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Thermocouple selection :- Since a thermocouple can take many shapes and forms, it is important to understand how to properly select the right sensor. The most common criteria used to make that choice are temperature range, chemical resistance, abrasion and vibration resistance, and installation requirements. Installation requirements will also determine your choice of thermocouple probe.
There are different types of thermocouples and their applications may vary. An exposed thermocouple will work best when higher response times are required, but an underground thermocouple is better in corrosive environments. To help you determine the best thermocouple selection for your purposes, here are five ideas:
1. Determine the application where you will use the thermocouple sensor
Thermocouple can be used across industries and applications, so choosing the right one for your purposes begins with knowing how and where you want to use it.
2. Set the temperature range to which the probe will be exposed
Once you know the thermocouple temperature range you need, you can refer to our thermocouple range chart to help you determine which thermocouple is best for the temperature range you need Is.
A Type K thermocouple offers a wide temperature range and is one of the most commonly used thermocouples. However, if your thermocouple probe will be exposed to extreme temperatures, a type N thermocouple is more stable in high temperatures and a type T thermocouple is best for extremely low temperatures.
3. Determine how important a fast response time –
There are three types of thermocouple junctions: exposed, grounded or ungrounded. An open junction will provide the fastest response time. However, if the probe will be exposed to corrosive gas or high pressure, an exposed junction should not be used. An underground thermocouple provides the slowest response time but may still be the best option if it is desirable to electronically isolate the thermocouple and also to be shielded by a sheath.
4. Consider any chemical, abrasion or vibration resistance
An open thermocouple is limited in its use for non-corrosive applications. Both grounded or ungrounded thermocouples can be used in corrosive or high pressure environments, but if the thermocouple needs to be electronically isolated and shielded by a sheath, an underground probe is best. A grounded thermocouple is best if fast response times take priority in a corrosive environment
5. Consider any installation requirements
The thermocouple may need to be compatible with existing equipment. For example, the existing hole probe diameter can be determined