Question 378General Subjects - Assistant Engineer

The correct answer is D) rotor clearances. The capacity of a gear type rotary pump operated at a constant speed will decrease with an increase in the pump's rotor clearances. As the clearances between the rotors and the pump housing increase, it allows more fluid to leak back from the discharge side to the suction side, reducing the overall volumetric efficiency and capacity of the pump. The other options are incorrect because: A) Discharge volume is not a factor that affects pump capacity when operated at a constant speed; B) Suction pressure is a different parameter that affects pump performance but not necessarily the capacity; and C) Torque rating is not directly related to the pump's capacity.