Ultrasonic Flow Meter – Vetrix US Series

Dpstar is one of Malaysia’s leading experts in flow meter solutions. Since the 90s, we have built a reputation for outstanding customer service and unrivaled expertise within our industry. An ultrasonic flow meter can be defined as, a meter that is used to measure liquid velocity with ultrasound to analyze the volume of liquid flow. This type of flow meter is ideal for the applications wherever chemical compatibility, low maintenance, and low-pressure drop are required. Using ultrasonic waves, the flow volume of a wide variety of gases and liquids can be measured reliably with the independent of electrical conductivity, pressure, temperature or viscosity. Clamp-on ultrasonic sensors, are installed on the outer wall of the pipe and also enable temporary measurements or a retrofitting.

Dpstar Clamp-On Ultrasonic flow meters are designed for applications where a customer is unwilling or unable to cut into the process measurement line to install an in-line flowmeter. Clamp-On Ultrasonic flow meter operates using transit time measurement. By measuring the time, it takes an ultrasonic signal to travel a known distance with the flow stream and another signal travelling against the flow stream, it determines the velocity of the fluid being measured. Clamp-On Ultrasonic flow meters can be installed without having to stop the process or cut into the pipe line. It is ideal for process measurement in applications where users previously had not installed an in-line flowmeter, large line sizes and exotic materials are required for in-line measurement technologies.

Working Principle

The ultrasonic flowmeter utilizes the propagation time of the ultrasonic signal in the fluid. A pair of transducers is installed on the outer surface of the pipe, as shown in figure 1. Each transducer works alternatively as both transmitter and receiver of ultrasonic signals. When the ultrasonic signal is transmitted toward the upstream side against the flow direction, more propagation time is required (T1). Next, when it is transmitted toward the downstream side with the flow direction, the propagation time is less (T2). The signal will be delayed and speeded up accordingly by the moving fluid. The different between T1 and T2 is proportional to the flow velocity, and the volumetric flow rate can be computed by multiplying the cross-sectional area with the flow velocity. Simplify by the equation Q = VA, where; Q = Volumetric Flow Rate, V= Flow Velocity, A= Cross-sectional Area.

Figure 1: Ultrasonic Flowmeter Installation (Z-Method)

How it works

Ultrasonic flowmeters use sound waves to determine the velocity of a fluid flowing in a pipe. At no flow conditions, the frequencies of an ultrasonic wave transmitted into a pipe and its reflections from the fluid are the same. Under flowing conditions, the frequency of the reflected wave is different due to the Doppler effect. When the fluid moves faster, the frequency shift increases linearly. The transmitter processes signals from the transmitted wave and its reflections to determine the flow rate.

Transit time ultrasonic flowmeters send and receive ultrasonic waves between transducers in both the upstream and downstream directions in the pipe. At no flow conditions, it takes the same time to travel upstream and downstream between the transducers. Under flowing conditions, the upstream wave will travel slower and take more time than the (faster) downstream wave. When the fluid moves faster, the difference between the upstream and downstream times increases. The transmitter processes upstream and downstream times to determine the flow rate. They represent about 12% of all flowmeters sold.

Benefits of Our Ultrasonic Technology

• Cover wide range of pipe size from DN15 to DN6000 with 3 pairs of sensors
• Ultrasonic flowmeters can measure the flow of conductive or non-conductive liquid.
• Minimum pipework disturbance (No cutting or welding required).
• Ultrasonic flowmeter has no moving part; therefore, maintenance cost is very low.

Advantages of Ultrasonic Flowmeter

• Ultrasonic flowmeters can measure the flow of conductive or non-conductive liquid.
• For the measurement of low flow rates, the ultrasonic flowmeter is a better option compared to any other types of flowmeters.
• Minimum pipework disturbance (No cutting or welding required).
• Ultrasonic flowmeter has no moving part; therefore, maintenance cost is very low.

Applications

Nowadays, the ultrasonic flowmeter is used in many different industries. Our main customer markets are the food, beverage, pharmaceutical, analytics and chemical markets. In addition, these meters are used in wastewater and dirty liquid applications and used wherever chemical compatibility, less maintenance, and low-pressure drop are required.