Question 387Motor Plants - Assistant Engineer

The correct answer is A) engine speed. In a Roots-type rotary blower, the volume of air delivered is directly proportional to the engine speed. This is because the Roots blower operates by trapping air between its rotating lobes and forcing it out of the outlet. As the engine speed increases, the blower rotates faster, which directly increases the volume of air delivered. The other options are incorrect because they are not the primary factor determining the air volume output of a Roots blower. Engine load, brake horsepower, and brake specific fuel consumption are not directly related to the volume of air delivered by the blower.