A trap seal of any fixture should not be subjected to a pneumatic pressure differential of more than how many inches of water column?

A trap seal of any fixture should not be subjected to a pneumatic pressure differential of more than 1 inch of water column. This limit is established to prevent the trap seal from being siphoned or disturbed. If the pressure differential exceeds this threshold, it can lead to the loss of water in the trap, which is essential for preventing sewer gases from entering the building. The trap seal creates a barrier that keeps foul odors and pathogens at bay, and maintaining it is crucial for both health and safety.

The standard of 1 inch of water column is based on practical observations and testing that demonstrate this is the maximum safe level of pressure that can be exerted without risking the integrity of the trap seal. Exceeding this can compromise the effectiveness of the plumbing system and cause significant issues such as unpleasant odors or even health hazards from toxic gases.