18-12-2012, 03:04 PM
A Seminar Report On MOISTURE MEASUREMENT
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INTRODUCTION
Public concepts of how to share and manage the finite supplies of water are changing. Increasing competition exists between power, irrigation, municipal, industrial, recreation, aesthetic, and fish and wildlife uses. Within the United States, critical examinations of water use will be based on consumption, perceived waste, population density, and impact on ecological systems and endangered species. Water districts will need to seek ways to extend the use of their shares of water by the best available technologies. Best management measures and practices without exception depend upon conservation of water. The key to conservation is good water measurement practices.
Moisture analysis covers a variety of methods for measuring moisture content in both high level and trace amounts in solids, liquids, or gases. Moisture in percentage amounts is monitored as a specification in commercial food production. There are many applications where trace moisture measurements are necessary for manufacturing and process quality assurance. Trace moisture in solids must be controlled for plastics, pharmaceuticals and heat treatment processes. Gas or liquid measurement applications include dry air, hydrocarbon processing, pure semiconductor gases, bulk pure gases, dielectric gases such as those in transformers and power plants, and natural gas pipeline transport.
MOISTURE
Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, fruit, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at saturation. It can be given on a volumetric or mass (gravimetric) basis.
Moisture refers to the presence of a liquid, especially water, often in trace amounts.
Small amounts of water may be found, Diffuse wetness that can be felt as vapor in the atmosphere or condensed liquid on the surfaces of objects; dampness.
for example- in the air (humidity), in foods, and in various commercial products.
ELECTRICAL METHODS
There are mainly three major types of electrical methods. They are as follow-
1. Microwave method
2. Capacitive method
3. Resistive method
MICROWAVE METHOD
One of the properties of microwaves is the ability to travel through non conductive materials.In materials with bipolar molecular structure, (i.e. water), the electric field of microwaves can induce oscillations whilst travelling through the medium. During this process, the micro waves lose some of their energy. This loss in energy increase with the amount of water that medium contains, with the result that as the water concentration increase, less energy will reach the other side of the medium. Water not only absorbs but also reflects some of the micro wave energy. By utilizing these two effects (reflection and absorption) one is able to perform moisture measurements with micro wave techniques.
CAPACITIVE METHOD
Capacitive sensing has gained increasing importance in the last decades and is successfully
Employed in various applications in industrial and automotive technologies. Due to the high
relative permittivity of water (Er,water of about 80), capacitive techniques are typically well-suited for moisture measurement in bulk solids .
[attachment=44221]
INTRODUCTION
Public concepts of how to share and manage the finite supplies of water are changing. Increasing competition exists between power, irrigation, municipal, industrial, recreation, aesthetic, and fish and wildlife uses. Within the United States, critical examinations of water use will be based on consumption, perceived waste, population density, and impact on ecological systems and endangered species. Water districts will need to seek ways to extend the use of their shares of water by the best available technologies. Best management measures and practices without exception depend upon conservation of water. The key to conservation is good water measurement practices.
Moisture analysis covers a variety of methods for measuring moisture content in both high level and trace amounts in solids, liquids, or gases. Moisture in percentage amounts is monitored as a specification in commercial food production. There are many applications where trace moisture measurements are necessary for manufacturing and process quality assurance. Trace moisture in solids must be controlled for plastics, pharmaceuticals and heat treatment processes. Gas or liquid measurement applications include dry air, hydrocarbon processing, pure semiconductor gases, bulk pure gases, dielectric gases such as those in transformers and power plants, and natural gas pipeline transport.
MOISTURE
Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, fruit, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at saturation. It can be given on a volumetric or mass (gravimetric) basis.
Moisture refers to the presence of a liquid, especially water, often in trace amounts.
Small amounts of water may be found, Diffuse wetness that can be felt as vapor in the atmosphere or condensed liquid on the surfaces of objects; dampness.
for example- in the air (humidity), in foods, and in various commercial products.
ELECTRICAL METHODS
There are mainly three major types of electrical methods. They are as follow-
1. Microwave method
2. Capacitive method
3. Resistive method
MICROWAVE METHOD
One of the properties of microwaves is the ability to travel through non conductive materials.In materials with bipolar molecular structure, (i.e. water), the electric field of microwaves can induce oscillations whilst travelling through the medium. During this process, the micro waves lose some of their energy. This loss in energy increase with the amount of water that medium contains, with the result that as the water concentration increase, less energy will reach the other side of the medium. Water not only absorbs but also reflects some of the micro wave energy. By utilizing these two effects (reflection and absorption) one is able to perform moisture measurements with micro wave techniques.
CAPACITIVE METHOD
Capacitive sensing has gained increasing importance in the last decades and is successfully
Employed in various applications in industrial and automotive technologies. Due to the high
relative permittivity of water (Er,water of about 80), capacitive techniques are typically well-suited for moisture measurement in bulk solids .