-
Construction Of Critical Temperature Alarm System
CHAPTER ONE -- [Total Page(s) 2]
Page 1 of 2
-
-
-
CHAPTER ONE
INTRODUCTION
A sensor is a device that measures a
physical quantity and converts it into a signal which can be read by an
observer or by and instrument. For example, a mercury-in-glass
thermometer converts the measured temperature into expansion and
contraction of a liquid which can be read on a calibrated glass tube. A
thermocouple converts temperature to an output voltage which can be read
by a voltmeter. For accuracy, all sensors need to be calibrated against
known standards.
A sensor is a device which receives and responds to
a signal or stimulus. Here the term “stimulus†means a property or a
quantity that needs to be converted into electrical form. Hence, sensor
can be defined as a device which receives a signal and converts it into
electrical form which can be further used for electronic devices.
Sensor
sensitivity indicates how much the sensor’s output mercury in a
thermometer moves 1 cm when the temperature changes by 1°C, the
sensitivity is 1cm/°C. Sensors that measures very small changes by
changes must have very high sensitivities. Sensors also have impact on
what they measure; for instant, a room temperature thermometer inserted
into a got cup of liquid cools the liquid while the liquid heats the
thermometer. Sensors need to the designed to have a small effect on what
is measured; making the sensor smaller often improves this and may
introduce other advantages.
CLASSIFICATION OF MEASUREMENT ERRORS
A good sensor obeys the following rules:
1) It’s sensitive to the measure property;
2) It’s insensitive to any other property;
3) It does not influence the measured property.
Ideal
sensors are designed to be linear. The output signal of such a sensor
is linearly proportional to the value of the measured property. The
sensitivity is then defined as the ratio between the output signal and
measured property. For example if a sensor measures temperature and has a
voltage output, the sensitivity is a constant with the unit [V/K]. This
sensor is linear because the ratio is constant at all points of
measurement.
CHAPTER ONE -- [Total Page(s) 2]
Page 1 of 2
-
-
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---
