There are several distinct types of ultrasonic flow meters that use different techniques to measure flow, including the Transit Time concept and the Doppler Effect principle. The transit time meter is used for clear liquids or liquids having very low levels of undissolved solids.
When the ultrasound wave passes through the liquid, the component of liquid velocity is added to ultrasound velocity. By careful measurement of the Time required by the sound wave to reach the other end of the diameter, one can calculate accurately the water velocity. By knowing the velocity, the volumetric flow rate can be calculated.
Several typical process factors can have a big impact on how well an ultrasonic flow meter works. This means that it is important to install and utilize the meters appropriately in order to reap the benefits of these meters. In this article let’s illustrate these conditions.
An approved flow calibration facility will have its own level of uncertainty for each calibration done before a meter is mounted inline. This uncertainty is considered while calibrating the flow meters. Calibration facilities are regularly audited by authorized agencies to ensure that the facility provides discernible precision and repeatability. The meters calibrated in such facilities can provide reliable and dependable performance.
2. Process conditions
Calibrations are generally conducted at relatively low pressures and temperatures, but these may not accurately replicate the site conditions in industrial applications, leading to increased uncertainty in measurement. For example, changes in temperature or pressure can cause geometric changes in pipelines, which in turn can alter the sensor positions in an Ultrasonic Flow Meter —a key part of the velocity calculation.
3. Installation Effects
An Ultrasonic Flow Meter should ideally be utilized in fully developed, undisturbed flow with a substantial length of straight pipe upstream of the meter because it is prone to a number of installation effects. However, due to space and financial limitations in many applications, ideal circumstances cannot be achieved. As a result, flow disturbances are caused by pipework fixtures such as bends and valves. Such disturbances can result in swirl and asymmetry in the flow profile, which can lead to mistakes in the calculation of flow.
Although there is a fundamental measurement uncertainty present in any measurement device, the overall impact depends heavily on the geometry of the route site and the Ultrasonic Flow Meter design.
5. Usage of flow meters: Rules and Protocols
If the meters are used properly, the impact of process conditions can be successfully minimized. Proper meter specification, calibration, installation, and maintenance are the first steps in this process. To ensure that the meters perform at their best, it is crucial to adhere to best practice rules and protocols.
Our team of experts is always at your service to guide you through the correct installation and maintenance of flow meters.