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AN-S // Temperature Sensors
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RdF Surface Temperature Sensors
V. Typical Applications
Figure 5: Container, Specimen, Stikon Thermocouple

1. Biological Sensor (Figure 5)

Biological samples are often frozen for future use. A few examples are:


The freezing of cancer cells for future research.


The freezing of skin tissue removed from cadavers for grafts on burn patients.


The freezing of animal sperm for future insemination and special breeding.

Living tissue is primarily water and as it freezes the water will expand, causing friction in the cells and possibly destroying the specimen. For this reason it is extremely important to carefully control the freezing rate. An RdF Stikon® thermocouple can be used for this application. A Type “T” thermocouple is chosen because it has published limits of error below 0°C. It is attached to the specimen container and is immersed into a cooling solution. Due to the low thermal mass of the thermocouple bead it can accurately follow the cooling process of the specimen. After the temperature of the sample is stabilized it can be moved to a storage area and the thermocouple can be removed for use on another container. In this case a pressure sensitive silicone adhesive can be used easily.

Figure 6: Mold Body, Cavity, Foil T/C Sensor (Adhesive Mount)

2. Mold Temperature Sensor (Figure 6)

The manufacturer of molded plastic cases needs to measure temperature inside the mold. This measurement was used to indicate variations in temperature and to control cycle rates which optimize production and reduce rejects. Due to the complex design of the mold, the use of a typical immersion sensor would require major modifications and prove costly. Also, the normal thermal mass of conventional thermocouple sensors prohibits the sensor from indicating true mold temperature. A foil thermocouple can be attached to a wall in the molding cavity and due to its extremely small thermal mass will respond rapidly to any changes. This style sensor is easy to install and the lead wires can be routed between various parts on the mold assembly.

Figure 7: Sensor, Structural Support

3. Structural Measurements (Figure 7)

The manufacturer of sophisticated military jet aircraft needs to measure many temperatures on various structures during test flights. These measurements will help detect design flaws and optimize performance on prototype aircraft before production begins. The sensor must have a very wide temperature range because temperatures can vary from 500°F near the engines to subzero at the wing tips. The sensor must also have very low mass and not affect the normal function of even extremely small parts. A polyimide insulated flexible sensor such as RdF Model 22810 is ideal for this type measurement. The polyimide thermally stable material and the sensor with lead wires weighs less than 6 grams. The Teflon® insulated lead wires are easily terminated to connectors or instrumentation. Both Teflon® and polyimide are chemically resistant to most fuels, solvents, hydraulic fluids, cleaning agents and other chemicals used in the aerospace industry. These sensors are also easily installed using conventional epoxy adhesives.

Figure 8: Steam, Heavy Duty Surface Sensor, Boiler Tubes

4. Boiler Tube Measurements (Figure 8)

Boiler tubes carry high temperature water under extreme pressures. These tubes are generally bundled in tight configurations with little clearance. Due to the fact that flow restrictions affect boiler performance and the lack of clearance between tubes, the best way to obtain a temperature measurement is by an external surface measurement. RdF Sensor Models 22802 or 26881 are ideal for this type of application. The sensing pad can be formed by RdF to mate with the radius of the tubes. The sensor can be clamped or welded to the tube and lead wires can be routed to connection points beyond the tube bundle. These sensors are now a permanent part of the installation and are rugged enough to withstand unintentional abuse during normal maintenance.

Figure 9, Fluid, Strapon Sensor

5. Energy Management (Figure 9)

With the high cost of today's energy an energy management system has become a necessity for most large facilities. When installing these systems in older buildings, temperature measurements are required on pipes that were installed when the building was originally built. The contractor does not know the material or condition of this piping and is reluctant to do any machining for fear of fractures or failures that would require extensive repair. The Strapon® style sensor, RdF Models 22393 or 26393 equipped with a pipe clamp are ideal for this application. The clamp can be chosen to fit the appropriate pipe size. The sensor can be installed in tight areas by people with no prior training. This easy installation makes it ideal as a permanent measurement or for a temporary measurement for setting up the system.



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