Non invasive water flow meter

Non invasive water flow meter development

Non invasive water flow meter is using ultrasonic flow measurement technology; the flow meter transducers are often clamp on types without intrusive to the water pipelines, we often see portable ultrasonic flow meter, handheld ultrasonic flow meter or wall mount water flow meters with non invasive flow sensor to take water flow measurement.

Ultrasonic flowmeter technology has emerged in the market since 1970. At the beginning, it was mainly based on Doppler flow meter. However, in the early stage, Non invasive water flow meter technology was applied in many inappropriate applications which resulting in poor measurement results. Years later, some more successful applications have been promoted, and ultrasonic water flow measurement with non invasive technology has gradually been recognized by users. At the same time, the ability of the electronic processing unit of ultrasonic flowmeters has been improved in the past few decades with the improvement of the technical level of the electronic industry. With continuous development, these improvements not only expand the application field of Doppler flowmeters, but also make the time transit ultrasonic flowmeter applied to a variety of applications, and can obtain higher accuracy, thus making the non Invasive ultrasonic flowmeter technology get more used.

Since 1990, many oil and gas companies and flow calibration stations have accumulated a large amount of practical data, thus completing the first research report on the measurement of natural gas by ultrasonic flowmeters in 1996, which is the 1998 AGA 9 important part of the report. Since then, ultrasonic flowmeters have been widely developed in the field of natural gas metering. In 2005, also based on a large number of practical data, the API 5.8 standard for measuring liquid hydrocarbons by liquid ultrasonic flowmeter was officially promulgated, which effectively promoted the application of liquid ultrasonic flowmeter in petroleum and its products.
At present, the number of ultrasonic flowmeters is applied globally at a rate of more than 10% per year. China is the fastest growing country, and the oil and gas industry is the largest application industry.

Non invasive water flow meter principle

There are two common ultrasonic flowmeter technologies on the market today: the transit time flow meter and the Doppler flow meter. Although the Non Intrusive Flow Meters with transit time method was invented later, it is widely used and can achieve higher accuracy for water measurement. Although the application of Doppler technology has many limitations, it also has its unique application for waste water or dirty water measurement.

Transit time flow meter with non invasive water flow sensor

The transit time flow meter method refers to the technique of determining the water velocity in the pipeline by measuring the time between the two transducers when the ultrasonic pulse is flowing forward and backward. Each transducer acts as a transmitter and then a receiver. Transit time flow meters are mainly for clean water, tap water, ground water, fire fighting water.,etc, not suitable for dirty water or sewage or effluent.
Under the condition that the water fills the pipe and is stationary, the time of the ultrasonic pulse to and from the transducer is theoretically the same. Because in a static fluid, the speed of ultrasonic sound propagating in different directions is constant. If water flows through a pipe, the ultrasonic pulses travel faster downstream than upstream, and the time difference between the two is proportional to the velocity of the water in the pipe. Both mono and multi-channel ultrasonic flowmeters can be used to measure water flow rates, but multi-channel ultrasonic flowmeters measure more accurately because it obtains flow rate information from different locations in the water profile, thus closer to the actual flow rate situation. The flow velocity is calculated from the travel time over a fixed distance and is not affected by factors such as water temperature, pressure and fluid composition.
Ultrasonic water flow meters have very high accuracy over a very wide flow range without pressure loss in the pipeline. Because there are no moving parts, ultrasonic flow meters are very stable performance as non Intrusive Flow Meters .In general, non invasive water flow meters have the following main advantages over other types of flowmeters: no moving parts flow meters, non-contact flow meters, no pressure loss; wide turndown ratio; bidirectional metering; no need Periodic maintenance; simple plumbing work required for installation; stable and long life.

Clamp on ultrasonic water flow meter

The ultrasonic flowmeters of the Doppler method and the time transmission method have a clamp-on installation; it can be clamp on water flow meters. Non Invasive flow meters do not penetrate the pipe wall and their probes do not come into contact with water. This non  Intrusive flowmeter has advantages in measuring corrosive fluids, but its accuracy is low and cannot meet the requirements of high accuracy. The clamp-on flowmeter needs to strictly comply with the following operations: the material of the pipe to be measured must be suitable for sound wave transmission; the mounting surface must be clean and clean; the probe must be acoustically coupled to the outside of the pipe (usually grease or epoxy is used); the inner wall of the pipe to be measured must be free of substances capable of absorbing sound waves. For example, flow meter manufacturers provide different ways to install clamp on flowmeters to position the probe. Some manufacturers attach the probe assembly to the outer wall of the pipeline by means of alignment rail, strap, link chains or surface mount to mount the entire module to the pipe. The speed of sound at which a sound wave travels is determined by the material it passes through, and the resulting angle of refraction varies widely. Because both the pipe and the water can produce refraction angles, it is very difficult to position the probe accurately. Additionally, probe positioning that works for one fluid will not work for other fluids due to changes in the angle of refraction.
When accurate probe positioning is complete, the probe must be acoustically coupled to the outer pipe wall with grease or epoxy. Rough coupling surfaces can cause the probe to detach from the pipe wall, affecting pulse transmission and reception between probes. For custody transfer applications, clamp-on ultrasonic flow meters do not have the required accuracy and stability.

Specifications of non invasive water flow meter

• Non invasive water flow meter can be made wall mount invasive water flow meter or portable type water flow meter or handheld water flow meters;
• Forward and reverse water flow can be measured and recorded on the data by non Intrusive Flow meters.
• A variety of communication protocols is available by Non Invasive flow meter transmitters, such as 4-20mA, pulse, relay, RS485, Modbus. Flow meter can transmit data to PC or cloud through the protocol to realize the Internet of Things. The communication protocol is suitable for different environmental conditions.
• Flow transmitter has built-in data logger to save water measurement data and the data can be exported to computer. The inspection pipeline data can be exported in the maintenance inspection. The data includes time, water flow rate, water total flow, forward and reverse water flow, and the measurement interval time can be set, which is suitable for pipeline inspection work water flow monitor work.
• Different ways to install non invasive flow ultrasonic probe, such as chain link, alignment rail or strap. Non contact flow meters to have zero pressure loss.
• Non invasive water flow meters are with clamp on transducers to have no damage to the water pipeline and will not lead to water pipeline leakage.
• Water pipe line size from DN32 to DN2000, normal request size is 1 inch non invasive water flow meter, 2”, 3” 4 inch, DN100,6 inch ultrasonic flow sensor, 8 inch, 10” , 12inch or DN300 clamp on flow meters
• Water Velocity range: ±0.01m/s~±12.0m/s