Trap seal primers are used to protect a trap from loosing it's water seal and keeping sewer gasses from entering the building. Many areas require the installation of trap seal primers by code on floor drains located within industrial or commercial buildings. A trap seal primer is not typically used in residential construction but should be considered for emergency floor drains as people often forget about them.
Trap seal primers operate by allowing a small amount of water to be discharged whenever there is water flowing through the valve to a fixture. The water then drains down a section of tubing by gravity where it is connected to a floor drain. Trap seal primers must also incorporate an air gap or vacuum breaker to protect the water supply from cross connection to the sanitary system.
Trap seal primers come in a variety of joining methods: threaded, soldered, pex and compression.
Installation of trap seal primers
The installation of a trap seal primer begins when the rough in plumbing is installed, as the tubing running to the floor drain must be protected and hidden from view. A proper floor drain must also be installed; that comes with a manufactured female threaded inlet, to allow for a water tight connection to the trap seal primer's discharge tube. After the water lines are installed the trap seal primer is installed on a cold water line that serves a commonly used fixture and is connected on the outlet, to the tubing running to the trap.