See image - [1]

# Street Elbows

Named after - the 'street' is where men and women meet. Refers to one end being male, one female. This does not refer to gentleness of bend.

Tightest bend is vent elbow - for use in venting only, not water.

Then is 1/4 turn elbow. Same as 1/4 bend.

Then is short sweep. Not! Short sweep appears to be just a qualitative description referring to the 1/4 bend.

Then is long sweep.

# IRC Table 706.3

• What is the difference between 'short sweep' and 'long sweep' if '1/4 bend' is also there? [2]

# Understanding Direction Change and Flow

[https://www.quora.com/When-plumbing-drains-when-should-you-use-a-90-degree-long-sweep-versus-a-regular-90-degree-elbow quora has a decent explanation - of why quarter turns can be used going from horizontal to vertical, and why sweeps should be used going from vertical to horizontal - based on a water park analogy -

The best way to remember when to use either fitting is to imagine you're building a water park ride. You would want the tops of the drops to be more sudden so that you know the limited amount of water wont drain away too fast and leave the “rider" stuck half way over the edge. On the other hand, you would want there to be a comfortable landing that allows all “riders" to maintain a nice flow and not cause a bottleneck of traffic waiting for them all to be julted by the sudden change of direction and make their way around the bend. Same thing horizontally. Imagine running down a corridor and having to make an immediate right or left turn at the end. You would not be able to maintain the same speed in that situation. It would be better if the corridor made a more gradual turn.

Also:

If water is speeding up as it turns the corner (usually going from horizontal to vertical), use a short sweep. If water is slowing down (usually from vertical to horizontal), use a long sweep.

Also:

Having been a plumber for most of my adult life I feel qualified to answer your question. you can never go wrong if you think, ‘long sweep up and 1/4 bend (regular 90) down. And add long sweep to horizontal 90 degree change of direction. Never use regular 90 on the horizontal.