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(强烈推荐)基于单片机的液体点滴速度监控装置设计_大学毕业论文设计 - 百度文库

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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 complicated. And the radar pulse wave technology level gauge, low power consumption, easy to implement essential safety, , wider application scope.

Radar level gauge measuring the electromagnetic waves can pass through a vacuum, don't need a transmission medium, is not affected by air, steam, groove volatile fog effect, can be used for such as coarse benzene volatile medium level measurement.

Radar level meter can be used for almost all of the liquid level measurement. Electromagnetic wave on the surface level when firing, signal attenuation, when the signal attenuation through the lead to radar level meter cannot detect enough electromagnetic wave signal, the conductive medium can be a very good reflection of electromagnetic wave, the dielectric constant is greater than 1.5 non conductive medium dielectric constant was 1.0 (air) will also be able to guarantee sufficient reflection wave, dielectric constant, the greater the reflection signal. In practice, almost all medium can reflect enough of reflection wave.

(3) radar level gauge, ultrasonic liquid level meter

Ultrasound and radar is the main measuring principle is different, lead to their different application occasions, radar is given that the dielectric constant of the measured substance, which is given that the density of the material being measured, so the low dielectric constant

material radar measurements will be effect to sell at a discount greatly, the solid matter in general, push components, such as ultrasonic wave was launched by the vibration of the piezoelectric material, so it is can be used in , usually only in the atmospheric pressure containers. The radar can be used in the process of Angle is bigger than ultrasound, small containers or elongated don't recommend using non-contact radar, generally recommend a director radar. Finally is the temperature on the accuracy, of course, must be the ultrasonic, radar must use 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 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, 20 kinds of continuous level measurement method for comparative analysis. Glass tube, glass plate, double color water method.

Manual gauging glass tube method: this method is using the principle of communicating vessels, level scale read directly from the

instructions. Glass plate method: glass which can be 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 layer, to determine is equal to the fluid column pressure in the static pressure, thus P = rho gH type of rho - liquid density; 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, the liquid, and is mainly used in the measurement accuracy is not container or atmospheric vessels, valves and gas phase pressure pipeline saves. Based on the relationship between differential pressure and liquid level P = P2 - P1 = rho gH type: P - positive and negative pressure chamber pressure transmitter; P2 and P1 - led tube pressure; H - level. Differential pressure transmitter will pressure difference transformation for 4 ~ 20 mA dc signal. If the pressure in the measuring range lower limit of the corresponding output signal is greater than or less than 4 mA, are all need to adjust the migration zero migration technology such as spring,

is equal to 4 mA. HTG method: this method is applied to differential pressure oil tank liquid level measurement.

Buoy method: this method USES the middle maglev barrel with fixed to the roof and bottom. Liquid level change driven maglev move up and down the casing, and attract the casing of magnet can move up and down the casing wall, secondary instrument | instrument according to the moving magnet volume to calculate the liquid level.

Floating ball method: this method is using the lever principle of work. Floating ball with liquid level change and around the axis of rotation, the pointer on the drive shaft rotation, and at the other end of the lever balance weight balance, at the same time indicates the level value on the dial. Floating ball method and outside the floating ball type two kinds. Floating ball method is mainly used for of level measurement. The modern servo liquid meter measuring accuracy is the accuracy of 1 mm, and generally of measuring density distribution and average density.

Sinking method: the location of the sinking as the change of liquid level change, but the variation is not equal and level variation. Torque tube sinking method: the torque tube core shaft torsional Angle changes, secondary instrument according to the torsional Angle variation to calculate the liquid level above five kinds of methods are using the buoyancy principle to work.

Such as R, R, l, is a fixed value, as long as the use of epsilon 1, epsilon 2, CH can calculate the liquid level H. Measurement of conductive liquid capacitance method principle, the formula is slightly.

(强烈推荐)基于单片机的液体点滴速度监控装置设计_大学毕业论文设计 - 百度文库.doc ĵWordĵصԣ㸴ơ༭ղغʹӡ
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