The purpose of the sentinel valve installed on a turbine casing is to __________.

Correct Answer: Option B — warn the engineer of excessive pressure in the low pressure turbine casing

A sentinel valve installed on a low-pressure turbine casing acts as an audible warning device. It exhausts a small amount of steam to the machinery space when pressure exceeds safe operational limits, alerting the engineer to potential overpressure conditions before relief diaphragms fail.