Final answer:
The minimum size vent pipe for a 4-inch trap is typically 1.5 inches in diameter according to building codes, which ensure proper air flow and pressure balance in a plumbing system.
Step-by-step explanation:
The question pertains to the minimum size vent pipe that may serve a 4-inch trap. Building codes typically dictate the size of the vent pipe needed for drainage systems, and these codes must be followed to ensure safe and efficient operation of the plumbing system. For a 4-inch trap, the minimum vent pipe size is typically 1.5 inches in diameter. This allows for proper air flow to balance the pressure within the drainage system, preventing negative pressure which could lead to trap siphonage and positive pressure causing blow-back of sewage gases. In practical applications within engineering, economizing and scaling considerations are often made, such as those described in the hypothetical Table 7.15 Comparing Pipes: Economies of Scale in the Chemical Industry, but the fundamental requirement for a vent pipe size is generally determined by code and the specifics of the plumbing system design.