1. Temperature is a measure of the hotness or coldness of an object and can be defined as either the condition of a body that determines the transfer of heat or the degree of hotness referenced to a specific scale.
2. Heat is the energy that flows to a body and causes its temperature to increase, melt, boil, or undergo other changes. Common units for measuring heat include the British Thermal Unit (BTU) and the calorie.
3. Thermometers use various principles and materials to measure temperature, including the expansion of liquids in glass tubes, the bending of bimetallic strips, and changes in electrical resistance of materials like platinum and thermistors.
This document discusses various methods of temperature measurement. It begins by explaining that temperature is a subjective concept that requires objective measurement using thermometers. It then describes common temperature scales like Fahrenheit, Celsius and Kelvin.
The document discusses several methods of temperature measurement including expansion thermometers like liquid-in-glass thermometers and bimetallic thermometers which measure the expansion of materials. It also discusses electrical temperature instruments like resistance thermometers, thermocouples and thermistors which measure changes in electrical resistance or voltage with temperature. The construction and working of liquid-in-glass thermometers and resistance thermometers are explained in detail.
Rankine cycle is a thermodynamic cycle that converts heat into work. It uses a water/steam as the working fluid. There are three main types: ideal, reheat, and regeneration. The ideal cycle assumes instantaneous and reversible processes while real cycles are non-reversible. The reheat cycle increases efficiency by reheating steam between turbine stages. The regeneration cycle further improves efficiency by using steam extracted from the turbine to preheat feedwater entering the boiler. Together these modifications help maximize work extraction from high-temperature heat sources like fossil fuels.
This document provides an overview of conventional and modern heat pipes. It discusses the basic working principles of heat pipes, including how heat is transferred from the evaporator to the condenser via evaporation and condensation of a working fluid. It also describes the key components of heat pipes - the container, working fluid, and wick structure. Finally, it outlines several types of heat pipes such as thermosyphons, loop heat pipes, micro heat pipes, and variable conductance heat pipes.
Basic Mechanical Engineering- Hydraulic turbinesSteve M S
The document discusses different types of hydraulic turbines used to convert hydraulic energy from falling or flowing water into mechanical energy. It classifies turbines based on the type of energy at the inlet as either impulse turbines (only kinetic energy) or reaction turbines (both pressure and kinetic energy). It describes the Pelton wheel and Francis turbine as examples of each type. It further classifies turbines based on the main flow direction and provides ranges for suitable head based on specific speed. In summary, the document provides an overview of common hydraulic turbine classifications and examples like the Pelton and Francis turbines used for high and medium heads respectively.
This document provides an introduction to heat transfer and thermodynamics concepts. It discusses how heat transfer is related to thermodynamics and distinguishes between different forms of energy. The three main modes of heat transfer are conduction, convection and radiation. Heat is defined as the transfer of energy between two systems due to a temperature difference, and will flow from the higher temperature object to the lower temperature one. The document provides objectives and outlines concepts like thermal energy, mechanisms of heat transfer, Fourier's law of conduction and applications of heat transfer.
This document provides information about a group project to design an impulse turbine. The group leader is Abdul Jabbar and the other 7 group members are listed. It then provides details about turbines in general and impulse turbines specifically. It discusses the classification, working principle, parts, and efficiency of impulse turbines. It also compares impulse turbines to reaction turbines and lists the advantages and disadvantages of impulse turbines.
This document discusses various methods of temperature measurement. It begins by explaining that temperature is a subjective concept that requires objective measurement using thermometers. It then describes common temperature scales like Fahrenheit, Celsius and Kelvin.
The document discusses several methods of temperature measurement including expansion thermometers like liquid-in-glass thermometers and bimetallic thermometers which measure the expansion of materials. It also discusses electrical temperature instruments like resistance thermometers, thermocouples and thermistors which measure changes in electrical resistance or voltage with temperature. The construction and working of liquid-in-glass thermometers and resistance thermometers are explained in detail.
Rankine cycle is a thermodynamic cycle that converts heat into work. It uses a water/steam as the working fluid. There are three main types: ideal, reheat, and regeneration. The ideal cycle assumes instantaneous and reversible processes while real cycles are non-reversible. The reheat cycle increases efficiency by reheating steam between turbine stages. The regeneration cycle further improves efficiency by using steam extracted from the turbine to preheat feedwater entering the boiler. Together these modifications help maximize work extraction from high-temperature heat sources like fossil fuels.
This document provides an overview of conventional and modern heat pipes. It discusses the basic working principles of heat pipes, including how heat is transferred from the evaporator to the condenser via evaporation and condensation of a working fluid. It also describes the key components of heat pipes - the container, working fluid, and wick structure. Finally, it outlines several types of heat pipes such as thermosyphons, loop heat pipes, micro heat pipes, and variable conductance heat pipes.
Basic Mechanical Engineering- Hydraulic turbinesSteve M S
The document discusses different types of hydraulic turbines used to convert hydraulic energy from falling or flowing water into mechanical energy. It classifies turbines based on the type of energy at the inlet as either impulse turbines (only kinetic energy) or reaction turbines (both pressure and kinetic energy). It describes the Pelton wheel and Francis turbine as examples of each type. It further classifies turbines based on the main flow direction and provides ranges for suitable head based on specific speed. In summary, the document provides an overview of common hydraulic turbine classifications and examples like the Pelton and Francis turbines used for high and medium heads respectively.
This document provides an introduction to heat transfer and thermodynamics concepts. It discusses how heat transfer is related to thermodynamics and distinguishes between different forms of energy. The three main modes of heat transfer are conduction, convection and radiation. Heat is defined as the transfer of energy between two systems due to a temperature difference, and will flow from the higher temperature object to the lower temperature one. The document provides objectives and outlines concepts like thermal energy, mechanisms of heat transfer, Fourier's law of conduction and applications of heat transfer.
This document provides information about a group project to design an impulse turbine. The group leader is Abdul Jabbar and the other 7 group members are listed. It then provides details about turbines in general and impulse turbines specifically. It discusses the classification, working principle, parts, and efficiency of impulse turbines. It also compares impulse turbines to reaction turbines and lists the advantages and disadvantages of impulse turbines.
Heat transfer from extended surfaces (or fins)tmuliya
This file contains slides on Heat Transfer from Extended Surfaces (FINS). The slides were prepared while teaching Heat Transfer course to the M.Tech. students in Mechanical Engineering Dept. of St. Joseph Engineering College, Vamanjoor, Mangalore, India.
Contents: Governing differential eqn – different boundary conditions – temp. distribution and heat transfer rate for: infinitely long fin, fin with insulated end, fin losing heat from its end, and fin with specified temperatures at its ends – performance of fins - ‘fin efficiency’ and ‘fin effectiveness’ – fins of non-uniform cross-section- thermal resistance and total surface efficiency of fins – estimation of error in temperature measurement - Problems
This document provides an overview of an experiment analyzing the performance of a mechanical draft cooling tower. The experiment varied the water flow rate and fan speed to measure water temperature changes. The Merkel equation was then used to calculate the "tower characteristic" or coefficient of performance. As the water to air flow rate ratio (LG) increased, the tower characteristic and efficiency decreased, matching the Merkel theory. The conclusion is that higher water flow rates decrease the cooling tower's efficiency and characteristic.
This document provides information about the Saybolt viscometer, a device used to measure the viscosity of fluids. It defines viscosity and describes how the Saybolt viscometer works by measuring the time it takes for a fixed volume of fluid to flow through a temperature-controlled orifice. The document discusses the advantages of accurate temperature control and direct viscosity comparisons, and the disadvantages of potential inaccuracies. It also notes the Saybolt viscometer is commonly used to test petroleum products and measure viscosities in the field.
Positive displacement pumps move fluids by trapping a fixed volume and forcing that volume from the suction to discharge side. Reciprocating pumps, like piston pumps, use reciprocating motion powered by engines while rotary pumps use rotating components like gears or lobes. Piston pumps have two check valves and a reciprocating piston powered by translating rotary motion into linear motion. They can be direct or indirect acting, simplex or duplex, and single or double acting. Diaphragm pumps use a flexible diaphragm instead of pistons. Rotary pumps have gears, lobes, screws, cams, or vanes that rotate to trap and move fluid and include gear, lobe, screw, vane, and cam pumps
This document discusses various types of pressure measurement. It defines pressure and units like pascals and atmospheres. Static pressure is exerted by stationary fluids while dynamic pressure results from moving fluids. Absolute pressure is measured against a vacuum and gauge pressure against atmospheric pressure. Hydrostatic pressure increases with depth in liquids. Common pressure measurement instruments include manometers, elastic elements like bourdon tubes, and electrical resistance gauges. Low pressures are measured using McLeod, Pirani, and ionization gauges. Selection depends on the pressure range, accuracy needed, and other factors like cost and maintenance.
This document summarizes Daniel Bernoulli and his theorem on fluid mechanics. It discusses how Bernoulli, a Swiss scientist born in the 1700s, discovered that an increase in the speed of a moving fluid is accompanied by a decrease in the fluid's pressure. Bernoulli's principle, also called Bernoulli's theorem, states that the total energy in a fluid remains constant provided the flow is steady, frictionless, and incompressible. The document then provides Bernoulli's equation and describes experiments using a Venturi meter to verify the theorem by measuring pressure and velocity changes at different pipe sections. It concludes that the experiments validate Bernoulli's equation and its applications in fluid mechanics and aerodynamics.
This document provides an overview of fluid pressure and measurement techniques. It begins with defining key concepts like hydrostatic pressure, Pascal's law, and pressure variation in static fluids. It then describes various devices used to measure pressure, including manometers (U-tube, single column, differential), and mechanical gauges (diaphragm, Bourdon tube, dead-weight, bellows). The document is divided into 5 units covering fluid statics, kinematics, dynamics, pipe flow, and dimensional analysis with the goal of teaching students to calculate pressure, hydrostatic forces, fluid flow, and losses in closed conduits.
Engineering applications of thermodynamicsNisarg Amin
The document discusses different thermodynamic cycles used in steam power plants, including Rankine, reheat, and regeneration cycles. It provides diagrams and equations to analyze each cycle. The Rankine cycle involves boiling water to steam, expanding the steam in a turbine, condensing it back to water, and pumping the water to high pressure. Both the reheat and regeneration cycles improve the Rankine cycle efficiency by adding additional heat transfer processes. The reheat cycle reheats steam after the high-pressure turbine, while regeneration uses feedwater heating to preheat water before boiling.
Refrigeration is the process of cooling a substance below the temperature of its surroundings. Major uses include air conditioning, food preservation, and industrial processes. A ton of refrigeration is the heat required to melt 1 ton of ice in 24 hours. The Carnot refrigeration cycle involves heat addition, heat rejection, and net work to transfer heat from a low temperature reservoir to a high temperature reservoir. The vapor compression cycle uses the same processes as the Carnot cycle and is commonly used in refrigeration systems. It involves compression, condensation, expansion, and evaporation. Refrigerants are circulated through the system's main components: compressor, condenser, expansion valve, and evaporator. Multi-pressure and cascade systems
The document discusses high pressure boilers used in thermal power plants. It describes the Rankine cycle used to generate electricity from heat energy. In the Rankine cycle, water is pumped to high pressure, heated to become steam, expanded through a turbine to produce work, and condensed back into a liquid. The key components of a thermal power plant that use this cycle are boilers, steam turbines, condensers, and feed pumps. Several types of high pressure boilers are then outlined, including fire-tube, water-tube, Benson, Velox, and Loeffler boilers, explaining their unique designs and advantages over conventional boilers.
This document provides an overview of heat pipes, including their working principle and key components. A heat pipe is a device that transfers heat using a vaporization-condensation cycle with very high efficiency. It contains a container, working fluid, and wick structure. As heat is applied at the evaporator end, the fluid vaporizes and moves through the container to the condenser end where it condenses and is pumped back to the evaporator by the wick, transferring heat in the process. Common working fluids, wick designs, and applications of heat pipes are discussed. Heat pipes can be used to efficiently transfer heat in electronics, aerospace, and other industrial applications.
Forced cooling of a supercritical steam turbine after shut down of power plantSrikar Yadav
Forced cooling of a supercritical steam turbine after a shut down of power plant- types of cooling system, detailed analysis of cooling system under practical experience of experts in specified field.
The document discusses the history and principles of vapor absorption refrigeration systems. Some key points:
- Vapor absorption was first discovered in 1824 by Michael Faraday and the first machine was built in 1860. It uses a refrigerant (ammonia) that is absorbed into a solvent (water) for compression.
- Unlike vapor compression, it uses heat rather than mechanical energy to change the refrigerant's state. This allows it to be powered by waste heat or solar energy.
- The first domestic refrigerator using this technology was invented in 1925 and used ammonia, hydrogen, and water in a "three-fluid" system to eliminate the need for a pump.
This document discusses impulse turbines, specifically the Pelton wheel turbine. It begins by defining a turbine as a machine that converts kinetic energy of a fluid into mechanical rotation. It then classifies turbines based on the type of energy at the inlet, direction of fluid flow, head of water, and specific speed. It describes impulse turbines as converting hydraulic energy to kinetic energy via efficient nozzles, and reaction turbines changing the pressure of fluid. The document focuses on Pelton wheel turbines, describing its components like the penstock, spear nozzle, casing, runner buckets. It discusses design factors like number of buckets and jet ratio. It concludes by defining types of power and efficiencies in impulse turbines.
1. Force can be measured using several principles including balancing against gravitational force, translating to fluid pressure, applying to an elastic member, or applying to a known mass and measuring acceleration.
2. Scales and balances measure force by balancing the unknown force against a known gravitational force on a standard mass. Multi-lever scales use a system of levers and counterweights to indirectly measure the applied force.
3. Elastic force meters like proving rings, beams, and springs measure the deflection or strain caused by an applied force. The deflection or strain is then related to the magnitude of the applied force.
Simple description about gas turbine. Where you are going to know about its classification,advantages and disadvantages also.Here also you can find-out where it is actually usages.
Governing of the Turbine | Fluid MechanicsSatish Taji
Watch Video of this presentation on Link: https://youtu.be/LmJtNo-zgjo
For notes/articles, Visit my blog (link is given below).
For Video, Visit our YouTube Channel (link is given below).
Any Suggestions/doubts/reactions, please leave in the comment box.
Follow Us on
YouTube: https://www.youtube.com/channel/UCVPftVoKZoIxVH_gh09bMkw/
Blog: https://e-gyaankosh.blogspot.com/
Facebook: https://www.facebook.com/egyaankosh/
This document provides an overview of different types of heat exchangers. It begins with an introduction to heat exchangers and their basic functions. It then describes several common types of heat exchangers including recuperators, regenerators, plate heat exchangers, shell and tube heat exchangers, and fin tube heat exchangers. It also discusses potential problems with heat exchangers such as fouling and corrosion and provides some precautions and considerations for heat exchanger design and cost.
This document discusses thermal expansion, which is the change in dimensions of materials due to changes in temperature. It defines linear expansion as the expansion in length and volume expansion as expansion in overall volume. The key factors that affect thermal expansion are the temperature change, material type, and original dimensions. Common materials and their coefficients of thermal expansion are provided. Examples of applications like loosening tight jar lids are given. Finally, several problems involving calculating dimensional changes due to temperature changes are presented.
This document discusses five learning outcomes related to electrical heating: 1) heat and temperature, heat capacity and heat transfer, 2) methods for controlling heating in different situations, 3) processes and techniques for water, space, and industrial heating, 4) AS3000:2007 wiring rules requirements, and 5) potential causes of malfunction in electric heating equipment and tests for diagnosing faults.
The document discusses the zeroth law of thermodynamics and temperature measurement. It can be summarized as follows:
1) The zeroth law states that if two bodies (A and B) are each in thermal equilibrium with a third body (C), then A and B are also in thermal equilibrium with each other. This establishes the transitive property of temperature.
2) Temperature is measured using thermometers that relate a physical property's change (like mercury expansion) to temperature. Common temperature scales are Celsius, Fahrenheit and Kelvin.
3) Various thermometer types are discussed, including liquid-in-glass, electrical resistance, thermocouple, and those using gas/vapor pressure changes
Heat transfer from extended surfaces (or fins)tmuliya
This file contains slides on Heat Transfer from Extended Surfaces (FINS). The slides were prepared while teaching Heat Transfer course to the M.Tech. students in Mechanical Engineering Dept. of St. Joseph Engineering College, Vamanjoor, Mangalore, India.
Contents: Governing differential eqn – different boundary conditions – temp. distribution and heat transfer rate for: infinitely long fin, fin with insulated end, fin losing heat from its end, and fin with specified temperatures at its ends – performance of fins - ‘fin efficiency’ and ‘fin effectiveness’ – fins of non-uniform cross-section- thermal resistance and total surface efficiency of fins – estimation of error in temperature measurement - Problems
This document provides an overview of an experiment analyzing the performance of a mechanical draft cooling tower. The experiment varied the water flow rate and fan speed to measure water temperature changes. The Merkel equation was then used to calculate the "tower characteristic" or coefficient of performance. As the water to air flow rate ratio (LG) increased, the tower characteristic and efficiency decreased, matching the Merkel theory. The conclusion is that higher water flow rates decrease the cooling tower's efficiency and characteristic.
This document provides information about the Saybolt viscometer, a device used to measure the viscosity of fluids. It defines viscosity and describes how the Saybolt viscometer works by measuring the time it takes for a fixed volume of fluid to flow through a temperature-controlled orifice. The document discusses the advantages of accurate temperature control and direct viscosity comparisons, and the disadvantages of potential inaccuracies. It also notes the Saybolt viscometer is commonly used to test petroleum products and measure viscosities in the field.
Positive displacement pumps move fluids by trapping a fixed volume and forcing that volume from the suction to discharge side. Reciprocating pumps, like piston pumps, use reciprocating motion powered by engines while rotary pumps use rotating components like gears or lobes. Piston pumps have two check valves and a reciprocating piston powered by translating rotary motion into linear motion. They can be direct or indirect acting, simplex or duplex, and single or double acting. Diaphragm pumps use a flexible diaphragm instead of pistons. Rotary pumps have gears, lobes, screws, cams, or vanes that rotate to trap and move fluid and include gear, lobe, screw, vane, and cam pumps
This document discusses various types of pressure measurement. It defines pressure and units like pascals and atmospheres. Static pressure is exerted by stationary fluids while dynamic pressure results from moving fluids. Absolute pressure is measured against a vacuum and gauge pressure against atmospheric pressure. Hydrostatic pressure increases with depth in liquids. Common pressure measurement instruments include manometers, elastic elements like bourdon tubes, and electrical resistance gauges. Low pressures are measured using McLeod, Pirani, and ionization gauges. Selection depends on the pressure range, accuracy needed, and other factors like cost and maintenance.
This document summarizes Daniel Bernoulli and his theorem on fluid mechanics. It discusses how Bernoulli, a Swiss scientist born in the 1700s, discovered that an increase in the speed of a moving fluid is accompanied by a decrease in the fluid's pressure. Bernoulli's principle, also called Bernoulli's theorem, states that the total energy in a fluid remains constant provided the flow is steady, frictionless, and incompressible. The document then provides Bernoulli's equation and describes experiments using a Venturi meter to verify the theorem by measuring pressure and velocity changes at different pipe sections. It concludes that the experiments validate Bernoulli's equation and its applications in fluid mechanics and aerodynamics.
This document provides an overview of fluid pressure and measurement techniques. It begins with defining key concepts like hydrostatic pressure, Pascal's law, and pressure variation in static fluids. It then describes various devices used to measure pressure, including manometers (U-tube, single column, differential), and mechanical gauges (diaphragm, Bourdon tube, dead-weight, bellows). The document is divided into 5 units covering fluid statics, kinematics, dynamics, pipe flow, and dimensional analysis with the goal of teaching students to calculate pressure, hydrostatic forces, fluid flow, and losses in closed conduits.
Engineering applications of thermodynamicsNisarg Amin
The document discusses different thermodynamic cycles used in steam power plants, including Rankine, reheat, and regeneration cycles. It provides diagrams and equations to analyze each cycle. The Rankine cycle involves boiling water to steam, expanding the steam in a turbine, condensing it back to water, and pumping the water to high pressure. Both the reheat and regeneration cycles improve the Rankine cycle efficiency by adding additional heat transfer processes. The reheat cycle reheats steam after the high-pressure turbine, while regeneration uses feedwater heating to preheat water before boiling.
Refrigeration is the process of cooling a substance below the temperature of its surroundings. Major uses include air conditioning, food preservation, and industrial processes. A ton of refrigeration is the heat required to melt 1 ton of ice in 24 hours. The Carnot refrigeration cycle involves heat addition, heat rejection, and net work to transfer heat from a low temperature reservoir to a high temperature reservoir. The vapor compression cycle uses the same processes as the Carnot cycle and is commonly used in refrigeration systems. It involves compression, condensation, expansion, and evaporation. Refrigerants are circulated through the system's main components: compressor, condenser, expansion valve, and evaporator. Multi-pressure and cascade systems
The document discusses high pressure boilers used in thermal power plants. It describes the Rankine cycle used to generate electricity from heat energy. In the Rankine cycle, water is pumped to high pressure, heated to become steam, expanded through a turbine to produce work, and condensed back into a liquid. The key components of a thermal power plant that use this cycle are boilers, steam turbines, condensers, and feed pumps. Several types of high pressure boilers are then outlined, including fire-tube, water-tube, Benson, Velox, and Loeffler boilers, explaining their unique designs and advantages over conventional boilers.
This document provides an overview of heat pipes, including their working principle and key components. A heat pipe is a device that transfers heat using a vaporization-condensation cycle with very high efficiency. It contains a container, working fluid, and wick structure. As heat is applied at the evaporator end, the fluid vaporizes and moves through the container to the condenser end where it condenses and is pumped back to the evaporator by the wick, transferring heat in the process. Common working fluids, wick designs, and applications of heat pipes are discussed. Heat pipes can be used to efficiently transfer heat in electronics, aerospace, and other industrial applications.
Forced cooling of a supercritical steam turbine after shut down of power plantSrikar Yadav
Forced cooling of a supercritical steam turbine after a shut down of power plant- types of cooling system, detailed analysis of cooling system under practical experience of experts in specified field.
The document discusses the history and principles of vapor absorption refrigeration systems. Some key points:
- Vapor absorption was first discovered in 1824 by Michael Faraday and the first machine was built in 1860. It uses a refrigerant (ammonia) that is absorbed into a solvent (water) for compression.
- Unlike vapor compression, it uses heat rather than mechanical energy to change the refrigerant's state. This allows it to be powered by waste heat or solar energy.
- The first domestic refrigerator using this technology was invented in 1925 and used ammonia, hydrogen, and water in a "three-fluid" system to eliminate the need for a pump.
This document discusses impulse turbines, specifically the Pelton wheel turbine. It begins by defining a turbine as a machine that converts kinetic energy of a fluid into mechanical rotation. It then classifies turbines based on the type of energy at the inlet, direction of fluid flow, head of water, and specific speed. It describes impulse turbines as converting hydraulic energy to kinetic energy via efficient nozzles, and reaction turbines changing the pressure of fluid. The document focuses on Pelton wheel turbines, describing its components like the penstock, spear nozzle, casing, runner buckets. It discusses design factors like number of buckets and jet ratio. It concludes by defining types of power and efficiencies in impulse turbines.
1. Force can be measured using several principles including balancing against gravitational force, translating to fluid pressure, applying to an elastic member, or applying to a known mass and measuring acceleration.
2. Scales and balances measure force by balancing the unknown force against a known gravitational force on a standard mass. Multi-lever scales use a system of levers and counterweights to indirectly measure the applied force.
3. Elastic force meters like proving rings, beams, and springs measure the deflection or strain caused by an applied force. The deflection or strain is then related to the magnitude of the applied force.
Simple description about gas turbine. Where you are going to know about its classification,advantages and disadvantages also.Here also you can find-out where it is actually usages.
Governing of the Turbine | Fluid MechanicsSatish Taji
Watch Video of this presentation on Link: https://youtu.be/LmJtNo-zgjo
For notes/articles, Visit my blog (link is given below).
For Video, Visit our YouTube Channel (link is given below).
Any Suggestions/doubts/reactions, please leave in the comment box.
Follow Us on
YouTube: https://www.youtube.com/channel/UCVPftVoKZoIxVH_gh09bMkw/
Blog: https://e-gyaankosh.blogspot.com/
Facebook: https://www.facebook.com/egyaankosh/
This document provides an overview of different types of heat exchangers. It begins with an introduction to heat exchangers and their basic functions. It then describes several common types of heat exchangers including recuperators, regenerators, plate heat exchangers, shell and tube heat exchangers, and fin tube heat exchangers. It also discusses potential problems with heat exchangers such as fouling and corrosion and provides some precautions and considerations for heat exchanger design and cost.
This document discusses thermal expansion, which is the change in dimensions of materials due to changes in temperature. It defines linear expansion as the expansion in length and volume expansion as expansion in overall volume. The key factors that affect thermal expansion are the temperature change, material type, and original dimensions. Common materials and their coefficients of thermal expansion are provided. Examples of applications like loosening tight jar lids are given. Finally, several problems involving calculating dimensional changes due to temperature changes are presented.
This document discusses five learning outcomes related to electrical heating: 1) heat and temperature, heat capacity and heat transfer, 2) methods for controlling heating in different situations, 3) processes and techniques for water, space, and industrial heating, 4) AS3000:2007 wiring rules requirements, and 5) potential causes of malfunction in electric heating equipment and tests for diagnosing faults.
The document discusses the zeroth law of thermodynamics and temperature measurement. It can be summarized as follows:
1) The zeroth law states that if two bodies (A and B) are each in thermal equilibrium with a third body (C), then A and B are also in thermal equilibrium with each other. This establishes the transitive property of temperature.
2) Temperature is measured using thermometers that relate a physical property's change (like mercury expansion) to temperature. Common temperature scales are Celsius, Fahrenheit and Kelvin.
3) Various thermometer types are discussed, including liquid-in-glass, electrical resistance, thermocouple, and those using gas/vapor pressure changes
In this presentation we have discussed about temperature measuring instruments used in industry. Like Mechanical , electrical and non contact types instruments for measuring temperature
This presentation summarizes different temperature measurement devices. It discusses common thermometers like liquid-in-glass, bimetallic, and pressure spring thermometers. It also covers thermocouples, which measure temperature based on the thermoelectric effect between two dissimilar metals. Resistance thermometers are described as measuring temperature through changes in electrical resistance. Finally, pyrometers are summarized as non-contact devices that measure the infrared radiation emitted from an object to determine its temperature.
This document discusses temperature measurement and various instruments used for measuring temperature. It describes that temperature is the mean kinetic energy of molecules and is the driving force causing heat transfer. Common temperature measurement instruments include thermometers, pyrometers, and instruments that measure changes in physical properties like pressure, electrical resistance, and radiation intensity with temperature. Liquid-in-glass and bimetallic thermometers are described as examples of instruments that measure changes in physical dimensions with temperature.
This document provides an overview of various temperature measurement techniques. It discusses liquid-in-glass thermometers, bimetallic strip thermometers, thermocouples, resistance temperature detectors (RTDs), thermistors, and pyrometers. For each technique, it describes the working principle, advantages, and disadvantages. The document is intended to teach students in an ELET 241 process instrumentation course about common methods for temperature measurement.
This document provides an overview of industrial temperature measurement. It discusses different temperature scales and units used in engineering. Common temperature measurement devices are described, including liquid-in-glass thermometers, bimetallic thermometers, resistance temperature detectors (RTDs), and thermocouples. RTDs and thermocouples are electrical sensors that change resistance or voltage, respectively, with temperature. Each device type has advantages and limitations for different applications and temperature ranges. Proper setup and wiring is important to reduce measurement errors from reference junctions or lead wire resistances.
Thermal physics discusses kinetic molecular theory and Brownian motion. Heat is defined as the flow of energy from a warm object to a cooler object. Heat energy is the result of atomic/molecular movement in solids, liquids and gases. Temperature is a measure of heat energy, with higher temperatures indicating faster particle movement. Thermometers measure temperature using various methods like liquid expansion. Thermal conduction transfers heat through particle collisions, while convection transfers heat through fluid movement. Radiation transfers heat as electromagnetic waves. The greenhouse effect occurs naturally but is enhanced by human emissions, contributing to global warming.
The document discusses various methods for measuring temperature, including primary reference temperatures defined by the International Practical Temperature Scale. It describes mechanical methods like liquid-in-glass thermometers, electrical methods using resistance temperature detectors and thermistors, and thermoelectric sensors like thermocouples. Specifically, it provides details on how bimetallic strips, pressure thermometers, RTDs, thermistors, and thermocouples measure temperature based on physical properties like expansion, resistance, or thermoelectric effects.
This document discusses different methods of electrical temperature measurement. It describes thermocouples, which generate an electrical signal based on the thermoelectric effect produced by junctions of two different metals. Resistance temperature detectors are also covered, which measure temperature by relating the change in electrical resistance of metals like platinum to temperature variations. Thermistors are semiconductors with resistance that decreases with rising temperature. The document provides details on the construction, working principles, advantages and disadvantages of each type of electrical temperature measuring instrument.
Temperature is a measure of the average kinetic energy of particles in a body. It determines whether a body is in thermal equilibrium with others. Temperature is measured using various devices like liquid-in-glass thermometers, thermistors, thermocouples, and resistance temperature detectors (RTDs). These devices use different principles like thermal expansion of liquids, variation of electrical resistance with temperature, and Seebeck and Peltier effects to measure temperature. Common temperature scales include Celsius, Fahrenheit, Kelvin and Rankine, which are related through defined formulas.
1. Temperature is a measure of the average kinetic energy of particles in a sample of matter. Thermometers are devices used to define and measure temperature.
2. Thermometers work by exploiting a physical property, like length or resistance, that changes uniformly with temperature. They require fixed points like freezing and boiling points to define a temperature scale.
3. Common thermometers include liquid-in-glass, bimetallic, resistance, and thermoelectric types. Each exploits a different temperature-sensitive physical property and has advantages like accuracy, range, or response time.
Thermometry is the science of temperature measurement. There are various types of thermometers that use different principles:
1. Liquid-in-glass thermometers use thermal expansion of liquids like mercury.
2. Bimetallic thermometers use the different coefficients of thermal expansion in two metals bonded together.
3. Resistance temperature detectors (RTDs) measure the change in electrical resistance of metals with temperature. Platinum RTDs are commonly used.
4. Thermocouples generate small voltages from the Seebeck effect created by junctions of two different metals and allow temperature measurements over a wide range.
This document discusses temperature measurement and different temperature indicators. It provides information on various temperature scales, conversion between scales, and the two main types of temperature indicators: filled bulb and bimetallic strip. It also discusses temperature transmitters such as RTDs, thermocouples, and thermistors, describing their operation, advantages, disadvantages, and appropriate applications. Special consideration is given to proper sensor installation using thermowells to protect sensors from process conditions.
The document discusses different methods of temperature measurement. It describes four major temperature scales - Fahrenheit, Celsius, Kelvin and Rankine scales. It then discusses various temperature measurement transducers including vapour pressure thermometers, bimetallic thermometers, thermistors, resistance temperature detectors (RTDs), and thermocouples. For each transducer, it provides details on their working principles, types, advantages and applications. The document is a comprehensive overview of industrial temperature measurement techniques.
The document discusses different methods of temperature measurement. It describes four major temperature scales - Fahrenheit, Celsius, Kelvin and Rankine. It then discusses different temperature transducers including vapour pressure thermometers, bimetallic thermometers, thermistors, resistance temperature detectors (RTDs), and thermocouples. Vapour pressure thermometers use the expansion of a volatile liquid to measure temperature, while bimetallic thermometers use the differential expansion of two metals bonded together. Thermistors are semiconductors whose resistance changes with temperature, while RTDs use platinum resistance changes to measure temperature. Thermocouples generate a voltage related to temperature from the junction of two different metals.
This document discusses different types of thermometers and how they work. It describes liquid thermometers like mercury and alcohol thermometers which use the property of thermal expansion. Gas thermometers measure the pressure of a confined gas. Resistance thermometers use platinum coils and its changing resistance. Thermoelectric thermometers utilize the Seebeck effect to convert temperature differences into electrical signals. Thermocouples and thermopiles are discussed as types of thermoelectric thermometers.
This document discusses various methods of industrial temperature measurement. It describes common temperature sensors such as liquid-in-glass thermometers, bimetallic thermometers, thermocouples, resistance temperature detectors (RTDs), and radiation/infrared thermometers. For each sensor, the document outlines the basic measurement principle, advantages, disadvantages, typical temperature ranges, and other specifications. It also discusses related topics such as temperature scales, reference junction compensation, sensor installation considerations, and change-of-state indicators.
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2. • Temperature can be defined as
a) The condition of a body which
determines the transfer of heat to or
from other bodies.
b) The degree of hotness or coldness
as referenced to a specific scale of
temperature measurement.
3. HEAT
Energy that flows to a body and causes it to increase its
temperature, melt, boil, expand, or undergo other
changes is called heat.
Unit of heat is BTU (British thermal unit). The amount of
thermal energy required to raise the temperature of 1 lb
of water 1 degree F at atmospheric pressure.
1 BTU = 1055 joules.
Calorie
The amount of heat needed to raise the temperature of
one gram of water 1 deg C (starting at 15 deg C) at
atmospheric pressure. 1 Cal = 4.184 joule.
4. Specific heat
It is defined as the ratio of heat required to raise the
temperature of a certain weight of a substance 1o
F to
that required to raise the temperature of the same
weight of water 1o
F (measured under constant
pressure).
Vaporization
The change of physical state from liquid to gas is called
vaporization.
Condensation
The change of physical state from gas to liquid is called
condensation.
5. Latent heat of vaporization
The amount of heat necessary to change a substance
at the boiling point from liquid to gas is called latent heat
of vaporization.
Fusion
The change of physical state from liquid to solid is
called fusion ( or freezing).
Melting
The change of physical state from solid to liquid is
called melting.
Latent heat of fusion:
The amount of heat that must be removed as a
substance changes from a liquid to a solid , or added as
the solid becomes liquid is referred to as the latent heat
of fusion.
6. Temperature scales
Celsius: Melting point of ice is 0 and boiling point is 100.
o
C = (o
F – 32) / 1.8.
Fahrenheit: Melting point of ice is 32 and boiling point is 212.
o
F=(1.8 * o
C ) + 32.
Kelvin It is absolute scale.
K= o
C +273.15.
Rankine
o
R = o
F +459.67
Absolute zero
A hypothetical temperature at which a substance would have no
thermal energy. T (abs.) = -273.15 o
C
Triple point
The temperature at which gaseous, liquid, and solid states of a
substance exist simultaneously.
7.
8. All temperature measurements in industry are of two
basic groups.
A). Non Electric type
Bimetallic, Liquid in glass, Filled thermal system.
B). Electric type
Thermocouple, RTD, Thermistor, Pyrometer (Radiation & Optical)
Temperature is indicated by the changes it causes in
certain instruments.
• Changes in density ( liquid in glass thermometers)
• Changes in length or volume (bimetallic or filled system)
• Voltage generated at junction of dissimilar metals
(thermocouple)
• Resonant frequency of crystals (quartz thermometers)
• Changes in electrical resistance (Resistance
thermometers)
9.
10. BIMETALLIC THERMOMETERS
Coefficient of thermal expansion
• It is the change in length or volume of a substance per
degree of temperature change.
• Bimetallic thermometers use the difference in thermal
expansion of two different metals to indicate
temperature. Two straight metal strips are placed side by
side and welded together lengthwise. Bimetallic strip
bends towards the side that has the lower rate of thermal
expansion.
• If one end of strip is fixed , the distance the other end
bends is directly proportional to the square of the length
of the metal strip, as well as to the total change in
temperature, while inversely proportional to the thickness
of the metal. Invar (alloy of iron and nickel) is used as
low expansion material while brass (alloy of copper and
zinc) is used as high expansion material.
• Bimetallic thermometers are available in ranges from -75 o
C to 540
o
C with accuracy of ±1%.
11.
12. LIQUID IN GLASS THERMOMETERS
• Its operation is based on the principle that liquids
expand as temperature increases. It consists of a
small bore glass tube with a thin wall glass tube at
its lower end. Liquid filled is usually mercury or an
organic compound.
13.
14. FILLED THERMAL SYSTEMS
• The basic components of a
filled system thermometer are
• Thermometer bulb
• Capillary tube
• Bourdon tube
• The entire system is filled with
filling fluid. A change in
temperature causes the fluid to
expand or contract, in turn
causing the bourdon tube to
move.
15. 1. Liquid filled system
A bulb is inserted into the substance to be measured. Filling liquid inside the
bulb (commonly toluene or xylene) is heated or cooled until the temperature of
the filling liquid matches the temperature of the measured substance. Mercury
is also used as filling fluid due to rapid response to temperature changes.
2. Gas filled systems
It operates on the principle that the pressure of a confined gas varies directly
with its absolute temperature.
P=kT, where k=constant, and T=absolute temperature.
Nitrogen gas is normally used as filled gas.
3. Vapor pressure systems
Liquid in vapor pressure system vaporizes during operation. Bulb is partially
filled with liquid while capillary and bourdon are filled with vapor. Liquids used
are methyl chloride, sulfur dioxide, ether alcohol, and toluene.
A gas remains gaseous under pressure at normal room temperature, but a
vapor under pressure at normal room temperature returns to its liquid or solid
state.
16. Thermometer bulbs
• It is usually made of stainless
steel due to good heat transfer
properties.
• Plain bulb: Not used where
rapid response is important.
• Averaging bulb: provides
rapid response to temperature
changes.
• Capillary bulb:
• It is wound in helix, increasing
surface area and improving
response time.
17. Capillary tube
A capillary should contain the smallest possible volume of filling fluid. Change
of temperature in liquid in capillary can cause movement of bourdon tube.
Bourdon tubes
Helical bourdon tube is commonly used. Bourdon tube uncoils due to
temperature rise in system. An attached linkage is used to indicate system
temperature.
A transducer is used to convert position of bourdon tube to an electric or
pneumatic signal for remote transmission.
Advantages
Filled system thermometers are used with accuracy of ±0.5%. Their
advantages are lesser maintenance, no electric power requirement, satisfactory
time response and accuracy.
Disadvantage
The disadvantage is that the entire system usually must be replaced in case of
failure.
18. RESISTANCE TEMPERATURE DETECTOR
• It works on the principle that electrical resistance of any
material increases with temperature increase and vice
versa. A piece of nickel or platinum wire can be used to
measure resistance for different temperatures.
• RTD resistance elements are constructed of platinum,
copper or nickel. The metal should have a high
coefficient of resistance (change in resistance that
occurs with a change in temperature).
• A platinum RTD is normally used to measure precise
temperature from -259 to 631 o
C.
• Pt 100 means temperature is 0 o
C at 100 ohms
resistance.
19. Measurement of unknown resistance
• The electrical circuit used for
temperature measurement is a
Wheatstone bridge. The bridge
converts the RTD’s change in
resistance to a voltage output.
This circuit uses four separate
electrical resistors, one of
which is the RTD.
• The bridge is initially balanced,
with voltage output equal to
zero, because all four resistors
are equal. If the resistance of
the RTD changes, due to a
temperature change, the
bridge becomes unbalanced,
resulting in a voltage output
other than zero.
20. • In two conductors RTD, these conductors
become part of resistance being measured, so
ambient temperature variation will result in error
of net temperature.
21. • Three conductor RTD cable is mostly used to minimize the effect of ambient temperature
variations on cable.
• In three lead circuit, L1 and L2 are in opposite arms of the bridge. The change in L1 is equal to
L2. Because L3 is in series with the input voltage, the bridge output voltage is unaffected.
• Four conductor RTD is used to reduce temperature effects on cable. This circuit is used in a
system with long lead wires whose temperature varies greatly during measurement.
22. • Resistance elements are usually
long spring like wires enclosed in a
metal sheath. The platinum element
is surrounded by a porcelain
insulating material that prevents a
short circuit from developing
between the wire and the sheath.
The sheath is made of Inconel, an
alloy of nickel, iron, and chromium.
This material has excellent corrosion
resistance and can be used in
extremely harsh environments for
long periods of time without
deteriorating.
• The thermowell protects the RTD
from any contamination or corrosion
caused by the gases or liquids being
measured.
• A heavy metal head, made of cast
iron or aluminum, covers the
terminal block containing the
electrical connections between the
RTD and Wheatstone bridge.
• The main advantage of RTD is
stability , linearity and accuracy.
23. THERMISTOR
• Its name is derived from thermally sensitive resistor. Resistance of a
thermistor varies as a function of temperature. Thermistor is an
electrical device made of solid semiconductor with high temperature
coefficient of resistivity.
• It is usually made of complex metal oxides (manganese-nickel,
manganese – nickel –iron).
• In negative coefficient thermistor resistance decreases as
temperature increases.
• A positive coefficient thermistor (resistance increases as temp.
increases) is connected in series with a control relay to react to
temperature limits or overload conditions. As temperature increases
the resistance of thermistor increases. This causes current in the
relay coil to decrease, and relay trips out. It is used to protect
industrial motors.
• Thermistor is very sensitive so it often does not require wheat stone
bridge.
• They are used in range of -260 to 315 o
C.
24. THERMOCOUPLE
• It works on the principle that if two wires made of different metals are joined
at one end and joined ends are at different temperatures than the open
ends, a small voltage is produced across the open ends. Joined ends are
called hot junction while open ends are called cold junction.
• To keep the wires apart, porcelain insulator is used for higher temperature.
• For accurate temperature measurement, reference junction temperature
must remain constant. Indicating or recording instruments use internal and
automatic cold junction compensation. Either a thermistor directly measures
mV in junction box and is compensated for net temperature output or a
thermocouple added to actual thermocouple can give net temperature.
25. Two main classes of thermocouples are
Noble metal thermocouples: platinum or gold is used as one wire. Highly resistant to
corrosion, low electric resistivity, good repeatability. Type S,R and B are all noble metal
thermocouples.
Base metal thermocouples: type J, T, E, and K are all base metal thermocouples.
Thermal emf developed is dependant on metals of thermocouple. Common types of
thermocouples are as follows.
A). COPPER-CONSTANTAN (T TYPE)
Copper element used as positive conductor and constantan element for negative
conductor. Constantan contains 55% copper and 45% Nickel. This thermocouple is used
in Oxidizing or reducing atmosphere.
Range: -300 o
F to +600 o
F
B). IRON – CONSTANTAN (J TYPE)
Iron element is used as positive conductor and constantan element for negative
conductor. This thermocouple is used in Oxidizing or reducing atmosphere.
Range: -100 o
F to +1500 o
F
C). CHROMEL- ALUMEL (K TYPE)
Chromium alloy is used as positive conductor and Alumel element for negative
conductor. This thermocouple is used in Oxidizing atmosphere.
Range: -300 o
F to +1600 o
F
26. D). CHROMEL-CONSTANTAN (E TYPE)
• This thermocouple is used in Oxidizing
atmosphere.
• Chromel = 90% Nickel & Chromium = 9%
• Constantan = 44% Nickel & Cupper = 55%
• Range: +32 o
F to +1600 o
F
E). PLATINUM RHODIUM/PLATINUM
(R ,B, S TYPE)
• This thermocouple is used in Oxidizing
atmosphere.
• In R type thermo couple, pt = 87% & Rh =
13%
• Range: Up to +2700 o
F
• In S type thermo couple, pt = 90% & Rh =
10%
• Range: 0 o
F to +2100 o
F
• In B type thermo couple, pt = 70% & Rh =
30%
• Range: 1472 o
F to +3092 o
F
27.
28. • An extension wire made of the same material as the thermocouple
is referred to as thermocouple wire, but a wire made of different
material (with characteristics similar to the thermocouple’s) is
referred to as compensating lead wire. thermocouple wire can be
used for type T and J because material is not expensive.
Compensating lead wire is normally made of copper or
copper/nickel alloy.
29. SPECIAL PURPOSE THERMOCOUPLES
HOT BLAST
• It has fast response. It is used to measure temperature of preheated air to furnace.
GASKET THERMOCOUPLE
• It is mounted on studs or bolts to measure skin temperature of process lines, shell vessels or other process
machinery.
TUBE WALL THERMOCOUPLE
• It is used to measure furnace tube temperature. It is installed by welding pad to tube or other surface.
SPECIAL FEATURES OF THERMOCOUPLES
• 1). THERMOPILE
• Thermocouples connected in series to measure net voltage of thermocouples.
• 2). DIFFERENTIAL TEMPERATURE
• Two thermocouples can be used for measuring differential temperature between two points.
Connections are made in such a way that emf’s developed oppose each other. If temperature of
both thermocouples is equal , net emf is zero. It can be used to measure differential temperature
of top and bottom of steam line.
• 3). AVERAGE TEMPERATURE
• To measure average temperature across a vessel or duct, thermocouples may be used in parallel
connection. Net voltage produced at instrument is average voltage developed by thermocouples.
• For accurate measurement, resistance of all thermocouples and extension wires should be same.
Due to variation in temperature of thermocouple and length of extension wire, a swamping
resistor is used (1.5 Kilo ohm normally).
30. Pyrometry
• It is a method of measuring temperature without physical contact between the transducer and the
heated material. Its principle is based on relationship between temperature of a hot body and the
electromagnetic radiation it emits.
• Electromagnetic wave: A single burst of energy, like the one emitted by the solid, is referred to
as an electromagnetic wave.
• Electromagnetic radiation: A series of electromagnetic waves is referred to as electromagnetic
radiation.
• Pyrometry is based on the principle that intensity of electromagnetic radiation emitted by a body
depends partly on body’s emissivity or emittance and also depends on temperature of a body.
• Emissivity: the ability of a surface to send out radiant energy.
• Emittance: amount of energy emitted per unit area by a radiating surface.
• The radiation is not visible because it is in the infrared range of the electromagnetic spectrum,
and therefore is lower in frequency than visible light.
• Emittance varies inversely with reflection, so good emitters are poor reflectors but good
absorbers. Black body is an ideal emitter/absorber.
• Emittance = Test object’s total radiation / black body’s total radiation.
• Two bodies at same temperatures but with different values of emittance, radiate different
amounts of heat.
• Most bodies emit and absorb radiation at specific wavelengths. The wave length causes an
object to have a characteristic color if it is heated.
31. Types of pyrometers
Narrowband pyrometer (optical pyrometer)
• It operates on the principle of the relationship between the intensity
of emitted radiation and the temperature of the body. To measure
the temperature of a body the intensity (brightness) of radiation
emitted by body is matched to brightness of a reference object
whose temperature is known. It works in portion of electromagnetic
spectrum that lies in visible light range (0.35 to 0.75 µ).
Broadband pyrometers (radiation pyrometers)
It is based on relationship between total emitted radiation and
temperature. It works in all range of electromagnetic spectrum but
likely in visible and infrared light range. As the total energy radiated
by a hot body enters the pyrometer, it is focused by the lens onto
the detector (thermopile, photocell, thermistor or RTD). Suppose the
detector measures temperature 80 o
C for 1200 o
C temperature of
target, then increase in targets temperature causes increase in
detectors temp.
32.
33. Types of narrow band pyrometers
Manual optical pyrometer
Its use is limited to the wavelengths to which the human eye can respond.
Reference filament is heated by an electric current, which can be varied by a
control knob. Brightness of filament is matched to that of target object. When
they are perfectly matched, filament disappears and can’t be seen. Control knob
is scaled to read directly in degrees Celsius or Fahrenheit. Filter limits (allows)
the portion of electromagnetic spectrum visible to human eye. Its advantage is
flexibility and portability. It cannot measure temperature below 800 o
C because
level of radiation emitted is too low.
34. Automatic optical pyrometer
• It compares the intensity of energy radiated by a target to that emitted by a
controlled reference (filament). The modulator passes the radiation, first from target
then from the reference through to the filter. Filter passes radiation of selected
wavelength to detector. Detector (photomultiplier tube or solid state photo
detectors) senses radiations alternately and generates an electrical signal
proportional to the intensity of the radiation. Controller receives signal from detector
and varies intensity of filament radiation until both intensities matched. The current
through filament is measure of target’s temperature.
35. Primary and secondary standards
• There are three standard industrial temperature-measuring instruments.
• platinum resistance thermometer
• platinum rhodium-platinum thermocouple
• Infrared optical pyrometer.
• These instruments are periodically calibrated from National Institute of
Standards and Technology (NIST). NIST used to be called the National
Bureau of Standards (NBS).
Primary calibration standards
• The international practical temperature scale (IPTS) is based on 11
temperatures at which specific substances change their state. These
temperature points are primary fixed points. These points were chosen
because the specific conditions and corresponding temperatures can be
easily duplicated.
• Secondary fixed points provide additional data points in the middle portion of
the IPTS. These points are often used for testing and calibration of
temperature measuring instruments because they are more conveniently
obtained.
36. Primary fixed points for the IPTS
SUBSTANCE (STATE) TEMPERATURE (oc)
Hydrogen (triple point) (-) 259.34
Hydrogen /liquid/gas
equilibrium at 25/76
standard atmospheres)
(-) 256.108
Hydrogen (boiling point) (-) 252.87
Neon (boiling point) (-) 246.048
Oxygen (triple point) (-) 218.789
Oxygen (boiling point) (-) 182.962
Water (triple point) (+) 0.01
Water (boiling point) (+) 100
Zinc (freezing point) (+) 419.58
Silver (freezing point) (+) 961.93
Gold (freezing point) (+) 1064.43
38. Primary standard instruments
A primary standard is an instrument that meets specifications based on legal
international definitions of a fundamental unit of measurement. a Pt100 is the standard
for the temperature range of -259.34 to 630.74 o
C (the triple point of hydrogen to the
freezing point of antimony). A platinum/10% rhodium-platinum thermocouple (Type S) is
the standard from 630.74 to 1064.43 o
C (the freezing point of antimony to the freezing
point of gold). An optical pyrometer is the standard above 1064 o
C.
Secondary standard instruments
These are calibrated against primary standards and are nearly as accurate. These are
less expensive and easy to use than primary standards.
Working standard instruments
These are calibrated from secondary standards and are used for on-the-job testing and
calibration in the field.