Adjustable Dial thermometer WIKA model  S55

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Adjustable Dial thermometer WIKA model  S55

Adjustable Dial thermometer work on the bimetal, expansion or gas actuation principle. This enables scale ranges of -200 to +700 °C in different class accuracies, response times and resilience to environmental influences. Diverse connection designs, stem diameters, and individual stem lengths enable a flexible measuring point design. All thermometers are suited for operation in a thermowell if necessary.

What is Bimetallic Thermometer

The bimetallic thermometer consists of a bimetallic strip. A bimetallic strip is made of two thin metals which have different coefficients of expansion. The two metal strips are joined together by brazing, welding or riveting so that the relative motion between them is arrested. The bimetallic strip is in the form of a cantilever beam. An increase in temperature will result in the deflection of the free end of the strip  This deflection is linear and can be related to temperature changes. The radius of the curvature of the bimetallic strip which was initially flat is determined using the following relationship.

Model S50 WIKA thermometer

The model 55 bimetal thermometer has been developed and is manufactured in accordance with the EN 13190 standard. The high-quality thermometer has been designed especially for the requirements of the process industry. The temperature measuring instrument completely manufactured from stainless steel. The model 55 satisfies the high requirements for resistance against aggressive media. As an option, the case, the stem, and the process connection can be made from 316Ti (1.4571) to fulfil the highest requirements.

To allow optimum fitting to the process, individual insertion lengths and different process connections can be selected. When it comes to harsh climatic conditions at the place of use, model 55 is the right choice. It can be used at temperatures ranging from -40 °C to +70 °C (optional also up to -50 °C or -70 °C).

Applications

  • General process instrumentation in the
  • chemical and petrochemical industries
  • oil and gas industries
  • energy and water/wastewater industries
  • Temperature measurement in harsh and aggressive environments

Technical Features

the scale ranges

  • from -70 … +600 °C

Measuring element

  • Bimetal coil

Nominal size in mm

  • 100
  • 160

Connection designs

  •  S: Standard (male threaded connection)
  • 1: Plain stem (without thread)
  • 2: Male nut
  • 3: Union Nut
  • 4: Compression fitting (sliding on the stem)
  • 5: Union nut and loose threaded connection

Model

Model S5550

Back mount, adjustable stem, and dial

  • Dial: 100mm

Model S5551

Back mount, adjustable stem, and dial

  • Dial: 160mm

Material

The case, bayonet ring

  •  Stainless steel 1.4301 (304)

Stem, process connection

  • Stainless steel 1.4571 (316Ti)

Dial

  • Aluminium white, black lettering

Window

  • Instrument glass

Zero adjustment

  • on the case back side, external only for adjustable stem and dial (option)

Insertion length

  • L1 63 … 1,000 mm

minimum/maximum length is dependent on the measuring range and diameter

Temperature limits for storage and transport

  • -50 … +70 °C

Permissible ambient temperature

  •  -40 … +70 °C (with/without filling liquid)

Permissible operating pressure at the stem

  •  max. 25 bar, static

Ingress protection

  • IP65 per IEC/EN 60529
Types of Industrial Thermometer

Types of Industrial Thermometer

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Types of Industrial Thermometer

Thermometers are devices that measure temperature or a temperature gradient using a variety of different principles. Temperature is simply the numerical measurement of hot and cold—which has great importance in a wide variety of applications.

Temperature affects our comfort, cooks our food and is critical to making many products upon which we rely. Given the extreme importance of temperature across so many aspects of modern life, thermometers are a familiar tool to us.

Temperature is the most commonly measured parameter in commercial and industrial settings. Industries as diverse as food processing, pharmaceuticals, cold storage, paper manufacturing, and others absolutely rely on process temperatures being within a certain range.

Though there are many temperature sensing options, thermometers provide an inexpensive, versatile and reliable choice.

Gas-actuated Thermometers

The Gas-actuated-thermometers are suitable for raw ambient conditions. A case, ring, and stem are made of stainless steel. With a liquid filling, the thermometers can be used at measuring points with high vibrations.

The thermometers with capillary facilitate separation of the display unit from the measuring point. The measuring system in the gas thermometers consists of the stem, capillary and Bourdon tube in a case.

The complete measuring system is filled with an inert gas under pressure. A temperature change causes the internal pressure in the stem to change. The deflection of the Bourdon tube thus caused is transmitted to the pointer by a movement.

A version with rotatable (360°) and turntable case (90°) allow the thermometers to be aligned as desired under all installation conditions. In conjunction with a corresponding thermowell, these thermometers can also be used with aggressive media or high process-pressures.

Gas-actuated Thermometers Application

  • Chemical and petrochemical industry
  • Process engineering
  • Food industry

Technical Data

Measuring ranges

-200 … 50 °C to 0 … 700°C

Mounting
  • With Capillary
  • Without Capillary

 

 

Bimetal Thermometer

Bimetal thermometers use two strips of different metals to convert temperature into mechanical displacement. The different metals, often steel and copper or steel and brass, are joined together throughout their length and will expand at different rates as they are heated.

The difference in the expansion will cause the strip to bend one way if heated or the other if cooled. This movement correlates to the actual temperature and moves an indicator along the scale. The metal strips can be lengthened for sensitivity and are often coiled for compactness.

Bimetal thermometers are inexpensive, simple, and durable. As purely mechanical devices, they display only the current temperature on their dial. They can be accurate to about 1% full span. They are often used in food and beverage preparation, process temperature measurement, wastewater treatment, boiler systems, and other places.

Bimetal Thermometer Application

  • chemical
  • petrochemical
  • oil and gas
  • energy
  • water/wastewater industries
Temperature Transmitter

Temperature Transmitter

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Temperature Transmitter

Temperature Transmitter converts the input signal from a wide range of sensors, such as resistance sensors and thermocouples, but in some cases also from potentiometers, into a standardized output signal (e.g. 0 … 10 V or 4 … 20 mA).

With digital temperature transmitters, the sensor type and the measuring span can be freely configured, along with many further options such as the error signalization or a measuring point identification.

Type Of Temperature Transmitter

There are many different types of Temperature Sensor available and all have different characteristics depending upon their actual application. A temperature sensor consists of two basic physical types:

Contact Temperature Sensor Types

These types of temperature sensor are required to be in physical contact with the object being sensed and use conduction to monitor changes in temperature. They can be used to detect solids, liquids or gases over a wide range of temperatures.

Non-contact Temperature Sensor Types

These types of temperature sensor use convection and radiation to monitor changes in temperature. They can be used to detect liquids and gases that emit radiant energy as heat rises and cold settles to the bottom in convection currents or detect the radiant energy being transmitted from an object in the form of infra-red radiation (the sun).

Temperature Sensor

Negative Temperature Coefficient (NTC) thermistor

A thermistor is a thermally sensitive resistor that exhibits a large, predictable, and precise change in resistance correlated to variations in temperature.

An NTC thermistor provides a very high resistance at low temperatures. As temperature increases, the resistance drops quickly. Because an NTC thermistor experiences such a large change in resistance per °C, small changes in temperature are reflected very fast and with high accuracy (0.05 to 1.5 °C).

Because of its exponential nature, the output of an NTC thermistor requires linearization. The effective operating range is -50 to 250 °C for glass encapsulated thermistors or 150°C for a standard.

Resistance Temperature Detector (RTD)

An RTD, also known as a resistance thermometer, measures temperature by correlating the resistance of the RTD element with temperature. An RTD consists of a film or, for greater accuracy, a wire wrapped around a ceramic or glass core.

The most accurate RTDs are made using platinum but lower-cost RTDs can be made from nickel or copper. However, nickle and copper are not as stable or repeatable. Platinum RTDs offer a fairly linear output that is highly accurate (0.1 to 1 °C) across -200 to 600 °C. While providing the greatest accuracy, RTDs also tend to be the most expensive of temperature sensors.

Thermocouple

This temperature sensor type consists of two wires of different metals connected at two points. The varying voltage between these two points reflects proportional changes in temperature.

Thermocouples are nonlinear, requiring conversion when used for temperature control and compensation, typically accomplished using a lookup table. Accuracy is low, from 0.5 °C to 5 °C.  However, they operate across the widest temperature range, from -200 °C to 1750 °C.

Semiconductor-based sensors

A semiconductor-based temperature sensor is placed on integrated circuits (ICs). These sensors are effectively two identical diodes with temperature-sensitive voltage vs current characteristics that can be used to monitor changes in temperature.

They offer a linear response but have the lowest accuracy of the basic sensor types at 1 °C to 5 °C. They also have the slowest responsiveness (5 s to 60 s) across the narrowest temperature range (-70 °C to 150 °C).

Application Of Temperature Transmitters

  • monitoring temperature of a remote process
  • drive equipment such as meters, data loggers, chart recorders, computers or controllers.

Advantages of temperature sensor

Thermocouple measures temperature in -200oC to +2500oC range, RTD measures in -200oC to +850oC range, thermistor measures in -100oC to +260oC range and IC sensors measures in -45oC to 150oC range.

(Advantages of thermocouple are): No external power required, simple and rugged in construction, cheaper, support for wider temperature range etc.

  • (Advantages of RTD are ): More stable, higher accuracy, more linearity compare to thermocouple
  • (Advantages of thermistor are): Higher output, faster in operation
  • (Advantages of IC sensor are): Highest output, cheaper, most linear than all types

Disadvantages of temperature sensor

  • (Disadvantages of thermocouple are): Non linearity, least stability, Low voltage, Reference is needed, least sensitivity etc.
  • (Disadvantages of RTD are ): Lower absolute resistance, expensive, current source needed, less rugged compare to thermocouples etc.
  • (Disadvantages of thermistor are): Nonlinearity, limited support for temperature range, current source needed, fragile, self heating etc.
  • (Disadvantages of IC sensor are): Power supply needed, slower in operation, self heating, limited configurations, temperature upto 150oC etc.
Flange

Flange

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Flange

The Flange is the second most used joining method after welding. Flanges are used when joints need dismantling. It Provides flexibility for maintenance.

Flange Connects the pipe with various equipment and valves. Breakup flanges are added in the pipeline system if regular maintenance is required during plant operation.

Flange Materials Specification

Dimensions from carbon steel and stainless steel flanges are defined in the ASME B16.5 standard. The material qualities for these flanges are defined in the ASTM standards.

These ASTM standards, define the specific manufacturing process of the material and determine the exact chemical composition of pipes, fittings, and flanges, through percentages of the permitted quantities of carbon, magnesium, nickel, etc., and are indicated by “Grade”.

For example, a carbon steel flange can be identified with Grade F9 or F11, a stainless-steel flange with Grade F316 or Grade F321 etc..
Below you will find as an example a table with chemical requirements for fittings ASTM A403 Grade WP304, WP304L, WP316L and a table with frequent Grades, arranged on pipe and pipe-components, which belong together as a group.

As you may be have noted, in the table below, ASTM A105 has no Grade. Sometimes ASTM A105N is described; “N” stands not for Grade, but for normalized.

Normalizing is a type of heat treatment, applicable to ferrous metals only. The purpose of normalizing is to remove the internal stresses induced by heat treating, casting, forming etc.

Carbon Steel Flanges

The Carbon Steel Flanges are available in various dimensions. Exhibiting the properties such as high strength, high toughness, excellent fatigue strength, superior chemical resistance and high stress-corrosion cracking resistance, these flanges are ideal for connecting various pipes and are significant while support is required for mechanical parts.

  • ASTM A105, ASTM A350 LF1, LF2 CL1/CL2, LF3 CL1/CL2
  • ASTM A694 F42, F46, F48, F50, F52, F56, F60, F65, F70

Stainless Steel Flange

Stainless Steel Flanges are corrosion resistant and have a wide variety of uses. We carry a variety of threaded flanges, weld neck flanges and slip-on flanges and of course, we can custom build stainless steel flanges to your specifications.

  • ASTM A182 F304/304L, F316/316L, F316H, F310, F321, F44 (UNS S31254)
  • ASTM A403 WP316/316L
  • ASTM A403 WP304/304L
  • ASTM A182 F304, F304L, F316, F316L, F321

316 / 316L

316/316L is the most commonly used austenitic stainless steel in the chemical process industry. The addition of molybdenum increases general corrosion resistance, improves chloride pitting resistance and strengthens the alloy in high-temperature service.

Through the controlled addition of nitrogen, it is common for 316/316L to meet the mechanical properties of 316 straight grade while maintaining a low carbon content.

Applications of flanges

Flanges are integral parts of many engineering and plumbing projects.

In many applications, engineers need to find a way to close off a chamber or cylinder in a very secure fashion, usually, because the substance inside must differ from the substance outside in composition or pressure.

They do this by fastening two pieces of metal or other material together with a circle of bolts on a lip. This “lip” is a flange.

Plumbing

You can connect two sections of metal piping by soldering or welding them together, but pipes connected in this way are very susceptible to bursting at high pressures.

A way of connecting two sections of pipe more securely is by having flanged ends that you can connect with bolts. This way, even if gases or liquids build up to high pressures inside the pipe, it will often hold with no problem.

Mechanics

In order to connect two sections of a large, enclosed area, it is often best to used flanges and bolts. An example of this is the connection between the engine and the transmission in an automobile.

In this case, both the engine and the transmission contain a number of moving parts that can easily get damaged if they get dust or other small objects inside of them. By connecting the outer casings of the engine and transmission in this way, engineers protect the inner workings of both.

Electronics

Flanges have a specific purpose in cameras and other electronic devices. Though flanges in such items do not usually have to sustain high pressures, they do have to hold tight so they can keep out harmful particles.

These flanges are usually found connecting two different materials, such as the glass of a lens and the rest of the body of the camera.

TYPES OF FLANGES

The most used flange types in Petro and chemical industry are:

  • Welding Neck Flange
  • Slip On Flange
  • Socket Weld Flange
  • Lap Joint Flange
  • Threaded Flange
  • Blind Flange

SPECIAL FLANGES

Except for the most used standard flanges, there are still a number of special flanges such as:

  • Orifice Flanges
  • Long Welding Neck Flanges
  • Weld flange / Nipoflange
  • Expander Flange
  • Reducing Flange

Weld-neck

Complete with a tapered hub, these flanges are recognizable and used in high-pressure environments. The flange is particularly useful under repeat bending conditions.

Slip-on

A flange which is slipped over the pipe and welded both inside and outside to increase strength and prevent leakage. A favorite for engineers compared to the weld-neck due to their lower cost.

Socket-weld

With a static strength equal to the Slip-on flange, the Socket-weld is connected with the pipe with 1 fillet weld on the outside of the flange. Due to corrosion issues, some processes do not allow this flange.

Lap-joint

Used in conjunction with a lap joint stub end, the flange is slipped over the pipe but not fastened, unlike the slip-on. Instead, the flange is held in place by the pressure transmitted to the gasket by the flange pressure against the back of the pipe lap.

Threaded

Used in special circumstances, the threaded flange can be attached to the pipe without being welded. These are usually positioned on pipes with a deep wall thickness, used to create the internal thread.

Blind

Manufactured without a bore, these flanges are used to blank off the end of piping, valves and pressure vessel openings. They are also most suitable for high pressure-temperature applications.

References:

https://hardhatengineer.com/types-flanges-used-piping/

http://www.wermac.org/flanges/flanges_pipe-connections_pipe-flanges.html

http://www.sunnysteel.com/flange-material.php

https://blog.miragemachines.com/6-of-the-most-common-flange-types-used-in-the-oil-and-gas-industry

Types of thermometer

Types of thermometer – post 1

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Types of thermometer

Thermometers design to measure temperatures in industrial and home systems. In this paper, we introduce the standard  Types of thermometer in the industry.

mercury thermometer

The mercury-in-glass or the mercury thermometer designed by physicist Daniel Gabriel Fahrenheit in Amsterdam (1714).

It consists of a bulb containing mercury attached to a glass tube of narrow diameter; the volume of mercury in the tube is much less than the volume in the bulb.

The volume of mercury changes slightly with temperature; the small change in volume drives the narrow mercury column a relatively long way up the tube. The space above the mercury can be filling with nitrogen gas or it may be at less than atmospheric pressure, a partial vacuum.

Alcohol Thermometer

The most common liquid used in common household thermometers used to be mercury, but because of that material’s toxicity, In summary, it replaced by alcohol or ethanol.

Also An alcohol thermometer is a small sealed tube made of glass that has a small hollow bulb on one end and a thin capillary opening running through the length of its center.

The bulb and connected capillary chamber filled partly with ethanol and partly with nitrogen and ethanol vapors.

Enough alcohol places in the bulb so that at normal room temperatures it will extend into the narrow column. Along the length of the column, the tube is graded with several marks showing the temperature of the liquid at certain volumes.

Beckmann Differential Thermometer

The Beckmann differential thermometer used for measuring small differences in temperature, having a readability of around 0.001°C.

This makes it useful for the determination of melting points, boiling points, and calorimetry. Today it is superseded by sensitive digital thermometers using thermocouples, thermistors, etc.

Bimetallic Thermometer

It’s made up of two different metals bonded together, which expand by different amounts as they heat up. As the temperature changes, the bimetallic strip curves more or less tightly (contracts or expands) and the pointer, attached to it, moves up or down the scale.

Galileo thermometer

A Galileo thermometer (or Galilean thermometer) is a thermometer made of a sealed glass cylinder containing a clear liquid and several glass vessels of varying density. As the temperature changes, the individual floats rise or fall in proportion to their respective density and the density of the surrounding liquid.

Galileo thermometer used because he discovered the principle on which this thermometer base—that the density of a liquid changes in proportion to its temperature.

Infrared Thermometer

On its most basic design, an infrared thermometer consists of a lens to focus the infrared (IR) energy on to a detector, which converts the energy to an electrical signal that can display in units of temperature after being compensated for ambient temperature variation.

This configuration facilitates temperature measurement from a distance without contact with the object to measure.

As such, the infrared thermometer is useful for measuring temperature under circumstances where thermocouples or other probe type sensors cannot be used or do not produce accurate data for a variety of reasons.

Some typical circumstances are where the object to measure is moving; where the object surround by an EM field, as in induction heating; where the object contain in a vacuum or other controlled atmosphere; or in applications where a fast response is required.

Liquid crystal thermometers

Thermochromic Liquid Crystals (LCs) can be highly temperature sensitive, change to many colors, and are more expensive than leuco dyes.

LCs start black below their temperature range, go through the colors of a rainbow, and back to black again above the temperature range. LCs are reversible in that they can use over and over again. The picture shows an example of a liquid crystal sheet in response to warming.

Popular liquid crystal applications include medical devices, forehead, aquarium and room thermometers, promotional pieces and advertising applications.

Additionally, functional devices such as a propane tank gas level indicator are achieving much notoriety.

Liquid crystal thermometer strips use for thermal mapping and other industrial applications where custom inexpensive temperature monitoring is warranted.

We offer a wide range of liquid crystal thermometers as stock products, but also offer literally thousands of custom products for your label.

Bimetallic Thermometer

Bimetallic Thermometer

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Bimetallic Thermometer

In this article, we will introduce a Bimetallic Thermometer and how it dose work,also we will talk about the temperature & its application.

At the another part of the article will talk about the advantage of the bimetal and its sensors.
At the end of the article we will recommend to how to choose them and which factors is essential to choose the bimetal thermometers.

Thermometers are devices that measure temperature or a temperature gradient using a variety of different principles. Temperature is simply the numerical measurement of hot and cold—which has great importance in a wide variety of applications.

Temperature affects our comfort, cooks our food and is critical to making many products upon which we rely.

Given the extreme importance of temperature across so many aspects of modern life, thermometers are a familiar tool to us.

A thermometer is an instrument designed to measure and indicate the temperature of a specific application or condition. A bimetallic dial thermometer, commonly known as a bimetal thermometer, is installed at the point of measurement and is usually read from that location.

What is bimetal?

A bimetallic sensor is something that is made from two different types of metal joined together. Unlike many objects, bimetallic items are not made from a mixture of metals, but consist of layers of different metals.

Bi-metal is used for a variety of different reasons. Sometimes cheaper metals are covered with a thin layer of a more expensive metal so that the item looks expensive but has actually been made fairly cheaply.

Others, tin cans, for example, are made from steel that’s coated in a thin layer of a metal that won’t rust, to protect the steel from the elements.

It is possible to join three and four separate metals together; this is called tri-metal and tetra-metal.

Application of Bimetallic thermometer

  • use in control devices
  • use in air conditioning thermostats
  • process application such as refineries, oil burners, tire vulcanizers etc.

Advantages of bimetallic thermometers

They are simple, robust and inexpensive

Their accuracy is between +or- 2% to 5% of the scale

They can withstand 50% over a range in temperatures

They can be used where ever a mercury-in-glass thermometer is used

Limitations of a bimetallic thermometer

They are not recommended for temperature above 400’C

When regularly used, the bimetallic may permanently deform, which inturn will introduce errors

Different common forms of bimetallic sensors

  • Helix type
  • Spiral type
  • Cantilever type
  • Flat type

                                       

Choosing a thermometer

When selecting a thermometer, it is important to consider

  • the dial or case size
  • stem or capillary length
  • the connection type
  • temperature range

To ensure safety and accuracy, thermometers should be selected while giving consideration to the measured media and the ambient operating conditions.

Improper application may be detrimental to the thermometer, causing failure and possible personal injury or property damage.

Knowing the environment and media that the thermometer will be subjected to is also essential. This information will determine what type of thermometer is required and if thermowells are necessary.

Temperature measurement errors to keep in mind: conduction, convection, radiation, response time, noise, grounding issues and shorts (especially on metal surfaces).

Bimetal thermometer WIKA model 55 Bimetal thermometer WIKA model 55Bimetal thermometer WIKA model A43

 

Saba Dejlah is a big supplier at UAE from any kinds of thermometers,thermowells,…
We can supply from Wika,…

If this article was useful for you, kindly inform us and we will be happy if you put you comments her.

 

 

Unit of Temperature

Unit of Temperature

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Unit of Temperature

In this article, we introduce the Unit of Temperature and the method of converting each of these units to each other.

Many devices have been invented to accurately measure temperature. It all started with the establishment of a temperature scale. This scale transformed the measurement of temperature into meaningful numbers.

What is the temperature?

Temperature is a measure of the internal thermal energy state of a substance. It represents how much vibrational energy exists in the molecules of a liquid or solid, or the translational energy (speed of movement) of molecules in a gas.

Fahrenheit

The degree Fahrenheit ( o F) is the unit of temperature used by most people in the United States in describing weather.

The scale derives its name from a German-born physicist, Daniel Gabriel Fahrenheit, who is recognized as having invented it. At standard Earth-atmospheric sea-level pressure, pure water freezes at 32 o F and boils at +212 o F.

Celsius scale

The Celsius scale, previously known as the centigrade scale, is a temperature scale used by the International System of Units (SI).

As an SI derived unit, it is used by all countries except the United States, the Bahamas, Belize, the Cayman Islands, and Liberia.

It is named after the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale.

The degree Celsius (°C) can refer to a specific temperature on the Celsius scale or a unit to indicate a difference between two temperatures or uncertainty.

Before being renamed to honor Anders Celsius in 1948, the unit was called centigrade, from the Latin centum, which means 100, and grades, which means steps.

Kelvin Scale

The Kelvin Scale is a thermometric scale used in physical science to describe the absolute temperature of an object, substance, or area.

While Fahrenheit and Celsius scales measure temperature, the Kelvin Scale defines temperatures relative to an object’s thermodynamic movement.

As a result, the Kelvin Scale does not use degrees, but simply a number followed by “K” for Kelvin.

The Kelvin Scale begins at absolute zero (equivalent to -273.15° C), which is the temperature at which all objects stop moving, and ends at the triple point of water (equivalent to 0.01°C), which is the temperature at which water exists in all three states of matter simultaneously.

temperature unit conversion

 From Celsius to Fahrenheit

  • [°F] = [°C] ×9/5   + 32

From Fahrenheit to Celsius

  • [°C] = ([°F] − 32) ×5/9

From Celsius to Kelvin

  • [K] = [°C] + 273.15

From Kelvin to Celsius

  • [°C] = [K] − 273.15

From Kelvin to Fahrenheit

  • [°F] = [K] × 9/5   − 459.67

From Fahrenheit to Kelvin

  • [K] = ([°F] + 459.67) *5/9

Here you can to use temperature unit converter.

Also, you can see what you can find the store of Saba Dejlah to buy thermometer product.

You can buy the thermometer from UAE and we can send it to all of the worlds.

Temperature

Temperature

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Temperature

Temperature measurement in today’s industrial environment encompasses a wide variety of needs and applications.

To meet this wide array of needs the process controls industry has developed a large number of sensors and devices to handle this demand.

Many methods have been developed for measuring temperature.

Temperature measurement can be classified into a few general categories:

  • Thermometers
  • Probes
  • Non-contact

Thermometers are the oldest of the group.

Thermometers

A thermometer is an instrument that measures temperature. It can measure the temperature of a solid such as food, a liquid such as water, or a gas such as air.

The three most common units of measurement for temperature are Celsius, Fahrenheit, and kelvin.

Bimetal Thermometer

Bimetallic thermometers are made up of bimetallic strips formed by joining two different metals having different thermal expansion coefficients.

Basically, bimetallic strip is a mechanical element which can sense temperature and transform it into a mechanical displacement.

This mechanical action from the bimetallic strip can be used to activate a switching mechanism for getting electronic output. Also it can be attached to the pointer of a measuring instrument or a position indicator.

Various techniques such as riveting, bolting, fastening can be used to bond two layers of diverse metals in a bimetallic strip.

How ever the most commonly used method is welding. Since two metals are employed to construct a bimetallic strip, hence the name.

Probes

Following the development of the thermometer, the next step in the evolution of temperature measurement was the development of the temperature probe. In 1826 an inventor named Becquerel used the first platinum-vs-palladium thermocouple.

Prior to this time all temperature measurement was done with liquid or gas filled thermometers. The invention of the thermocouple ushered in a whole new wave of development, culminating in what we know today as practical thermometry.

This resistance element was the first in a series of devices that are not classified as probes or transducers. These fall into three general categories:

  • Resistance elements
  • Thermopiles
  • Semiconductor

Resistance elements

Resistance elements were the first probes that came into being. Early inventors understood the relationship between temperature and the resistance of different elements. This gave rise to a series of elements called thermistors.

Thermistors

The thermistor is a device that changes its electrical resistance with temperature. In particular materials with predictable values of change are most desirable. The original thermistors were made of loops of resistance wire, but the typical thermistor in use today is a sintered semiconductor material that is capable of large changes in resistance for a small change in temperature.

RTD

The Resistance Temperature Detector (RTD) technically includes thermistor devices, however the term ‘RTD’ has come to stand for the specialized pure metal detector rather than the more generic semiconductor resistance element. These pure metal devices are highly accurate and stable over long periods of time.

Here many kinds of temperature products from the best brands at the whole of the world.
All the temperature products have made from the best materials that fit with your process and varios of media.
So Saba Dejlah can help you to choose the best thermometer.

You can choose from WIKA,Ashcroft ,….and any brand that you want.