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FIGURE 4. 1 Energy bands for solids
FIGURE Energy bands for solids. Only conduction-band electrons are free to carry current. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4.2 Metal resistance increases almost linearly with temperature.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE Line L represents a linear approximation of resistance versus temperature between T1 and T2. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4.4 Note the compensation lines in this typical RTD signal-conditioning circuit.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE Thermistor resistance versus temperature is highly nonlinear and usually has a negativeslope. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4.6 Divider circuit for Example 4.8.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE The Seebeck and Peltier effects refer to the relation between emf and temperature in a two-wire system. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE Practical measurements with a thermocouple system often employ extension wires to move the reference to a more secure location. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE These curves of thermocouple voltage versus temperature for a reference show the different sensitivities and nonlinearities of three types. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE A change of reference from 0°C to 20°C is equivalent to sliding the TC curve down in voltage. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE Automatic reference correction is now common in TC systems. Frequently thermistors or other solid-state temperature sensors are used for the reference measurement. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE Since TC voltages are small, great care must be taken to protect against electrical noise by using shielding, twisting, and differential amplification. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE A solid object experiences a physical expansion in proportion to temperature. Here the effect is highly exaggerated. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE A bimetal strip will curve when exposed to a temperature change because of different thermal expansion coefficients. Metal thickness has been exaggerated in this view. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4.15 Vapor-pressure curve for methyl chloride.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE Some solid-state temperature sensors operate like a zener diode whose voltage depends upon temperature. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4.17 One possible solution to Example 4.17.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4. 18 Circuit solution for Example 4. 18
FIGURE Circuit solution for Example Trimmer resistors are used to obtain nonstandard resistance values. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4.19 Vapor temperature-control process for Example 4.19.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4.20 One possible solution for Example 4.19.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4.21 One possible solution for Example 4.20.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4.22 Circuit for Problem 4.13.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4. 23 Electrical power from a lantern flame using thermocouples
FIGURE Electrical power from a lantern flame using thermocouples. See Problem S4.1. Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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FIGURE 4.24 Use of thermistors for measurement of wind speed in Problem S4.3.
Curtis Johnson Process Control Instrumentation Technology, 8e] Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.
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