LR
LR is an abbreviation of Long Radius Elbow.
Elbows are split into two groups which define the distance over which they change direction; the
center line of one end to the opposite face.
This is known as the "center to face" distance
and is equivalent to the radius through which the elbow is bent.
The center to face distance for a Long Radius elbow, abbreviated LR always is 1.1/2 x Nominal Pipe
Size (1.1/2D), while the center to face distance for a Short Radius elbow, abbreviated SR even is
to nominal pipe size.
