In a duplex reciprocating feed water pump, the steam piston area must be how much larger than the water piston?

In a duplex reciprocating feed water pump, it is essential for the steam piston area to be larger than the water piston area to ensure that the pump operates effectively and efficiently. The correct answer states that the steam piston area must be 2 to 2.5 times larger than that of the water piston.

This relationship is primarily due to the differences in the forces applied and the pressures at which the steam and the water operate. Steam, being a gas, occupies a much larger volume compared to the liquid water at equivalent operating pressures. Furthermore, the steam must exert a sufficient force to overcome the resistance of the water being pumped.

When the steam piston area is 2 to 2.5 times larger, it generates enough power to move the water piston against the system pressure effectively. If the steam area were not large enough, the pump would struggle to achieve the necessary displacement and could fail to maintain the required water flow rate, leading to inefficiencies or operational failure.

Thus, this design ratio helps ensure reliable pump performance by providing the necessary mechanical advantage, enabling the steam pressure to control the action of the water piston appropriately without losing efficiency.