Transittimemätare

Transittimätare, often translated as transit time meter, is a device used to measure the time it takes for a fluid to flow through a defined section of pipe. This time measurement is then used to calculate the fluid's velocity and, consequently, its flow rate. The principle behind transit time meters relies on the Doppler effect or the time difference between two ultrasonic signals. In the Doppler-based transit time meter, an ultrasonic transmitter emits a signal that is reflected by particles or bubbles within the fluid. The frequency of the reflected signal is shifted due to the motion of these reflectors. By measuring this frequency shift, the velocity of the fluid can be determined. In contrast, a transit time meter that measures the time difference sends ultrasonic pulses in both the upstream and downstream directions. The pulse traveling with the flow will arrive slightly sooner than the pulse traveling against the flow. The difference in these travel times is directly proportional to the fluid's velocity.

Transit time meters are non-intrusive, meaning they do not require any part of the device to be inserted into the flow path. This is typically achieved by clamping transducers onto the exterior of the pipe. This non-invasive nature makes them ideal for applications where introducing obstructions is undesirable or impossible, such as in the food and beverage industry, water treatment, or for measuring corrosive or high-purity fluids. They are known for their accuracy, wide range of applications, and ability to handle various fluid types, including clean liquids, slurries, and gases. The accuracy can be influenced by factors such as fluid cleanliness, pipe material, and the presence of significant turbulence.