What is a Wet Leg?

• A. A humidity analyzer
• B. A heat exchanger
• C. An impulse line filled with fluid that is compatible with the pressure measuring device
• D. A servo motor

Answer: (C)

A Wet Leg is the liquid-filled reference leg of a differential pressure impulse line. By filling the leg with a fluid compatible with the process and the pressure instrument, the pressure signal is transmitted through a liquid column rather than air, preserving the hydrostatic pressure and reducing errors from gas pockets, temperature changes, or leaks. This makes DP measurements more accurate in many industrial setups. The other options describe devices with different roles: a humidity analyzer measures moisture, a heat exchanger transfers heat, and a servo motor provides motion control, none of which relate to transmitting pressure via a filled impulse line.