Under the UPC, what factors determine the size of gas piping?

The correct choice highlights key aspects that influence the sizing of gas piping under the Uniform Plumbing Code (UPC). The type of gas is crucial because different gases have varying properties, such as energy content and flow characteristics, which can affect how much gas is needed for efficient operation. The flow rate is equally important, as it determines the volume of gas required for appliances during peak demand. Finally, the length of the run affects pressure loss due to friction; longer runs may require larger pipe diameters to maintain adequate gas pressure at the appliance.

These three factors combined ensure that the gas piping system can safely and effectively deliver the necessary volume of gas to the appliances without causing pressure drop issues or risking insufficient supply during high demand periods.