Class 5 Boiler Practice Exam

How does the size of a pipe affect its flow capacity?

1. It decreases with size

2. It is unaffected by size

3. It increases exponentially with size

4. It only affects pressure loss

The correct answer is: It increases exponentially with size

The flow capacity of a pipe is fundamentally impacted by its size, and larger diameters allow for a greater volume of fluid to pass through. Flow capacity is typically described by the cross-sectional area of the pipe; as the diameter increases, the area through which fluid can flow also increases. This relationship is not linear; rather, it is based on the area of a circle (since pipes are cylindrical), resulting in the flow capacity increasing with the square of the diameter. As the diameter of the pipe doubles, the flow capacity increases by a factor of four, assuming that other conditions remain constant, such as fluid velocity and viscosity. This profound increase in flow capacity can be viewed as exponential in terms of practical applications, where doubling the diameter significantly enhances the volume that can move in a given time. While larger pipes do help improve fluid flow by minimizing pressure loss and turbulence, the primary factor affecting flow capacity remains size and cross-sectional area. Thus, the correct answer highlights the substantial impact of pipe size on flow capacity.