Patent ID: 6826965
Filing Date: 2004-12-07
Classification: G01F

Abstract:
An ultrasonic measurement system for determining flow of a gas or low density fluid in a conduit, such system comprising:a first clamp-on transmitter receiver pair configured to define a first ultrasonic signal path across fluid flowing in the conduit and to generate a first tag-modulated output signal; a second clamp-on transmitter receiver pair configured and mounted to define a second ultrasonic signal path anti-parallel to the first ultrasonic signal path and across fluid flowing in the conduit, said second ultrasonic signal path spaced a fixed distance from said first ultrasonic signal path, said second clamp-on transmitter receiver pair further configured to generate a second tag-modulated output signal; and a processor configured to correlate said first tag-modulated output signal of said first pair with said second tag-modulated output signal of said second pair to determine a time interval representative of flow.