Principals of Industrial Measurements- Weaver- Thermocouples

Study yellow section of ANSI code sheet

ok

In thermocouples, the red wire is always…

negative

J thermocouples are…

not recommended for cold temperatures

K thermocouples are…

the most popular

T thermocouples are…

good where moisture is present, and for low temp and cryogenic applications

K type thermocouples are switching to green instead of yellow because…

when the yellow wire wears out it turns to white, which could cause it to be confused with J type thermocouples

J type wires are…

white and red

K type wires are…

yellow and red, but switching to green and red

T type wires are…

blue and red

E type wires are…`

purple and red

A beaded wire thermocouple is…

the simplest form of thermocouple

beaded wire thermocouples are a good choice for….

measurement of gas temperature

What are the three thermocouple probe tip types

Grounded, ungrounded, and exposed

Why might a exposed probe tip be desired

it is the fastest

What is bad about ungrounded probe tips?

it is the slowest

exposed junction thermocouples are best suited for…

air measurement

Why would a thermocouple require a flat and thin junction?

when working with a rigid solid surface to ensure maximum contact

When does a ground loop occur?

when there are two or more paths to ground with different electrical potentials in a circuit

Why is it important to ensure the thermocouple circuit is grounded at only one point?

to ensure accurate and reliable temperature measurements

What is a thermocouple?

a temperature sensor that consists of two dissimilar metal wires joined at one end

What are thermocouple readings measured in?

millivolts

What kind of metal are RTDs made of?

platnium

Why are thermocouples desired over RTDS

They withstand higher temperatures, are more durable, and less expensive

What is the reference point for thermocouples?

32 degrees Fahrenheit