A trap primer (or trap seal primer) is a

plumbing Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Heating and cooling (HVAC), waste removal, and potable water delivery ...

device or

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...

that adds water to traps. The water seals in traps are needed to prevent

sewer gas Sewer gas is a complex, generally obnoxious smelling mixture of toxic and nontoxic gases produced and collected in sewage systems by the decomposition of organic household or industrial wastes, typical components of sewage. Sewer gases may inc ...

es from entering buildings, but because this water is exposed to the air, it is subject to

evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...

over time in infrequently used floor drains, leading to the release of sewer gas into the environment. The trap primer mitigates this problem by injecting water, either directly or indirectly, into the trap to maintain the water seal indefinitely.

Building code A building code (also building control or building regulations) is a set of rules that specify the standards for constructed objects such as buildings and non-building structures. Buildings must conform to the code to obtain planning permission ...

s may require trap primers for traps in certain locations or situations, usually those in which industry experience has shown that they are likely to dry out. The most common requirement is for basement floor drains, which are only used when the basement floods. Sometimes they are also installed in locations where the plumbing code does not require a primer because of a high probability of the trap drying out, but because of a nearby ignition source and the explosion hazard in the event that the trap did leak sewer gas. Most designs require installation in an accessible location where periodic maintenance can be performed.

Types

There are many types of trap primers. The simplest, typically for a floor drain's trap, is simply a connection from a nearby

sink A sink is a bowl-shaped plumbing fixture for washing hands, dishwashing, and other purposes. Sinks have a tap (faucet) that supply hot and cold water and may include a spray feature to be used for faster rinsing. They also include a drain to ...

's drain so that when the sink is used, some of the water flow is diverted into one or more traps. More common is a primer that is connected to the

potable water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, ag ...

supply and activates when pressure fluctuations are sensed, such as the flushing of a nearby

water closet A flush toilet (also known as a flushing toilet, water closet (WC) – see also toilet names) is a toilet that disposes of human waste (principally urine and feces) by using the force of water to ''flush'' it through a drainpipe to another loca ...

. Others depend on occupancy sensors or timers.{{cite web , url=http://www.mifab.com/Catalog/Library/TSP-2014_Trap_Seal_Primer_Selection_Guide.pdf , title=Trap Seal Primer Selection Guide , date=2014 , website=www.mifab.com , publisher=MIFAB , access-date=1 March 2016 Several manufacturers (e.g., Moen) produce laundry faucets with a built-in trap seal primer outlet.

Types

References

See also