RS PRO Sensors Thermocouple Guide
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THERMOCOUPLE SELECTION GUIDE

Buy this and more at rspro.com THERMOCOUPLE & PLATINUM RESISTANCE THERMOMETRY - AT A GLANCE Selecting sensor cables: Guide to insulation & covering Colour codes: thermocouple connectors, extension and compensating wires and cables Which insulation material? Useable temperature range Application notes Good general purpose insulation for ‘light’ environments. Waterproof and very flexible. PTFE (taped & wrapped) Resistant to oils, acids other adverse agents and fluids. Good mechanical strength and flexibility. PTFE better for steam/elevated pressure environments. Resistant to oils, acids other...

Buy this and more at rspro.com COMPARISON OF SENSOR TYPES PLATINUM RESISTANCE THERMOMETER Thermoelement, two dissimilar metals/alloys Platinum-wire wound or flatfilm resistor Ceramic (metal oxides) Long term Stability Variable, Prone to ageing Temperature range Sheathed – slow Exposed tip – fast 0.1 to 10 secs typical Wirewound – slow Film – faster 1-50 secs typical generally fast 0.05 to 2.5 secs typical Constant current required Most types non-linear Fairly linear Short cable runs satisfactory 3 & 4 wire – low. 2 wire – high Rarely susceptible Potentiometric input. Cold junction...

DIFFERENT THERMOCOUPLE JUNCTIONS Sheathed Thermocouples – Measuring Junctions Many alternative sheath materials are used to protect thermoelements, three alternative tip configurations are usually offered: An exposed (measuring) junction is recommended for the measurement of flowing or static non-corrosive gas temperature when the greatest sensitivity and quickest response is required. An insulated junction is more suitable for corrosive media although the thermal response is slower. In some applications where more than one thermocouple connects to the associated instrumentation, insulation...

IMMERSION OR SURFACE TEMPERATURE MEASUREMENT Buy this and more at rspro.com Surface Temperature Measurement Thermocouple assemblies are “tip” sensing devices which lends them to both surface and immersion applications depending on their construction. However, immersion types must be used carefully to avoid errors due to stem conduction; this is heat flow to or from the sheath and into or away from the process which can result in a high or low reading respectively. A general rule is to immerse into the medium to a minimum of 4 times the outside diameter of the sheath; no quantitative data...

Buy this and more at rspro.com COMPARISON OF SHEATH MATERIALS SHEATH MATERIAL Refractory Oxide recrystallised, e.g. Alumina Impervious Good choice for rare metal thermocouples. Good resistance to chemical attack. Mechanically strong but severe thermal shock should be avoided. Forging iron & steel, incinerators, carburizing and hardening in heat treatment, continuous furnaces and glass lehrs. Silicon Carbide (Porous) Good level of protection even in severe conditions. Good resistance to reasonable levels of thermal shock. Mechanically strong when thick wall is specified but becomes brittle...

Buy this and more at rspro.com Resistance Thermometers utilise a high precision sensing resistor, usually platinum, the resistance value of which increases with temperature. The dominant standard adopted internationally is the Pt100 which has a resistance value of 100.0 Ohms at 0°C and a change of 38.50 Ohms between 0 and 100°C (the fundamental interval). Thermocouples comprise a thermoelement which is a junction of two specifield, dissimilar alloys and a suitable two wire extension lead. The junction is a short circuit only, the EMF is generated in the temperature gradient between the hot...

ADVANTAGES OF MINERAL INSULATED THERMOCOUPLES Buy this and more at rspro.com M.I. (Mineral Insulated) cable is used to insulate thermocouple wires from one another and from the metal sheath that surrounds them. MI Cable has two (or four when duplex) thermocouple wires running down the middle of the tube. The tube is then filled with magnesium oxide powder and compacted to ensure the wires are properly insulated and separated. MI cable helps to protect the thermocouple wire from corrosion and electrical interference. • Long stable life • Small size • High insulation resistance • Rapid...

Buy this and more at rspro.com MINERAL INSULATED THERMOCOUPLES Plug Termination TYPE TEMPERATURE RANGE Miniature Plug Miniature Plug Miniature Plug TEMPERATURE RANGE Plain Pot with Tails Termination TYPE CABLE TYPE CABLE LENGTH CABLE COLOUR Threaded Pot with Tails Termination TYPE CABLE TYPE CABLE LENGTH TEMPERATURE RANGE This is just a small selection of Mineral Insulated Thermocouples offered by RS P

Buy this and more at rspro.com MINERAL INSULATED THERMOCOUPLES Thermocouples with Compact KNS Terminal Head TYPE HEAD TYPE TEMPERATURE RANGE Thermocouple with Ceramic Plug Termination TYPE HEAD TYPE PROBE TEMPERATURE RANGE PLUG TEMPERATURE RANGE Miniature ceramic plug + Socket Miniature ceramic plug + Socket Miniature ceramic plug + Socket Miniature ceramic plug + Socket This is just a small selection of Mineral Insulated Thermocouples of

Buy this and more at rspro.com STAINLESS STEEL FABRICATED THERMOPOCKETS Thermocouples with Compact KNS Terminal Head SUITE PROBE DIA • 25.4mm across flats hex (pockets to suit 6.0mm probe) • 1/2” BSP parallel process thread • Suitable with 3.0 or 6.0mm diameter probes WITH FITTING TO SUIT • Fabricated 316 stainless steel thermopocket IMMERSION LENGTH Stainless steel thermopockets of numerous sizes, designed for use with industrial style temperature probes to provide protection for the sheathing from corrosive media, and to facilitate probe replacement without disturbing the process. PROCESS...

Buy this and more at rspro.com FABRICATED AND SPECIALIST THERMOCOUPLES Magnet Thermocouple TYPE TEMPERATURE RANGE PFA Teflon® insulated with stainless steel over-braid Miniature Plug PFA Teflon® insulated with stainless steel over-braid Miniature Plug TEMPERATURE RANGE PFA Teflon® insulated twin twisted Miniature Plug PFA Teflon® insulated twin twisted Miniature Plug TEMPERATURE RANGE PFA Teflon® insulated twin twisted Miniature Plug PFA Teflon® insulated twin twisted Miniature Plug Button Magnet Magnetic Strip This is just a small selection of Fabricated and Specialist Thermocouples offere