Elbow mainly available in two standard types 90 ° and 45 °. However, it Can be cut to any other degree. Elbows are available in two radius types, Short radius (1D) and Long radius (1.5D).
A street elbow (sometimes called a street ell or service ell) is a type of plumbing or piping fitting intended to join a piece of pipe and another fitting at an angle. The difference between a street elbow and a regular elbow is the gender of its two connections.
Few people ever wonder why their elbows are called elbows, but there is a reason. The word breaks into two parts el and bow. Inside your forearm are two bones called the radius and the ulna. Thus the literal meaning of the word elbow is arm bend.