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Multi-Point Thermocouple

What is Multi-Point Thermocouple?

Multi-point thermocouples are used to measure more than one temperature point through a single access point. The sensor has multiple temperatures input along the length of the sensor to calculate an accurate temperature profile. This sensor can be equipped with up to 60 points along the length with a single penetration point. These sensors are mostly used in chemical and petroleum industries for temperature profiling of reactors, crackers, and liquefied gas in tanks. — The design and dimensions of the multi-point thermocouples differ depending on the shape and size of the container, position of the sensors, service required, pressure, temperature and ambient environment of where the thermocouple has to be installed and where the output is required.

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Multipoint Thermocouple & Its Various Designs

A thermocouple is commonly used sensor to measure process temperature and well known in modern control applications due to their moderately minimal effort and wide estimation ranges. Specifically, thermocouples dominate at estimating high temperatures where other regular sensor types can't work.

Multipoint Thermocouples :

Multipoint thermocouples precisely measure the temperature in different areas along the length of the sensor. They are especially recommended for distinguishing hotspots, uneven flow and are utilized in an assortment of uses where there is a huge or complex cycle and precise temperature is basic. Detecting temperature at a remote area during a cycle is worthy for some applications since temperature inclinations are regularly irrelevant. Introducing different, free temperature sensors might be unreasonable because of cost or space impediments.

In numerous applications, logging temperature profile of heaters, measure lines, compound reactors, petroleum treatment facilities, and petrochemical enterprises is required. There is the need to measure and screen the temperature in different areas, to guarantee the cycle is cost-proficient, precise, and safe. Multipoint thermocouples are best solutions for such requirements. It can measure from -200°C to 1250°C.

Various designs of Multipoint Thermocouple :

Multipoint thermocouples are available in different designs, few are :

Freely Suspended multi-point thermocouple: With the advanced flexible multipoint thermocouple model, you get the upside of genuine temperature profiling in the vessel to identify hotspots, directing impacts, and misdistribution of material with a quick response time of 4 to 8 seconds. The sensors are directed around the perimeter of the reactors and then inwards to the necessary measuring point. These sensors are flexible and can be coiled for transportations.

Multi-point thermocouple with heat sink block: In this type, the sensor is attached with a heat transfer block to give double protection. The heat sink block is welded with the vessel body where the measuring sensor must be connected. The replacement & removal of sensor during operation is permitted in this design. The sensor leans against the heat sink block to give a faster response time.

Spring-loaded multi-point thermocouple: The design is outfitted with a bimetal spring-loaded arrangement to an individual sensor, to give positive contact between the measuring sensor and protection tube. The bimetallic spring is introduced into the protection tube in the unloaded position, and the association is accomplished when the heat is applied during the process.

Multi-point thermocouple with guide tubes: Guide tubes are accommodated with every sensor to ensure exact placing of the sensor. In this type, guided tubes are attached to process, so doesn’t require re-welding on process tubes while replacing thermocouples. These guided tubes can be spring loaded to make sure the sensor is in contact with the inner wall.

Multi-point thermocouple with Radial Arrangement: In this type, individual elements can be routed in any cylindrical shape and radial arrangement prevents possible influence on the function of the catalyst. We can achieve short response time and get fast information of process, which helps to have fast & precise controlling.

Highlights of Multipoint thermocouple Assembly :

• Monitor temperatures in process to guarantee a protected, precise, and cost proficient cycle.

• Multiple detecting focuses with just a single termination point.

• Different thermocouples with various MOC conceivable.

• Construction allows the client to replace individual elements without interrupting whole process.

• Effectively measure temperature profile for different applications.

• Customized solutions available as per application requirement.

• All sensors are completely Metal Sheathed MI (mineral insulated) type.

Major Industries served:

• Refineries and Petrochemical.

• Crude Oil and Gas Fertilizer.

• Chemical and petrochemical enterprises.

• Reactors and Distillation fractionators.

• Catalytic reforming process.

• Fuel depots, hydrocrackers and hydrotreaters.

• Fluid catalytic cracking unit

If you want to get a quote, for more information or any specific request, please contact our services. We shall get back to you as soon as possible.

#multipoint thermocouples #Thermocouples #temperature gauge #thermowells #thermocouple cable #black body calibrator

Black Body Calibrator :

Black Body is the most ideal calibrator of an infrared thermometer. This is because black bodies have an Emissivity equal to 1.000.A perfect blackbody only would have an emissivity of 1.000. This would take place in a system where no light or radiation could escape and all the radiation shall remain inside forever. In the real world, there is no such thing as a perfect blackbody for IR thermometry. This is because there would be no opening for taking a measurement in such a system. However, the perfect blackbody is a good prototype for modeling thermal radiation. Emissivity is the ratio of energy radiated by a particular material to energy radiated by a black body at the same temperature. A true black body would have an emissivity = 1 while any real object would have emissivity < 1. Emissivity is a dimensionless quantity. Every material radiates energy. The amount of radiated power is dependent on the material’s temperature and the material’s emissivity. IR thermometers make use of this. They measure the amount of energy radiated by an object in an infrared band. This infrared band can vary from 1 micrometer to 14 micrometers. Depending on the wavelength range IR thermometers use different types of sensors to determine the temperature. They calculate the temperature based on this measured power and the material’s emissivity.

Technical aspects of black body calibrators :

Emissivity is one of the major sources of error in infrared measurements. Knowledge of the emissivity of the measured surface is of great value to any user of an IR thermometer. As so, great care should be taken to know the effects of emissivity of the surface when measuring it. Deviation in the assumed emissivity of the measuring target body would lead to a significant error in temperature measurement. Proper knowledge of emissivity and background temperature should be considered when measuring a surface temperature. These factors are even more important when using an IR thermometer calibrator. Paying attention to these factors will provide better calibration and better IR metrology.

Planck's Law :

The mathematical equation describing the spectral power radiated by a perfect blackbody for a given wavelength is Planck's Law. If Planck's Law is integrated over the entire electromagnetic spectrum, this gives us the Stefan-Boltzmann Law. This is the familiar T to the 4th law (T4). The problem with the Stefan- Boltzmann Law is that it is not limited to a specific band. To get such a number, we would need to integrate Planck's Law for the limits of this bandwidth. This integral cannot be solved analytically.

Effects of wave length :

Many charts can be found which lists the emissivity of various materials. These are good guides when looking for emissive properties of materials, but they do not tell us the correct value always because most material’s emissivity varies with wavelength. In other

words, materials have a spectral emissivity response. An IR thermometer integrates the emissivity within its bandwidth. One study showed that the emissivity in the 8 - 14μm band varied between 0.90 and 0.97 with a dependence on wavelength. Other studies

show a similar range of emissivities. Effect of Temperature Emissivity can also vary with temperature. The other effect that temperature can have is as temperature changes, the amount of energy measure by the IR thermometer shifts within the band. As temperature rises, the energy emitted by the surface shifts from the higher to the lower wavelengths as predicted by the Wien's Displacement Law. This causes the effective emissivity the IR thermometer measures to shift from that of the higher end of the bandwidth to that of the lower end as temperature rises.

Cavities :

Practically, there is no such thing as a perfect blackbody in the real world. Manufactures of Black bodies make different shapes and geometries which can be used or which can act as near perfect blackbody. A near-perfect Black Body will have its emissivity close to 1

but not exactly equal to 1. A good approximation of a perfect blackbody is a cavity. A cavity can have different shapes; it can be a sphere, cylinder, cone or a combination of these. It must have a well-controlled uniform temperature on its surfaces. The total emissivity of a cavity depends on its geometry but is generally close to 1.000. Cavities will typically have an emissivity of 0.99, 0.999, etc. In simple terms, we can understand that as emissivity is more close to 1, it acts as a better approximation for a perfect Black Body. A cavity is not always the best for all types of IR thermometers, especially handheld instruments. This is due to the optical scheme of these instruments. For an error-free measurement, the spot size of the IR thermometer should lie inside the radiating area. The spot size is the amount of area the IR thermometer sees when measuring temperature on a surface. Surface Black bodies are made which have a large surface area radiating energy and the whole surface is very uniform in terms of temperature and emissivity.

Error caused by Emissivity :

Emissivity contributes to uncertainty when using a surface Black Body. If the user doesn’t have proper knowledge of the emissivity of the surface then emissivity can be a major contributor in the error caused in the temperature measurement. Users of these Black Body or IR Calibrators should have a temperature is a surface at 0°C measured in the 8 – 14 μm band. If the user of the IR thermometer isstanding facing the target, the user could very well become the background. This could raise the background from 23°C to 37°C causing a 3.5°C error in the measurement.

Handling of Black Bodies :

When using a Black body, care must be taken not to damage the emissive surface. Damage can result from a number of sources. First, care must be taken not to get any foreign material on the surface of the calibrator. Even oil from your skin can damage the calibrator’s surface, especially when the surface is heated. The surface should not be cooled by any method other than natural convection. Forced air can often have oil or water in it. Even water can leave mineral deposits on the surface. Trying to cool the surface too quickly can also cause thermal shock to the emissive surface. The calibrator should not be left at a high temperature for an extended period of time. This can cause the emissivity of the surface to be degraded.

Black Body Product :

The Black Bodies available with us for different temperature ranges.

#black body calibrator #thermocouple cable #temperature sensors #temperature calibrator

K TYPE THERMOCOUPLE

Type K Thermocouple provides the widest operating temperature range. It comprises of a positive leg which is non-attractive and a negative leg which is attractive. In K Type Thermocouple customary base metal is utilized because of which it can work high temperature and can give amplest working temperature range.

#k type thermocouple #black body calibrator #optical pyrometer #compenating cable

K TYPE THERMOCOUPLE

Introduction:- Type K Thermocouple provides the widest operating temperature range. It comprises of a positive leg which is non-attractive and a negative leg which is attractive. In K Type Thermocouple customary base metal is utilized because of which it can work high temperature and can give amplest working temperature range.

Nickel, which is magnetic in nature. The characteristic shown by K Type Thermocouple is that they undergo a deviation in output when magnetic material reaches its Curie Point, at around 185 °C. K Type thermocouple work very well in an oxidizing atmosphere at temperatures up to 1260°C (2300°F) and its tolerance class is ± 1.5 K between -40 and 375 °C.

Why prefer K Type Thermocouple:- • One of the major advantages of K-type thermocouples over other thermocouples is it can function in rugged environmental conditions & in various atmospheres. • It has an integrated composition of Chromel and Alumel wires has a range of -270 °C to 1260 °C and output of -6.4 to 54.9 mV over the maximum temperature range. • Also known as general purpose thermocouple due to its wide range of temperature. • Type K has a longer life than Type J as in Type J Fe (iron) wire oxidizes rapidly, especially at higher temperatures. • They are inexpensive. • Have a fast response time. • Small in size and are reliable. • Generally used at temperatures above 540 degrees C. Composition:- In K Type Thermocouple positive leg is made out of 90% nickel, 10%chromium, and a negative leg is made out of 95% nickel, 2% aluminum, 2% manganese, and 1% silicon. These are the most widely recognized broadly useful thermocouple with an affectability of approx 41µV/°C.Type K Insulation Material:- In Type K Thermocouple mainly two types of insulation are used firstly Ceramic beads insulation is used as it is a lightweight insulating product. It is produced using high virtue alumino-silicate materials. It has a low warm mass which implies that it doesn't hold heat, low warm conductivity, and is an incredibly compelling protection material as it can withstand a high temperature of 1260 °C so it a most appropriate material for Type K thermocouple. Also compacted mineral protection and external metal sheath (MgO) is utilized. Magnesium Oxide has a high dielectric quality, reacts rapidly to temperature changes, and is entirely sturdy. The regular composition having the standard quality Mgo with the purity MgO and AI203. Magnesium Oxide protection is suggested for K Type thermocouple when Thermocouple are to be submerged in fluids, high dampness, destructive gases, or high weights. The thermocouple can be framed to arrive at in any case unavailable regions. Temperature Range :- To discover the fitting scope of thermocouples we should utilize proper wire in light of the fact that various wires measure different temperature ranges. Of the four significant thermocouple types, type K covers the largest reach:- • Thermocouple grade wire, –454 to 2,300F (–270 to 1260°C) • Extension wire, 32 to 392F (0 to 200°C) Accuracy (whichever is greater): • Standard: +/- 2.2°C or +/- .75% • Special Limits of Error: +/- l.l°C or 0.4% Tolerance Class:- EMF Vs Temperature Graph for K Type Thermocouple:- Pros And Cons:- Pros • To measure temperature it provides good linearity of emf. • It provides good resistance against oxidation below 1000 °C (1600°F). • Highly stable output. • Comparitively cost-effective than other thermocouples. Cons • Not suitable for reducing atmosphere but can withstand metallic vapor. • Aging of the emf characteristic, when compared to noble metal thermocouples (B, R, and S). • Not suitable for vacuum applications due to vaporization of chromium in the positive element. • Green-Rotis phenomenon may occur due to low oxygen level for the thermocouples which are used between 815°C to 1040°C (1500°F to 1900°F). • Type K thermocouples should not be used in a Sulphuric environment since both elements will rapidly corrode and the negative element will eventually fail mechanically due to becoming brittle. Uses:- They are generally utilized for applications at temperatures over 550 °C up to the most extreme working weight of the thermocouple. • They are used in many industries like Steel & Iron to monitor temperature & chemistry throughout the steel making process. • Used for testing temperatures associated with process plants e.g. chemical production and petroleum refineries • Used for Testing of heating appliance safety. • Type K is commonly used in nuclear applications because of its relative radiation hardness.

#K type thermocouple #balck body calibrator #optical pyrometer #pyrometer #compenating cable #resistance temperature detector #rtd #temperature calibrator #thermal imager #temperature sensor #thermocouple #thermocouple cable

Temperature Measurement Technique For Aluminium Extrusion.

Temperature is the most important parameter in Aluminum Extrusion Process controlling Production, Wastage, Cost, Quality and the Life of the Press. Aluminum extrusion being dynamic processes, accurate continuous temperature control is possible only by using non-contact pyrometers.

Why use Multiwavelength IR Pyrometer in Aluminium Extrusion Lines?

1. Productivity – Allows for increased extrusion speed

2. Quality – Better profiles, reduces amount of scrap produced

3. Energy – Saves gas or electricity at the Die Furnace, Billet Furnace and Container electrical element.

Now let us have an brief overview of the applications,installation and models to be used to get targeted temperature measurement in Aluminium Extrusion

1. BILLET

Billets are heated in heating furnace to the required temperature, usually around 420-500 °C. The heating is intended to reduce the flow stress of the aluminum alloys and to avoid cracks and surface defects due to high temperature.

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