【正文】 quid level meter and radar material level meter (1) ultrasonic liquid level meter Material level measurement process, the ultrasonic signal, issued by the ultrasonic probe, the liquid or solid material surface after launch back, by the same sensor receiving, ultrasonic measurement of the whole running time, so as to realize the measurement of material level, 2 acoustic velocity transmission of the ultrasonic pulse, from transmitting to receiving to ultrasonic pulse need time interval and the transducer to the surface of the measured medium is proportional to the distance. Emit ultrasonic level meter pulse, not the echo of detection at the same time. Due to the launch of the ultrasonic pulse width has a certain time, and after launch the ultrasonic sensor and aftershocks, during cannot detect the echo, so from the start down the surface of the probe a short distance can39。t use ultrasonic liquid level meter. (2) radar material level meter Radar level gauge USES launch reflection receive work mode. Radar level meter antenna emit electromagic wave, the wave reflected by the measured object surface, again by the antenna, the electromagic wave from transmitting to receiving time is proportional to the distance to the liquid surface. In practice, there are two kinds of radar level gauge means the frequency modulation continuous wave and pulse wave. Liquid level meter adopts frequency modulation wave technology, power consumption is big, the four wire system, should be used in electronic circuit is plicated. And the radar pulse wave technology level gauge, low power consumption, easy to implement essential safety, high precision, wider application scope. Radar level gauge measuring the electromagic waves can pass through a vacuum, don39。t remend using noncontact radar, generally remend a director radar. Finally is the temperature on the accuracy, of course, must be higher than the ultrasonic, radar must use high resolution radar in the tank, without ultrasonic. As for the price, usually ultrasonic, lower than the radar in a wide range of course some ultrasonic price is also high. Such as the range of 670 meters, the preferred ultrasonic liquid level meter. Pay attention to the stirring groove, groove wall adhesion can produce interference of the reflected wave, level measurement, the installation is to choose the appropriate installation position, so as to avoid the interference of these factors. Level two categories, including liquid level and material level. Liquid level and liquid level indicator and two continuous level measurement. Liquid level indicator is the level of several fixed position measuring, used in liquid level of upper and lower limit alarm, etc. Continuous level measurement is to measure liquid level continuously, it is widely used in many fields such as petroleum, chemical industry, food processing, have very important significance. For more than 20 kinds of continuous level measurement method for parative analysis. Glass tube, glass plate, double color water method. Manual gauging glass tube method: this method is using the principle of municating vessels, level scale read directly from the instructions. Glass plate method: glass which can be 4 installed through connectors can also be installed in the container wall openings, and series a few piece of glass to increase the range. Numerical scale read directly from the glass plate level. Double color gauge method: this method using the optical principle, make water shows green, and make the water vapor shows red, which indicate the water level. Artificial gauging method: the method is used for measuring oil tank liquid level. When measuring, the surveyor gauge Surveyor to volume of the oil dipstick into oil, and filed when feet lead contact with the tank bottom oil dipstick. According to the quantity of oil traces on the oil dipstick, read out the oil level height。 H level. So the liquid level is measured by the static pressure P can be H. Strong method suitable for measuring the corrosive gas blowing, have suspended material content in the liquid, and is mainly used in the measurement accuracy is not high. Differential pressure method: the open container or atmospheric vessels, valves and gas phase pressure pipeline saves. Based on the relationship between differential pressure and liquid level Δ P