The thermo-expansion feedwater regulator operates on which principle?

The thermo-expansion feedwater regulator operates on which principle?

• A. Expansion and contraction of a thermostatic element
• B. Direct pressure signal
• C. Manual valving
• D. Electric motor actuation

Answer: (A)

The regulator relies on expansion and contraction of a thermostatic element in response to temperature changes. In operation, a sensing bulb or element experiences boiler temperature and expands as it heats, pushing on a diaphragm or linkage to move the feedwater valve toward reduced flow. As temperature falls and the element contracts, the valve opens more to admit additional feedwater. This purely thermal, expansion-based action automatically modulates feedwater to maintain the desired boiler level. It doesn’t use a direct pressure signal, manual valving, or electric motor actuation.

The regulator relies on expansion and contraction of a thermostatic element in response to temperature changes. In operation, a sensing bulb or element experiences boiler temperature and expands as it heats, pushing on a diaphragm or linkage to move the feedwater valve toward reduced flow. As temperature falls and the element contracts, the valve opens more to admit additional feedwater. This purely thermal, expansion-based action automatically modulates feedwater to maintain the desired boiler level. It doesn’t use a direct pressure signal, manual valving, or electric motor actuation.