The Development History of Ultrasonic Heat Meters

1. Ultrasonic waves are not the latest high-tech technology that has emerged. They were used by the Allies in their operations against Germany as early as World War II to detect submarines on the seabed. Compared to others, Wiegand technology originated in the United States in 1974, and non-magnetic detection technology originated in Germany in 1987, and is widely used in civilian applications, especially in the medical field.
2Ultrasonic heat meterAfraid of impurities in water, as impurities in water can offset the incident angle of ultrasonic waves, affecting accurate measurement. So now promoting ultrasonic heat meters is not afraidBlockage, this is beyond reproach because it is close to a straight pipe state, but impurities in the water can affect the ultrasonic transducer, which the manufacturer did not mention at all, misleading users. A real problem is that impurities in the water affect the measurement.
3. Ultrasonic heat meters are sensitive to bubbles in water because the propagation speed of ultrasonic waves in water is around 1500 meters per second, while in air it is 330 meters per second. After all, our heating network is not a manufacturer's testing platform, and we use pure water without bubbles. Heating networks cannot be free of impurities, bubbles, etc., and there may be measurement errors close to 5 times based on the propagation speed in water and air; Even if there are special requirements during installation, they cannot be avoided.
4. Ultrasonic transducers (i.e. ultrasonic generators and receivers) require high precision, consisting of piezoelectric materials such as aluminum zirconate titanate and acoustic wedges made of organic glass with a transmission word count close to 1. They require high strength, strong toughness, and aging resistance. At present, the price of the previous pair of imported transducers is around 200 yuan, which is too high, and the quality of domestically produced products with low prices is not guaranteed, making it incomparable to the quality of imported products.
5. Ultrasonic waves are used on heat meters to measure flow using the "differential method". The specific principle is that when ultrasonic waves flow together with water in water, a time is generated, and compared with the normal speed, a time difference is generated. The time difference is used to calculate the flow rate of water, and then the flow rate is multiplied by the pipe diameter to obtain the flow rate. So it's called the 'differential method'. This method requires strict timing control. Generally, the propagation speed of ultrasound in water is 1500 meters per second, and the timing control circuit needs to be calculated based on the period of the microcontroller, which is usually 10-12 seconds. Millisecond level cannot be achieved, and slight deviation can affect the measurement.
6. Ultrasonic heat meters need to undergo a "speed increase" treatment on the transducer components, that is, to increase the speed of the water flow, in order to make the ultrasonic speed more consistent at low flow rates. What can be done about this? Only the diameter of the transducer part can be reduced, that is, "reduced diameter". Therefore, some ultrasonic heat meters with a nominal diameter of DN20 now have a "reduced diameter" part that is less than the diameter of DN15. Increased pressure loss.
7. The operation and maintenance costs of ultrasonic heat meters are too high. Due to the high power consumption of their ultrasonic transducers, the lifespan of the built-in battery is shortened. If the transducer is damaged, the entire flow meter needs to be replaced, which is too expensive. Additionally, the transducer is very sensitive to vibration and is prone to detachment, making it a vulnerable component and difficult to maintain.
Summary: Although ultrasonic heat meters claim to be not afraid of blockages or impurities in water, and impurities in water have no effect on the cavity, they affect the ultrasonic waves generated by the ultrasonic transducer. Therefore, we should not only see one side of the ultrasonic heat meter, but also the other side for evaluation.