Why Fine or Sheet Thermocouples are superior

Comparison between different types of bare wire Thermocouples

Conventional Thermocouple	Fine Thermocouple	Sheet Thermocouple

Very poor response due to the small contact area of the ball shape tip. Therefore the heat transfer is minimised and a longer time is required to accurately measure the true temperature. This problem is compounded by the heat runaway through the large (200 micron) wire section.	Very fast response and high accuracy due to the tip being a welded point requiring virtually no heat up time. The wires have no heat runaway as they are very small, for example 25 micron.	The heat runaway through the large wire (eg 200 micron) is not a problem with the Sheet Thermocouple, due to the contact area being several thousand times larger than a conventional Thermocouple. Sheet Thermocouples will deliver your data with speed and accuracy.

Experimental result

We attached various Thermocouples to a stainless steel container, at the same height using caption tape. We then heated the container using hot water at a steady rate to ensure that the temperature around the surface of the container would rise at the same rate. The measured results speak for themselves!

EQUIPMENT USED:

Data logger : KEYENCE GM-3000
Sampling time : 100 ms

Experimental result

Comparison of response and accuracy

Faster response and higher accuracy

Characteristic and usage of various Thermocouples

Type of Thermocouple	Resistance of Thermocouple itself	Connectability to compensating wire	Strength	for small components	Accuracy	Response	Main usage
Conventional type Thermocouple (200 micron dia)	GOOD	GOOD	GOOD	POOR	POOR	POOR	When you do not require fast response or accuracy
Fine Thermocouple (25 & 50 micron dia)	GOOD	GOOD	POOR	GOOD	GOOD	GOOD	For small components or surface measurement
Sheet Thermocouple (40 micron thick)	GOOD	GOOD	GOOD	POOR	GOOD	GOOD	For surface measurement