Thermocouples & Thermoresistances0 pages

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OTFIL

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Thermocouples & Thermoresistances

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Thermocouples

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Temperature probes are basically two wires with particular thermoelectric features, electrically insulated from each

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other and from the external protection body. This type of temperature gauge is very reliable and quickly responding.

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Depending on their various construction features, they are individually optimized to fully fit in a great number of

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industrial applications. The most significant input data needed to design a temperature probe are operative

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temperature range and working conditions.

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MgO Insulation Thermocouples

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MgO-insulated thermocouples are made of two or more wires, inside a highly compacted MgO insulation powder.

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Various materials can be used for the external metallic body, according to the specific working conditions. MgO-

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insulated thermocouples are manufactured and tested according to ASTM E608, and comply to ANSI MC 96.1 or

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DIN 43710 standards.

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Conventional Insulation Thermocouples

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The thermocouple leads are inserted in ceramic insulators, that are housed, together with alumina powder, in

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protective bodies to ANSI/DIN specifications. The main application of these temperature gauges is when no

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vibrations, mechanical stresses or pressure loads are applied.

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Thermocouple Junction Types

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There are 3 types of wire junction in thermocouples. The type shall be chosen according to the characteristics of the

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application. The below comparison chart might help.

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E G U

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<i=- l i I

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Symbol	Type	Response Time	In Corrosive Environments	With Vibrations	Other Features
E	EXPOSED JUNCTION	Very short	Not good	Not good	Shall be handled carefully to avoid damage to the junction.
G	GROUNDED JUNCTION	Short	Good	Not good	Very good with high pressures (up to 3500 Kg/cm2, or 350 MPa).
U	UNGROUNDED JUNCTION	Longer	Very good	Very good	Very good whenever parasitic emf could affect accurate measurement.

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Thermocouples, PDF-TCR-011-E-1/10

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