Purpose of thermowells in temperature measurement In industrial service, thermowells are installed primarily to achieve which of the following goals when measuring temperature with probes or thermocouples?

Introduction / Context:
Thermowells are protective housings inserted into process lines and vessels so that temperature sensors can be installed, removed, and protected without breaching the process. Understanding their primary purpose avoids unrealistic expectations about response time or accuracy improvements.

Given Data / Assumptions:

• Thermowells are typically metallic tubes (e.g., stainless steel, alloy steels) immersed in the process.
• A sensor (thermocouple, RTD) sits inside, isolated from corrosive fluid and pressure.
• Heat must conduct through the well wall to the sensor.

Concept / Approach:
The principal function is mechanical and chemical protection: to guard the sensing element from corrosion, erosion, oxidation, pressure, and to permit safe removal. By interposing an extra thermal mass and conduction path, thermowells generally increase lag relative to a bare probe. They do not inherently increase sensitivity or guarantee “perfect fidelity.” Proper design (taper, immersion length) mitigates lag and vibration while preserving acceptable accuracy.

Step-by-Step Solution:

Verification / Alternative check:
Standards and best practices (e.g., ASME PTC, ISA) emphasise protection and safe maintenance as the key motivations for thermowells; response-time penalties are managed by geometry.

Why Other Options Are Wrong:

Common Pitfalls:
Expecting faster response with a thermowell; in fact, bare sensors are faster but less protected.

Final Answer:
guard against corrosive and oxidising action on thermocouple materials