The screw connection is a widely used detachable fixed connection, which has the advantages of simple structure, reliable connection, and convenient assembly and disassembly. Thread is a key part of thread coupling and screw drive, let us take a look at the classification of thread.

According to the tooth shape, it can be divided into triangle, trapezoid, rectangle, zigzag and arc thread;

According to the thread rotation direction, it can be divided into left-handed and right-handed;

According to the number of spiral lines, it can be divided into single line and multi-line;

According to the shape of the thread matrix, it can be divided into cylinder and cone.

For threaded connections of radar level transmitters, there are two most common types: G 1 1 / 2A thread; NPT thread.