Publish Time: 2022-07-15 Origin: Site
Today, ultrasonic liquid level measurement technology is a very representative type of echo ranging technology. Since the ultrasonic level gauge uses a non-contact measurement method to monitor the medium, it has good applicability to the measurement of liquid and solid levels. However, in practical applications, ultrasonic measurement technology will also encounter problems. The engineer of the R&D Department of Shenzhen Jiwei Automation Technology Co., Ltd. Common problems and solutions in practical applications.
The structure of the ultrasonic level gauge is simple, and the transducer is also called the probe of the ultrasonic level gauge, which is the most important part of the ultrasonic level gauge. The ultrasonic level gauge emits ultrasonic pulses from the probe, and when the pulses touch the medium interface, they are reflected back and received by the probe. According to the time from transmitting to receiving the pulse and the speed of sound in the medium, the distance between the probe and the medium can be obtained to determine the liquid level.
Ultrasonic liquid level gauge is an industrial instrument designed and developed for measuring liquid level by taking advantage of the good directionality of ultrasonic waves, strong penetrating ability, easy to obtain concentrated sound energy, and long transmission distance in water. Ultrasonic level gauges have been widely used in medicine, industry, agriculture and other fields.
Liquid level measurement is a problem often encountered in the industry. Ultrasonic positioning technology has many advantages. It can not only determine the position and continuously measure the position, but also can easily provide the signals required for telemetry or remote control. Compared with radioactive positioning technology, ultrasonic technology does not require protection. Compared with laser ranging technology, it has the advantages of simplicity and economy. At the same time, ultrasonic technology generally does not require moving parts, so it is relatively convenient in installation and maintenance.
Ultrasonic level gauge can be widely used in petroleum, mining, power plants, chemical plants, water treatment plants, sewage treatment stations, agricultural water, environmental monitoring, food (wine industry, beverage industry, additives, edible oil, dairy products), flood control Flood control, hydrological monitoring, open channels, spatial positioning and many other industries.
Ultrasonic level gauge is widely used in the level measurement of chemical, water treatment, water conservancy, food, grain and other industries. It has the characteristics of safety, cleanliness, high precision, long life, stable and reliable, convenient installation and maintenance, and simple reading. The product adopts two-wire, three-wire or four-wire technology, and the power supply circuit and the signal output circuit are independent. When using DC 24v power supply, a 3-core cable can be used, and the negative end of the power supply and the negative end of the signal output share one core When using AC 220v power supply, or when using DC 24v power supply, when the power supply circuit and the signal output circuit are required to be completely isolated, a 4-core cable should be used. DC or AC power supply, with 4~20mADC, high and low switch output.
1. Scope and size
The size of the object to be detected by the liquid level gauge directly affects the maximum range of the ultrasonic sensor. The sensor must detect a certain sound level before it can output. Large parts reflect most of the sound to the ultrasonic sensor so that the sensor can detect the part at its maximum sensing distance. Small parts reflect only a small fraction of the sound, resulting in a greatly reduced sensing range.
The object to be detected
The ideal object for ultrasonic detection of a level gauge should be large, flat, dense, and perpendicular to the front of the transducer. The most difficult objects to detect are those that are small and made of sound-absorbing material such as foam rubber, or that are at an angle to the transducer. Some difficult-to-detect objects can be detected by having the sensor detect the background surface and then react to the detection target object between the sensor and the background.
Liquid detection is easy if the liquid level is stationary and perpendicular to the sensor surface. If the liquid level fluctuates greatly, the response time of the sensor can be extended to average the fluctuations for a more consistent reading. However, ultrasonic level gauges cannot yet detect liquids that have a foamy surface, because foam can deflect the direction of sound propagation.
3. Vibration
Whether it is the vibration of the sensor itself or the vibration of nearby machinery, it can affect the degree when measuring the distance. Rubber anti-vibration devices can be used to reduce these problems when installing the ultrasonic level meter. Rails are also sometimes used to eliminate or greatly reduce component vibration.
4. Attenuation
The sensor is also designed with temperature compensation to accommodate slow changes in ambient temperature. However, it cannot accommodate temperature gradients or rapid changes in ambient temperature.
5. False test results
Objects near the level gauge, such as rails or rods, may reflect sound waves. To accurately detect target objects, the effects of nearby sound-reflecting surfaces must be reduced or eliminated. In order to avoid false detection of nearby objects, the ultrasonic level gauges are equipped with LED displays to indicate the operator during installation to ensure the sensor is installed correctly and reduce the risk of false detection.
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