Fault description
Nitrogen flow meter FT-1204A flow meter, open this flowmeter display 400nm3 / h, the total table shows the flow rate, the total number of public works is displayed as 0, the opening, the total table and the public works Table are normal (500nm3 / h) .
Fault analysis processing method:
1. Remove the FT-1204A and find some of the floats and other particles. After cleaning, the float is moved smoothly, no casual phenomenon, reverse venting test, and open this table.
2, with the same specifications of the flow meter as other locations, the problem is still.
3, check the valve before and after this table, found that the flow rate is small, the process is used to adjust the flow, and the process is communicated, the valve adjustment flow after using the table, the valve is fully opened, the problem is solved.
Troubleshooting results:
Can be used normally
Experience and rectification preventive measures:
Treatment issues should be clearly clearing is a meter problem or process problems. After checking the instrument, check from the process perspective, look at the process, the instrument installation (front and rear line up line, mounting position) includes valve opening degree, fluid condition, medium The relationship between density, pressure, temperature, etc.
Knowledge expansion
1. Rotor flow meter principle: Also known as the float flowmeter is one of the constant voltage degradation flow cross-sectional flow meter, from a tapered tube and a rotor (also known as float) in a cone tube constitute.
2, when the fluid is from underwent into the cone, the rotor is intercepted, so that the pressure difference is generated between the rotor, and the rotor rises under the action of the pressure difference. At this time, three: fluid The motion pressure (W) of the rotor, the float (a) of the rotor in the fluid (a) and the gravity of the rotor itself (g). The center of gravity of the rotor is combined with the tapered pipe shaft, and the three powers acting on the rotor are parallel to the tube axis. When the three force reaches a balance (g = a + w), the rotor floats smoothly in a certain position in the tube. For a given rotor flow meter, the rotor size and shape have been determined, so it is known in the fluid, which is known to be a constant, and only the fluid changes to the float of the float varies with the size of the fluid flow rate. Therefore, when the flow rate becomes large or changed, the rotor will move up or down, and the flow cross-sectional area of the respective position changes, until the flow rate changes the corresponding speed when the flow rate becomes a balance, and the rotor is stabilized in the new position. For a given rotor flow meter, the position of the rotor in the taper is a one-or-one correspondence between the flow rate of the fluid flow through the flow of the tape.
3. The rotor flow meter is used more extensive, generally used in measurement, small flow, and flow, measuring medium generally decoction, liquid and gas, vapor that is not easy to crystallize and solidify, no viscosity, and the medium flow rate is slow.
4. Metal tube rotor flow score is in place type and remote transmission, and the range ratio is generally 10: 1, and the accuracy is generally 1.6%.
5. Installation requirements of the entire tube rotor flow meter: the tapered tube of the metal tube rotor flowmeter must be installed vertically, can not be illegible, the application level is strictly calibrated, and the assembly should not be stressed, vertical mounting rotor flow meter As soon as it is down, the horizontal mounting rotor flow meter intermediate is consistent with its marking direction. To facilitate usage and demultiplexing, the bypass valve group is generally required. The remote type metal tube rotor flowmeter is a remote portion of the magnetically coupled to the rotor. If the medium contains small particles adsorbed by the magnetic substance, the rotor is easily worn and the plug, resulting in nothing to measure, The solution is to add a magnetic filter in front. The straight pipe section is usually required to be the top 5 after 3.
6. Bringing and deactive method of metal tube rotor flow meter:
1) Before the flow meter is used, it should be checked whether the installation meets the requirements, whether the pipe is purged clean, whether the pressure test has been completed.
2) After the use of ensures that the flow meter is smoothly operated in its effective measurement range, the large-flow impact rotor is prevented from being damaged during the schedule.
3) After the flow meter stops, it should be checked whether the measuring element is contaminated, and the rotor is adsorbed with iron filings, and the flow element and the rotor are cleaned in time.
Same species or similar problems
1. The flow changes and the float or pointer moves sluggish.
It may be due to the originance of the tricks (the float and the guide shaft, the partial link or pointer card, magnetic coupling magnet is magnetically decreased).
2, the actual flow is different from the indication value. It may be due to float or cylinder corrosion, resulting in an area change. Swifts, fluid properties (density, temperature, pressure) variations in the float or cone pipe, and the like.
Editor in charge: WV
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