Often, when assembling or replacing the sewage system, customers are asked to purchase material so as not to bother with trips to the store and the purchase of fittings and pipes. What is really good, there are no "smut" on the agreement of the purchase of the necessary fittings for high-quality drainage assembly.
Several times, after assembling the sewage system, scrupulous customers were interested in why the pipe was not allowed here diagonally, with a large angle, thereby saving on the pipe. Or why, instead of a corner of 90 degrees, two of 45 are used, so it's more expensive. If the first question is already answered here in this article: Critical rules when assembling sewers, we figure out which angle must be observed.
We will find out now why to use a smooth angle on the sewer drain. For example, I prepared illustrations.
Let's say we have a bunch of fittings, it is required to collect a drain for the sink and washing machine.
A person ignorant of some physical processes will collect it like this:
What, in principle, is already wrong, imagine how the drained liquid will behave:
A sharp transition of the liquid flow from a vertical position to a horizontal one, at a right angle, leads to extinguishing of the energy of the liquid, therefore, to a slowdown in drainage. If the fittings have few fastenings, the connections can loosen, resulting in leaks. The 90 degree tee adds another problem. Part of the liquid hitting a straight section spreads in different directions or collides with a counter flow, which is very undesirable, especially if the liquid has a fatty base (from the shell).
How to properly assemble the sewage system?
In the illustrations above, you can observe a properly assembled drain, based on 45 degree angles. Thus, it is possible to avoid the loss of energy of the liquid and parasitic flows inside the pipe.