Final answer:
A trap primer is a device and system of piping that maintains a water seal in a remote trap to prevent sewer gases from entering the living or working space.
Step-by-step explanation:
A device that maintains a water seal in a remote trap is called a trap primer.
This device and system of piping ensures that there is always water in the trap to prevent sewer gases from entering the living or working space.
The trap primer is typically connected to a water supply line and is triggered by a small amount of water flowing into the trap, which replenishes the water seal.