In the building drainage system, PVC pipe fittings are like invisible "pipe connectors", connecting straight pipes in series to form a complete drainage network, ensuring that sewage and wastewater can flow smoothly "to" septic tanks or municipal pipe networks. From floor drain connections in household bathrooms to risers in shopping malls, the choice and use of PVC pipe fittings directly affect the stability of the drainage system - if you use the wrong elbow, it may cause water flow blockage; if you install one less trap, the odor of the sewer can fill the whole room. Today, organize the common pipe fittings in PVC drainage systems into a "practical list", from the most basic elbow to the multi-functional tee, and explain their functions and usage one by one.

Let's start with the elbow - this is the "key piece" to change the direction of the pipe, and it is used at almost every turn. The most common are 90-degree and 45-degree elbows: 90-degree elbows are mostly used in scenarios that require right-angle turns, such as when the drain pipe of the toilet (usually 110mm diameter) needs to be connected vertically to the main riser, use it just right; 45-degree elbows are more "gentle", suitable for adjusting the slope of the pipe or turning slowly. For example, when the drain pipe (50mm or 75mm) of the kitchen sink needs to be connected to the main pipe, using a 45-degree elbow can reduce the resistance of water flow and avoid the accumulation of vegetable leaves and residue. There is also an elbow with an inspection port, and an openable cover is reserved on the side of the elbow. If the pipe is blocked later, it can be cleaned directly without removing the pipe, which is very suitable for installing in a position that is easy to block.

is followed by a tee - responsible for the "diversion and confluence" of the pipeline. The regular tee is three interfaces with the same diameter, such as three 110mm interfaces, which are often used for pipe branches of the same diameter. For example, the main riser in the bathroom of a shopping mall needs to separate two branches to different squatting toilets; the different diameter tee is "one large and two small" or "one main and two pairs". For example, the main interface is 110mm, and the two sides are 75mm. It is suitable for the main riser to separate the branch pipe to connect to the sink, floor drain and other small-diameter pipes. Some tee also have a "oblique port design". When the water flow comes in from the main pipe, it can flow along the oblique port to the branch pipe, reducing eddy current and impact, and it is not easy to block.

Then there is the direct (pipe hoop) - the simplest but most commonly used "extension". Its function is to connect two straight pipes of the same diameter together. For example, when the drain pipe is not long enough during decoration, it can be extended by directly putting it on the interface of the two pipes and sealing it with glue. The direct quality is very important. If the interface is not flat, it is easy to leak glue and cause water leakage, so when choosing, you should touch the inside of the interface to be smooth and free of burrs.

The variable diameter (size and small head) is a "transition piece" that connects different pipe diameters. For example, the main riser is 110mm. To connect the 75mm branch pipe to the balcony washing machine, you have to use 110mm to 75mm variable diameter. It allows the water flow to transition smoothly from the large pipe to the small pipe, avoiding "water hammer" (the sound of water impacting the pipe wall) caused by the sudden reduction of the pipe diameter, and can also reduce the probability of debris getting stuck at the interface.

plug (pipe plug) is "the little expert of pipe sealing". It is inevitable that there are reserved pipe openings that are not used for the time being during decoration. For example, the spare floor drain in the bathroom must be sealed with a plug - the threaded plug can be unscrewed and is suitable for the position that may be used in the future; the adhesive plug is disposable, glued and firmly glued, suitable for permanently closed pipe openings. If the plug is not selected correctly, reserve the mouth to leak odor or enter debris, which will be very troublesome to clean up later.

Inspection port/cleaning port is the "maintenance window" of the drainage system. The inspection port is generally installed on the riser, one every other floor, and the lid can be opened to see the inside of the pipe, which is convenient for checking whether there is blockage; the cleaning port is installed at the end of the horizontal pipe, such as the end of the drain pipe on the bathroom floor. If the pipe is blocked, unscrew the cleaning port and use a dredger to poke it, without removing the floor. Although these two accessories are not conspicuous, they can save a lot of effort at critical moments, and do not save it when decorating.

Finally, it is said that the trap - the "core weapon" of deodorant. Its principle is to leave a "water seal" in the pipe, like a "water gate", to prevent the odor of the sewer from rising up. The S-type trap is suitable for installing under the floor drain, because it has a large curvature, which can store more water and has a good deodorant effect. The P-type trap is suitable for installing on the drain pipe of the sink and vegetable sink, because it is more compact and does not take up space. If the floor drain in the home is unpleasant, nine times out of ten, the trap is not installed or the water in the trap is dry (such as a house that has not been lived for a long time).

When choosing PVC drainage pipe fittings, there are a few points to keep in mind: first look at the material, choose PVC-U material that meets the GB/T 5836.2 standard, which is hard to the touch and has no pungent smell; second pair of specifications, the diameter of the pipe fittings should be the same as the pipe, such as 110mm pipes with 110mm elbows, don't buy the wrong one; third check the appearance, the surface should be smooth, no cracks, bubbles or depressions, and the wall thickness at the interface should be uniform, otherwise the pressure will be high and easy to crack; fourth look at the pressure level, the drainage system generally uses "low pressure pipe fittings" (to withstand the pressure of 0.6MPa), but high-rise residential (such as more than 30 floors) is best to choose "medium pressure pipe fittings", which has better pressure resistance.

In fact, there are not many "doorways" for PVC drain pipe fittings, but every small accessory has its "responsibilities" - the elbow is responsible for turning, the tee is responsible for diverting flow, and the trap is responsible for deodorant. If any one is missing, the drainage system may have problems. For example, when decorating, in order to save space, the trap was removed, and the smell of the drain ran into the room; or the inferior elbow was used, and it cracked after two years, and the water leaked downstairs, losing thousands of dollars to the neighbors.

To sum up, the selection logic of PVC drain pipe fittings is very simple: choose the type according to the needs, choose the specifications according to the regulations, and choose the brand according to the quality (but the specific brand is not mentioned here). Save this list and compare it when decorating or repairing. There is basically no mistake. After all, the "security" of the drainage system is hidden in these small pipe fittings.