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Construction Of Critical Temperature Alarm System
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TYPES OF TEMPERATURE MEASUREMENT SENSORS
1) THERMOCUPLE TEMPERATURE MEASUREMENT SENSORS:
Thermocouple
consists essential of two strings or wire made of different metals and
joined at one end. Changes in the temperature at the juncture induce a
change in electromotive force (emf) between the other ends. As
temperature goes up, this output emf of the thermocouple rises, though
not necessarily linear.
2) RESISTANCE TEMPARATURE DEVICES (RTD)
Resistive
temperature devices capitalize on the fact that the electrical
resistance of a material changes as its temperature changes. Two key
types are the metallic devices (commonly referred to as RTD) and
thermistor.
As their name indicates, RTD rely on resistance change in
a metal with the resistance rising more or less linearly with
temperature. Thermistors are based on resistance change in a ceramic
semi conductor. The resistance drops nonlinearly with temperature rise.
3) INFRARED TEMPERATURE MEASUREMENT DEVICES
Infrared sensors are non-contacting devices. They infer temperature by measuring the thermal radiation emitted by a material.
4) BIMETALLIC TEMPERATURE MEASUREMENT DEVICE
Bimetallic
device takes advantage of the difference, if rate of thermal expansion
between different metals strips of two metals are bonded together. When
heated one side will expand more than the other and the resulting
bonding is translated into a temperature reading by mechanical linkage
to a pointer.
5) FLUID EXPANSION TEMPERATURE MEASUREMENT DEVICES
Fluid-expansion
devices, typified by the household thermometer, generally come in two
main classifications: the measuring type and the organic-liquid type.
Versions employing gas instead of liquid are also available. Mercury is
considered an environmental hazard, so there are regulations governing
the shipment of devices that contain it. Fluid-expansion sensors do not
require electric power. They do pose explosion hazards, and are stable
even after repeater cycling.
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ABSRACT - [ Total Page(s): 1 ]The term “critical point†is sometimes used to denote specifically the vapour-liquid critical point of a material. The vapour-liquid point denotes the condition above which distinct liquid and gas phases so not exist.The project, the construction of critical temperature measuring instrument is aimed at measuring the critical point substances thereby obtaining its liquid-vapour critical temperature and pressure for a selected substance.The chapter one of this project gave a brief ... Continue reading---
