The glass rotor flowmeter has strong corrosion resistance, and can detect the flow of corrosive gases or liquids such as acid (except hydrofluoric acid), alkali and oxidant, and is suitable for industries such as chemical industry, pharmaceutical industry, paper making and sewage treatment. The development of flow measurement can be traced back to ancient water conservancy projects and urban water supply systems. In the era of Caesar in ancient Rome, orifice plates were used to measure the drinking water of residents. Around 1000 BC, ancient Egypt used the weir method to measure the Nile flow. The famous Dujiangyan water conservancy project in China uses the bottle mouth water level to observe the water quantity and so on. /kloc-in the 0/7th century, Torricelli laid the theoretical foundation of differential pressure flowmeter, which is a milestone of flow measurement. Since then, the rudiments of various types of flow measuring instruments in the 18 and 19 centuries have begun to take shape, such as weir type, tracer method, pitot tube, venturi tube, volumetric type, turbine type and target flowmeter. In the 20th century, the rapid growth of demand for flow measurement in process industry, energy metering and urban public utilities promoted the rapid development of instruments. The rapid development of microelectronics and computer technology has greatly promoted the upgrading of instruments, and new flowmeter has sprung up like mushrooms after rain. So far, it is said that hundreds of flowmeters have been put into the market, and many problems in field use are expected to be solved.
The work of modern flow measurement technology in China is relatively late, and all the flowmeters needed in the early stage are imported from abroad.
Flow measurement is a science that studies the quantitative change of substances, and the law of mutual change of mass is the basic law of the development of things, so its measurement object is not limited to pipeline liquid in the traditional sense, and there are problems in flow measurement wherever quantitative change is needed. Flow rate, pressure and temperature are juxtaposed as three major detection parameters. For a certain fluid, as long as these three parameters are known, its energy can be calculated, and these three parameters must be detected in the measurement of energy conversion. Energy conversion is the basis of all production processes and scientific experiments, so flow, pressure and temperature instruments are widely used. In order to make the rotor flowmeter work normally and achieve certain measurement accuracy, the following points should be paid attention to when installing the flowmeter:
1. The rotameter must be installed vertically on the vibration-free pipeline. The fluid flows through the flowmeter from bottom to top, the verticality is better than 2, and the horizontal included angle is better than 2 when it is installed horizontally; (Now there is a rotameter that can be installed horizontally)
2. In order to facilitate the maintenance and replacement of the flowmeter and the cleaning of the measuring pipeline, the metal tube float flowmeter installed on the process pipeline should be equipped with a bypass pipeline and a bypass valve;
3. At the entrance of the rotary flowmeter, there should be a straight pipe section with a length greater than 5 times the pipe diameter, and at the exit, there should be a straight pipe section with a length of 250mm;
4. If the medium contains ferromagnetic substances, a magnetic filter should be installed; If the medium contains solid impurities, consider installing a filter between the valve and the straight pipe section;
5. When used for gas measurement, ensure that the pipeline pressure is not less than 5 times of the pressure loss of the flowmeter, so as to make the float work stably;
6. In order to avoid the deformation of flowmeter caused by pipeline, the flange of process pipeline must be coaxial with the flange of flowmeter and parallel to each other, and support the pipeline to avoid pipeline vibration and reduce the axial load of flowmeter. The control valve in the measuring system should be installed downstream of the flowmeter;
7. When measuring gas, if the gas is directly discharged into the atmosphere at the outlet of the flowmeter, a valve should be installed at the outlet of the instrument, otherwise a pressure drop will be generated at the float, which will distort the data.
8. When installing the instrument with PTFE lining, the hexagon nut with flange should not be tightened asymmetrically at will, so as not to cause the deformation of PTFE lining;
9. For instruments with LCD display, direct sunlight should be avoided as far as possible to avoid reducing the service life of LCD; For instruments powered by lithium batteries, direct sunlight and high temperature environment (≥65℃) should be avoided as far as possible to avoid reducing the capacity and life of lithium batteries. 1. In the selection of the long-distance metal pipe float rotameter, the rotameter suitable for the explosion-proof requirements of the use place should be selected; During installation, attention should also be paid to the fastening of the shell and the sealing of the connecting port after the instrument is electrified, which has reached the requirements of explosion-proof, protection and corrosion protection.
2. In places where the measured medium temperature is too high (> 120℃) or the temperature is low, thermal insulation measures are usually taken for the sensor part of the rotary flowmeter. In order to ensure the normal working environment temperature of the signal conversion indicator, the high temperature indicator should be selected.
3. For some measured media that need heat preservation or cooling, a jacketed rotameter should be selected. The heating or cooling interface of standard metal tube float rotor flowmeter adopts DIN 2501DN15PN1.6 flange connection. If other flanges or threaded connections are needed, please indicate them when ordering.
4. For the pressure instability of the inlet medium of the rotary flowmeter, especially for gas measurement, in order to ensure the accuracy and service life, the damping structure should be selected.
5. If the pressure grade required by the medium is higher than the standard pressure grade, please choose the high-pressure structure when selecting the type, and the high-pressure type adopts HG20595-97 RF neck butt welded steel pipe flange. If other standards are adopted, please indicate them when ordering.
6. When installing the rotor flowmeter, ensure that the verticality of the measuring tube is better than 5%, and a bypass should be installed to facilitate maintenance and cleaning without affecting production.
7. The installation position of the rotor flowmeter shall ensure that the inlet has a straight pipe section of ≥5DN or more and the outlet has a straight pipe section of ≤250mm or less; If the medium contains ferromagnetic substances, a magnetic filter should be installed in front of the rotameter.
8. The control valve in the measurement and control system shall be installed downstream of the rotameter. When used for gas measurement, the working pressure should be guaranteed to be not less than 5 times of the pressure loss of the rotary flowmeter, so as to make the rotary flowmeter work stably.
9. Before installing the metal tube float rotor flowmeter, the welding slag in the pipeline should be purged clean; When installing, take out the stop element in the rotameter; When used after installation, the control valve should be opened slowly to avoid impact damage to the rotor flowmeter. Rotor flowmeter has the characteristics of simple structure, reliable operation, wide application range, accurate measurement, convenient installation and so on, and is resistant to high temperature and high pressure. How to eliminate common faults in flowmeter operation?
First, there is no current output.
1. First, check whether the wiring is correct.
2. Is the LCD screen displayed? If there is, there is no output, mostly the output tube is broken, and the circuit board needs to be replaced.
3. The calibration value is lost. Due to the failure of E2PROM, the calibration data of the instrument will be lost, there will be no output current, and the current will remain unchanged. Solution: You can use the data recovery operation. If not, you can set the data in password 2000 first, and then set the data in password 40 1 1. The method is to calibrate the data from RP to 100% by pushing the pointer.
Second, there is no live display.
1. Check whether the wiring is correct.
2. Check whether the power supply is correct.
3. Reinstall the LCD module and check the contact.
4. For the multi-line power supply mode, check whether the terminals 12 and 13 are connected to the ammeter or short-circuited.
Third, the alarm is incorrect.
1. Check that the deviation setting d value cannot be too large.
Whether the logical function in 2.2 is correct. Interesting function. HA-A stands for upper bound positive logic. LA-A stands for lower bound positive logic.
3. Check the alarm value setting size in SU.
4. If the LCD bar code indicates correctly and the output is invalid, check whether the external power supply and the negative pole of the external power supply are connected with the negative pole of the instrument power supply.
Four, the rotor flowmeter pointer jitter:
1. Slight jitter of pointer: generally caused by medium fluctuation. It can be overcome by increasing damping.
2. Moderate pointer jitter: generally caused by the flowing state of the medium. For gas, it is generally caused by the unstable working pressure of the medium. Pressure stabilizing or flow stabilizing devices can be used to overcome or increase the air damping of the float flowmeter.
3. The pointer jitter is serious: the overrange of the float flowmeter is mainly due to medium pulsation, unstable air pressure or the pressure, temperature and flow rate of the gas operation state given by the user are different from the actual state of the float flowmeter.
Five, float flowmeter pointer stopped at a certain position.
The main reason is that the float of the float flowmeter is stuck.
Generally, when the float flowmeter is used, the valve is opened too fast, which causes the float to hit the plug quickly, causing the plug to deform and jam the float. However, it does not rule out that the float is stuck because the float guide rod is not concentric with the stop ring. When handling, you can take out the instrument, take out the deformed stopper for shaping, and check whether it is concentric with the guide rod. If you don't agree, you can correct it. Then, install the float, push it by hand, and feel the float go up and down smoothly. In addition, when installing the float flowmeter, it must be installed vertically or horizontally, and it must not be tilted, otherwise it will easily cause meter jamming and bring errors to measurement.
Six, the float flowmeter measurement error is large.
1. The installation does not meet the requirements.
For the vertically installed float flowmeter, it should be vertical and the inclination angle should not be greater than 20 degrees.
For the float flowmeter installed horizontally, keep it horizontal and the inclination shall not exceed 20 degrees.
There should be no ferromagnetic objects in the space around the float flowmeter 100 mm.
The installation position should be far away from the valve reducer, pump outlet, process pipeline corner, etc. After the first 5 days, keep the requirement of 250 mm straight pipe section.
2. The large change of liquid medium density is also a reason for the large error. Before the instrument is calibrated, the medium is converted according to the density given by the user and converted into the flow rate of water in the calibration state, so if the density of the medium changes greatly, the measurement error will be large. This scheme can bring the changed medium density into the formula and convert it into an error correction coefficient, and then multiply the flow measured by the flowmeter by this coefficient to convert it into a real flow.
3. Because the gas medium is greatly influenced by temperature and pressure, it is suggested to use temperature and pressure compensation to obtain the real flow.
4. Due to factors such as long-term use and pipeline vibration, the moving parts of the float flowmeter, such as sensing magnet, pointer, counterweight and rotating magnet, are loose, resulting in large errors. Solution: You can verify it by pushing the pointer first. First, press the pointer at the RP position to see whether the output is 4mA and the flow display is 0%, and then press the scale in turn to verify. If any discrepancy is found, the position of the part can be adjusted. Generally, professional adjustment is needed, otherwise the position will be lost and it needs to be returned to the manufacturer for correction.
Seven, the cumulative pulse output is incorrect.
1. Check whether the alarm value of the selected cumulative pulse output is set to zero.
2. Circuit board failure, replace the circuit board.
Eight, metal rotor flowmeter liquid crystal total display 0 or full scale.
1. Check the range and zero parameters set in the 2000 password. A value of zero less than SPAN is required, and the two values cannot be equal.
2. Check whether the sampled data has come up, and press the pointer to see the change of the sampled value. If there is no change, it is generally that the sampling circuit of the circuit board is faulty and the circuit board needs to be replaced.
5. Circuit board failure, replace the circuit board.