Bimetallic thermometer vs. industrial mercury-in-glass: which characteristic is nearly the same between the two instruments?

Introduction / Context:
Industrial temperature instruments such as bimetallic thermometers and mercury-in-glass thermometers are both widely used for direct, on-site indication. While their internal sensing principles differ, their usable field ranges commonly overlap. This question asks which key characteristic is “almost the same” for both instruments in typical plant practice.

Given Data / Assumptions:

• Bimetallic thermometers are mechanical devices using bonded dissimilar-metal strips that bend with temperature.
• Industrial mercury-in-glass thermometers use thermal expansion of mercury to indicate temperature.
• We compare broad, practical industrial ranges, accuracy classes, and typical dynamic response.

Concept / Approach:
Manufacturers commonly rate both devices to similar overall ranges covering sub-zero to several hundred degrees Celsius. However, accuracy classes and response times are not identical: mercury-in-glass typically provides better accuracy and resolution, and a faster response than many bimetallic designs of comparable size. Hence, the closest “same” attribute is the general measuring range available off-the-shelf, rather than accuracy or speed.

Step-by-Step Solution:

Verification / Alternative check:
Vendor datasheets show overlapping catalog ranges for both instrument types; accuracy classes typically differ (e.g., bimetal ±1.5–2% vs. mercury-in-glass near ±1% or better), and response times vary with bulb size and mounting.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming identical accuracy across instrument families; ratings depend on design, immersion, and calibration class.

Final Answer:
Temperature measuring range (about −40°C to 450°C)