What is Ultrasonic Flow Meter?
Ultrasonic flow meter is device that measures the volumetric flow rate of fluid flowing through a pipe by measuring the velocity across a known pipe cross sectional area. They are commonly used in household water metering, water processing/treatment, oil and gas, food and beverage industries etc. They operate on either Transit Time or Doppler Shift principle to measure the flow velocity. There are two types of Ultrasonic Flow Meter, namely clamp-on and in-line type ultrasonic flow meter. For clamp-on type, it can be further categorized into permanent type and portable type ultrasonic flow meter. Portable ultrasonic flow meter is used for diagnostic and verification purposes.
Transit Time Method
Transit time Ultrasonic Flow Meter emits an ultrasonic beam across the transducer. The time it takes for the ultrasonic beam to travel between the transducer is measured, this is called the transit time. The speed at which the ultrasonic beam travels through the liquid is accelerated slightly by the velocity of the liquid through the pipe.
When ultrasonic beam is travelling in the opposite direction, the flow of the liquid causes the it to decelerate. The transit time of ultrasonic beam between the transducer is proportional to the velocity of the fluid along the path of the ultrasonic beam. Having measured the velocity of flowing liquid and knowing the cross-sectional area of the pipe, we can compute the flow rate.