PVC corner fittings are designed to link two or more lengths of PVC pipe together in a constricted space, such as under a cabinet or in a wall. Most PVC corner fittings can be used for construction and plumbing alike, but some fittings were created specifically for the plumbing industry to meet NSF standards. NSF is the regulatory body that determines safety and performance standards for plumbing system components. Past debate about potential health risks of PVC has resurfaced with the green movement.
90-Degree Bends and 45-Degree Bends
The 90-degree bends turn a run of PVC around a tight corner. They can be 2-way, 3-way, 4-way or 5-way connections. Three-, 4- and 5-way connectors are essential for three-dimensional structures. 3-way connectors join three runs of pipe at the corner of a cube. 4-way connectors allow a horizontal or vertical run to continue while a perpendicular run begins. 5-way connectors bridge vertical runs with multiple horizontal runs. They allow a central support post to add strength to a central connection to ensure that added weight and stress from multidirectional pressures do not cause a joint to fail. 45-degree bends create a smoother, more gradual run. They are good for pentagonal, hexagonal and octagonal construction, such as gazebo roofs, bench frames, greenhouse roofs and shade structures. Both 90-degree and 45-degree corner connections have either a slip or a threaded connection. The connection is considered female if the pipe will slip inside it, or male if it will slide or screw into the pipe. Pipe connections can be threaded inside, which is female, or threaded outside, which is male.
Long sweeps are gently angled corner connectors. They are used to change direction from horizontal to vertical in a waste drain or vent. The long, gradual change in direction prevents blockages.
Caps and Couplings
Cleanout caps are threaded to fit inside your pipe at a corner. Cleanout caps allow access to remove clogs and debris without taking your entire drain system apart. Couplings are short connectors that permit two pieces of pipe to be joined when you do not want to create a turn. They can be used to continue a straight run of pipe while another pipe branches off at an angle.
Although not necessarily a corner, male/female adaptors are sometimes needed in order to create a corner. If two runs of pipe come together with the same end type, no connection can be made. Adaptors can be male at both ends, female at both ends, or male at one end and female at the other. Three-ways can have all three male or female, 2 male and one female or two female and one male connection. Four-ways can have all male connections, all female, one male and three female, one female and three male, or two of each.
Sanitary tees are designed so that waste will flow through in a vertical run while accepting horizontal intakes without clogging. This allows second-story wastes to flow into outgoing sanitary sewers or septic systems without impeding first-story waste flow. Branches curve down to meet a drain, or up if the tee is part of a vent system. Sanitary tees can have expansion or reduction connections as well as matching connections. Connecting too many lines into one drain can lead to clogs and backflows. Ideally, each drain should be a continuous vertical run with no more than two inputs. Sinks, toilets and laundry drains should each have a separate drain.
PVC wyes are used when a sewer or vent connection is angled up or down instead of completely vertical. According to Merle Henkenius of Popular Mechanics, "A tee can carry water only when it's used vertically, while a wye can be used on its side or back, provided the line feeding it is vented." Wyes are often used to connect first-floor toilet outputs to basement sewer lines.