What is a pipe that carries the discharge from water closets (toilets) called?
Soil pipe A soil pipe carries discharge that contains human waste, which means anything from water closets, urinals and similar fixtures. A waste pipe carries liquid waste without fecal matter, like water from sinks and tubs.
In general, what is the minimum slope for a horizontal drainage pipe 2 inches in diameter?
1/4 inch per foot Both the IPC and the UPC use 1/4 inch of fall per foot as the basic minimum for small horizontal drains like a 2-inch line. That slope keeps water moving fast enough to carry solids. Larger pipes can be allowed a flatter slope, so check the sanitary drainage chapter of your code.
You need to join a horizontal branch drain to a horizontal building drain. Which fitting is the right choice?
A wye, or a combination wye and eighth bend A sanitary tee is meant for a horizontal pipe flowing into a vertical one. Where one horizontal drain joins another, codes call for a fitting with a long, gentle turn, like a wye or a combination wye and eighth bend. It brings the flow in at an angle, in the same direction as the main flow.
What is the main purpose of a plumbing vent system?
To protect trap seals from siphonage and back pressure Vents let air move in and out of the drainage system. That keeps air pressure near normal in the pipes, so moving water doesn’t suck a trap dry (siphonage) or push the seal out (back pressure). Vents also carry sewer gas safely outdoors, above the roof.
What is a wet vent?
A vent pipe that also carries drainage from other fixtures A wet vent is a pipe that does two jobs: it vents one or more fixtures and also carries drainage from others. Codes allow it only in set layouts and sizes, because the pipe has to stay big enough to carry water and still move air.
Where should a dry vent connect to a horizontal drain?
Above the centerline of the drain A dry vent is taken off above the centerline of a horizontal drain, then rises before running horizontally. That keeps waste water from flowing into the vent, where it could leave deposits and block it over time.
How deep should the water seal in a fixture trap be?
Between 2 and 4 inches Both the IPC and the UPC call for a trap seal of at least 2 inches and no more than 4 inches, with only a few exceptions. Less than 2 inches is easily lost to siphonage or evaporation. More than 4 inches makes the trap hold back solids and clog.
Which of these trap types is generally not allowed by plumbing codes?
An S-trap An S-trap drops straight down after the bend, so the rushing water can siphon the seal out of the trap. Codes generally prohibit S-traps. A vented P-trap is the standard choice for most fixtures.
Why shouldn’t a fixture drain through two traps, one after the other?
Air trapped between the traps can slow or stop drainage Codes don’t allow double trapping. The air caught between two water seals has nowhere to go, so it acts like a plug. The fixture drains slowly or not at all, and the seals can be forced out.
Which type of copper water tube has the thickest wall?
Type K For the same size tube, Type K has the thickest wall, Type L is in the middle and Type M is the thinnest. That’s why Type K is often used underground and for water services, where the pipe needs to be toughest.
What does a water hammer arrester do?
Absorbs the pressure surge when a valve closes quickly When a quick-closing valve, like a washing machine or dishwasher valve, snaps shut, the moving water slams to a stop. That sends a pressure spike through the pipe, which you hear as a bang. A water hammer arrester has an air or gas cushion that absorbs the spike.
The static water pressure coming into a building is above 80 psi. What do codes generally require?
A pressure-reducing valve Both the IPC and the UPC set 80 psi as the upper limit for static pressure in a building’s water system. Above that, you install an approved pressure-reducing valve to bring it down. High pressure wears out valves and fixtures and makes water hammer worse.
What is an air gap, in backflow prevention?
An open vertical distance between a water outlet and the flood-level rim of the fixture An air gap is an unobstructed vertical space between the end of a water outlet and the flood-level rim of the fixture or tank it fills. Because there’s no physical connection, dirty water can’t be pulled back into the supply. Codes set a minimum gap based on the size of the outlet.
A garden hose is left in a bucket of weed killer. A water main breaks nearby and the weed killer is sucked into the house’s water pipes. What is this called?
Back-siphonage Back-siphonage happens when pressure in the supply drops below atmospheric pressure, creating a partial vacuum. Here the main break pulled the liquid back up the hose. A vacuum breaker on the hose connection would have stopped it.
What is a drainage fixture unit (DFU)?
A measure of a fixture’s probable discharge into the drainage system, used to size drains A drainage fixture unit is a way of rating how much load a fixture puts on the drainage system, allowing for how much it discharges, how fast and how often. You add up the DFUs on a pipe and use the code tables to find the minimum pipe size.
What are water supply fixture units (WSFU) used for?
To size water supply piping from the probable demand of the fixtures Water supply fixture units rate how much water a fixture is likely to demand. You total them for each section of pipe, then use the code’s tables or method, along with pressure and length, to find the pipe size. They’re a separate system from drainage fixture units.
You’re making a solvent-cement joint in PVC pipe. What goes on first, once the pipe is cut and deburred?
Primer, where the code or manufacturer requires it For PVC, you clean and prime the pipe and the inside of the fitting, then apply solvent cement and push the pipe fully into the fitting. Primer softens the surface so the cement can fuse the plastic. Follow the manufacturer’s instructions on the cans, which is what codes refer to.
Why would you use a dielectric union between copper and galvanized steel pipe?
To prevent galvanic corrosion between the two metals When two different metals touch in water, they act like a battery and one of them corrodes faster. A dielectric fitting separates copper from steel with an insulating gasket and sleeve, so current can’t flow between them.
Which is an acceptable way to run the discharge pipe from a water heater’s temperature and pressure (T&P) relief valve?
Full size of the valve outlet, draining by gravity to an approved place The T&P discharge pipe must not be smaller than the valve outlet, must drain by gravity, and must end where hot water won’t hurt anyone or damage the building. It can never have a valve or a cap. If it’s blocked, the relief valve can’t do its job and the tank could fail.
Under federal OSHA rules, at what depth does a trench generally need a protective system, such as sloping, shoring or a trench box?
5 feet OSHA’s excavation rule (29 CFR 1926.652) requires a protective system in trenches 5 feet deep or more, unless the trench is made entirely of stable rock. Shallower trenches still need one if a competent person sees signs of a possible cave-in.
United States · Licensing exam