the limitations of other sensor types
• Thermocouples are relatively inexpensive compared to some other sensors on the market

So how do you get the best possible thermocouple measurements? Although the thermocouple is a simple device, its small voltage signal is easily corrupted, and wiring one requires care.

How do thermocouples work?

Heat and electrical energy are related when it comes to electrical conductors, including thermocouple wires. A common misconception is that the thermocouple junction creates the voltage signal, similar to a battery. This is not true; rather, the signal is generated along the entire length of wire where there is a temperature gradient.

If you've ever held one piece of a wire, and then heated the other end, you quickly discovered that the heat moves up the wire. Why?

Heat moves toward the cold end because the higher kinetic energy of hot atoms imparts some of their energy to their colder neighbors, making them vibrate. The atoms vibrate faster toward the hot end. They don't move, however, because the solid structure holds the nucleus in place.

New Differential Pressure Sensor Incorporates LVDT Technology to Create More Environmentally-Resistant, Dependable and Economical Pressure Sensing Solution
Author: American Sensor Technologies
Posted: 11/14/2012
Differential pressure (dP) sensors with electronic signal processing are increasing being used to monitor flow, filter condition and level. Since these devices offer linear and accurate output, they are also replacing the differential pressure switch that only support on-off condition and useless for closed loop control system. These dPs are often configured with expensive valves and fluid filled remote seals for added protection against corrosive media, radiation and/or extreme media temperature ranges when operating in demanding environments. In cold ambient environment specially operating in temperatures below -4 deg F (-20 deg C), the sensor need to be heated either by trace heater or within a heated enclosure to maintain the operation of the dP sensor. In addition to being expensive, these valves and seals tend to be bulky and require time to install and maintain. In many critical applications such as food and pharmaceuticals, filled fluids are a serious concern due to process contamination. In gaseous systems such as hydrogen and oxygen and semiconductor applications, fluid filled sensors are being banned since the leakage of fluid into the process could lead to an explosion and serious safety issues.

A new series of LVDT (linear variable differential transformer) based oil-less dP sensor with dual channel ASIC (applications specific integrated circuit) have been developed that can operate in a wide range of corrosive materials, radiation and temperature without any oil filling and bulky sealing systems. By encapsulating LVDT proven technology with digital compensation, the pressure sensors combine the benefits of friction-free operation, environmental robustness and unlimited mechanical life. By selecting the diaphragm thickness and material properties, Table 1 show the dP ranges that can be produced using the LVDT technology.

Avoid Pitfalls in Precision Temperature Measurement
Author: Data Translation
Posted: 01/06/2010
Everyone is familiar with the concept of temperature in an everyday sense because our bodies feel and are sensitive to any perceptible change. But for more exacting needs as found in many scientific, industrial, and commercial uses, the temperature of a process must be measured and controlled definitively. Even changes of a fraction of a degree Celsius can be wasteful or even catastrophic in many situations.

For example, some biotech processes require elevated temperatures for reactions to occur and added reagents require exactly the right temperature for proper catalytic action. New alloys of metal and composites, such as those on the new Boeing 787 Dreamliner, are formed with high temperature methods at exacting degree points to create the necessary properties of strength, endurance, and reliability. Certain medical supplies and pharmaceuticals must be stored at exactly the desired temperature for transport and inventory to protect against deterioration and ensure effectiveness.

These new applications have driven the hunt for more exacting temperature measurement and control solutions that are easy to implement and use by both novice users and experienced engineers alike. This is a challenging task. However, new equipment and standards, such as LXI (LAN Extensions for Instrumentation) offer a methodology to perform these exacting measurements in test and control applications.

Many LXI devices are available on the market today. But, what do you need to know to select the best temperature measurement solution for your test and control application? This paper describes the common pitfalls of precision temperature measurement and what you need to consider before selecting a temperature measurement solution.

AMS2750D Temperature Uniformity Surveys Using TEMPpoint
Author: Data Translation
Posted: 01/06/2010
AMS2750D Temperature Uniformity Surveys using TEMPpoint.

Industrial process furnaces and ovens require uniform temperature and heating; This is critical to repeatable product performance from batch to batch. These furnaces require periodic inspection for temperature uniformity.

Electronic and Mechanical Calibration Services, Millbury Massachusetts characterizes temperature uniformity in industrial furnaces and ovens for their customers. This is accomplished by measuring temperature in several locations throughout the furnace and monitoring temperature with thermocouples over time according to AMS2750D specifications.

The customer previously used chart recorders which require constant monitoring while the survey is running. Surveys can run anywhere from 35 minutes to several hours long depending on the industry specified requirements. With the TEMPpoint solution the operator can set it up and let it run unattended, freeing them up to multitask their time and work more efficiently. The shipping TEMPpoint application required very little modification using Measure Foundry and now fulfills customer's requirements.

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Timeless Resources

Optimal temperature sensor selection There's no simple solution to achieving accurate temperature measurement. It’s a combination of knowing the inherent accuracy of particular sensor types, but also how environmental factors can create further measurement uncertainty and the sensor calibration techniques available to reduce this uncertainty.