Detecting object passing inside pipe esp. tool joints in boring tube - by measuring the time taken for ultrasonic impulses to rebound across the tube

摘要

The passage or variation in section of an object inside a tube is carried out by timing ultrasonic impulses. Transmitter-receiver couples are positioned inside the tube. Transmit impulses to rebound from the opposite wall and receive the echoes. These transmitters can be connected to separate impulse generators or to the same generator. If connected separately the time difference between transmission and receipt of echo for each couple is taken. When connected to the same generator the difference in time for the impulses is measured, a non-zero difference indicating an object in front of one. Used esp. in the detection of the passage of tool joints in boring tubes. Only a low energy supply is needed.