Technical Information

Temperature FAQs

How long does it take to get a reading?

Multiply the specified time constant by five.

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How do I determine the accuracy of a system (probe and meter)?

Add together the stated accuracy of each.

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When there are two accuracy statements, which one is correct?

The general rule is to use the accuracy statement that gives the greatest error in the measuring situation.

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What are the benefits of grounded, ungrounded, and exposed probe junctions?

GROUNDED JUNCTIONS are welded to the tip of the sheath with wires completely sealed from contaminants. They offer good response times and are ideal for measuring the temperature of static or flowing corrosive gases and liquids.

UNGROUNDED JUNCTIONS are sealed, insulated from the protective sheath, and electrically isolated. They have longer response times than grounded or exposed junctions and are used for conductive solutions or where isolation of the measuring circuitry is required.

EXPOSED JUNCTIONS have the fastest response times and are ideal for measuring rapid temperature changes. Clear coating on most models provides a humidity barrier for the thermocouple. Do not use exposed junctions with corrosive fluids or atmospheres.

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What colors are the lead wires of each thermocouple type?

A: In the U.S.A:

Type K = yellow-red
Type J = white-red
Type T = blue-red
Type E = purple-red
Red is always negative in thermocouples.

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How far can I transmit my temperature signal?

In an electrically clean environment, thermocouple, RTD, and thermistor signals can be transmitted up to 200 feet (61 meters) without amplification. To transmit a thermocouple signal over greater distances, use thermocouple extension wire; for RTD and thermistor signals, use shielded copper extension wire.

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How do I measure samples without contacting them?

Use an infrared thermometer.

Thermo Fisher Scientific Inc.
Last updated on 02 November 2006. Copyright © 2004 Eutech Instruments Pte Ltd.