A portable ultrasonic flow meter is a flow measurement device designed based on the propagation characteristics of ultrasonic waves. It can measure the flow rate and heat of various single, homogeneous liquids that can conduct ultrasonic waves. Employing a non-contact measurement method, it does not require penetration into the pipe and can complete the measurement without affecting fluid flow. It is widely used for measuring fluids such as water, seawater, industrial wastewater, acids, alkalis, and oils, and plays an important role in energy consumption measurement in industries such as refrigeration, heating, heat exchangers, and boilers.
The device mainly consists of a main unit, sensors, a temperature sensor, and various accessories. The main unit, as the core control unit, is equipped with an LCD display and an operation keyboard, enabling parameter setting, data display, and processing. It can be equipped with two pairs of sensors, selected according to pipe diameter and temperature requirements. For example, small sensors are suitable for pipes with diameters from DN15 to 40 mm, while high-temperature sensors can withstand temperatures from -40°C to 180°C. The temperature sensor is used to collect fluid temperature during energy measurement, which, combined with flow data, completes the heat calculation. The main features of the equipment include: high measurement accuracy, with flow measurement error not exceeding ±1% and heat measurement error not exceeding ±2%; wide measurement range, covering pipes with diameters from 15mm to 1200mm; compatibility with various pipe materials, such as steel, stainless steel, cast iron, PVC, copper, and aluminum; support for Chinese and English language display; and comprehensive data storage and transmission capabilities, allowing data recording via SD card and network communication via RS485 interface. Its measurement principle is based on the propagation characteristics of ultrasound in fluids. When an ultrasonic beam propagates in a liquid, the liquid flow causes a slight change in propagation time, and this change is proportional to the liquid flow velocity. At zero flow, the upstream and downstream sensors transmit and receive sound waves at the same time; when the liquid is flowing, the propagation time of the sound wave in the counter-current direction is longer than that in the downstream direction. By calculating the time difference between the two and combining it with pipe parameters, the fluid velocity and flow rate can be derived.
During operation, the following conditions must be met: The pipeline must be filled with fluid; prioritize pipelines with vertically upward or obliquely upward flow, and avoid installing on pipelines at the highest point of the piping system or those with vertically downward flow; ensure stable fluid flow, and keep away from pump outlets, partially open valves, and other locations prone to turbulence. If this cannot be avoided, ensure that the upstream straight pipe section is at least 10D (D is the pipe's outer diameter) and the downstream is at least 5D; avoid scaling on the inner wall of the pipeline as much as possible; if scaling exists, clean it or use the Z-method for measurement; the fluid temperature must be within the sensor's tolerance range and away from sources of interference such as frequency converters and high-voltage lines. Before measurement, pipeline parameters must be entered into the host computer, including pipe outer diameter, wall thickness, material, lining (if any), fluid type, sensor type, and installation method. After parameter input, the host computer will calculate the sensor installation distance, and the operator must install the sensor according to this distance.
