What is the primary goal when selecting pipe sizes in plumbing design?

The primary goal when selecting pipe sizes in plumbing design is to meet the gallons per minute (GPM) demand without exceeding the maximum velocity. This approach ensures that the plumbing system can deliver the required water flow efficiently while minimizing the risk of problems such as excessive pressure loss, noise, and potential damage that can occur if the velocity of water in the pipes is too high.

Selecting the appropriate pipe size allows for optimal flow that meets the fixtures' demands, supporting both performance and longevity of the plumbing system. If the velocity is kept within acceptable limits, it helps to prevent erosion of the pipe material, reduces the chance of water hammer, and enhances overall system reliability.

While considerations like material cost, system velocity, and code compliance are important in the overall design process, they are secondary to ensuring that the system can adequately meet usage demands effectively. Compliance with building codes is essential, but it often follows from making proper selections based on flow rates and velocities, making those factors more critical in the initial size determination.