What device or system of piping maintains a water seal in a trap for infrequent use?

A trap primer is specifically designed to maintain a water seal in a plumbing trap, particularly for infrequently used fixtures. The primary function of a trap is to create a barrier of water that prevents sewer gases from escaping into occupied spaces. Over time, especially with infrequent usage, the water in a trap can evaporate, breaking this seal and allowing harmful gases to enter.

A trap primer works by automatically introducing water into the trap when it detects that the fixture has not been used for a certain duration. This guarantees that the water seal is preserved, ensuring proper functioning and safety of the plumbing system.

While other options like backflow preventers and pump systems serve important roles in plumbing systems, they do not directly address the issue of maintaining a water seal in traps specifically designed for infrequent use. Backflow preventers prevent contamination of the potable water supply from backflow conditions, and pump systems are used to move water or wastewater, not to maintain seals in traps. Drainage seal, while it may sound relevant, is not a recognized term or device in plumbing codes that addresses the water seal function in traps.