Turbine flow meter correct selection method
2024-10-14
Turbine flow meters are widely used in various industries. The choice of flowmeter needs to be determined by a variety of factors, such as measuring medium, accuracy, temperature and pressure, flow rate range, etc., so how to choose the right flowmeter according to the parameters? Let's learn more about it:
1. Selection of sensor of turbine flowmeter
a. Suitable for measuring fluids: Turbine flow sensors are suitable for measuring clean (or basically clean) low-viscosity single-phase fluids (gases or liquids), such as water, light oil, petroleum solvents, acids, alkalis, liquid oxygen, liquid nitrogen, liquid hydrogen, air, oxygen, etc. If high viscosity liquid is measured, the measurement accuracy will be reduced due to the influence of viscosity on the sensor performance. If the liquid mixed with solid particles is measured, the turbine flowmeter is not suitable for use because of the easy damage to the bearing. When measuring highly corrosive liquids, it will cause difficulties in the selection of major components such as impellers, and its corrosion resistance has certain limitations, which should be carefully selected. Gas measurement is suitable, but because of the low gas density and high flow rate, special consideration must be given to the design of structural parameters. Generally can not be used for the measurement of gas-liquid miscible flow and steam.
b. Selection of caliber: Each caliber sensor has a certain flow measurement range. The selection of the general sensor caliber is determined by the flow range, even if the small flow when used shall not be lower than the small flow allowed to be measured by the caliber, the large flow when used shall not be higher than the large flow allowed to be measured by the caliber. From the perspective of measurement accuracy and service life, it is generally believed that in the case of intermittent use (actual operation of less than 8h per day), 1.3 times of the actual use of the large flow rate is selected. For continuous use (daily actual operation of more than 8h), the sensor caliber is selected according to 1.4 times of the large flow rate in actual use. As for the use under harsh working conditions (such as easily vaporized liquids, liquids containing small particles, etc.), the large flow rate when used should be 40% of the large flow rate allowed by the caliber. If the diameter of the sensor is inconsistent with the diameter of the process pipe, the pipe should be modified with reducing pipe and equal pipe. Under normal circumstances, the error near the lower limit of the sensor flow range is slightly larger, and 0.8 times of the actual small flow rate is usually used as the lower limit of the flow range of the sensor, and there is a certain margin.
c. Bearing selection: In order to improve the measurement accuracy of the transmitter, strive to minimize the friction torque between the shaft and the bearing. Generally, rolling bearings are used for the measurement of fluids with good lubrication (gasoline, kerosene, etc.); Sliding bearings with self-lubrication (such as plastic, graphite and carbon bearings, etc.) are used in the measurement of non-lubricating liquids; Superhard alloy bearings (such as tungsten carbide bearings, etc.) are used for fluids that are easy to vaporize, fluids mixed with small particles, corrosive fluid measurements, and the continuous use of transmitters.
2. Precautions for the use of turbine flowmeter
a. If no bypass pipe is installed, open the upstream valve of the flow sensor at a medium opening and then slowly open the downstream valve. Run at a low flow rate for a period of time (such as lOmin), then fully open the upstream valve, and then open the downstream valve to adjust to the required normal flow rate.
b. For a flow sensor equipped with a bypass pipe, fully open the bypass pipe valve, open the upstream valve of the flow sensor with a medium opening, slowly open the downstream valve, and turn down the bypass valve opening to enable the meter to run at a low flow rate for a period of time. Then fully open the upstream valve, fully close the bypass valve (ensure that the bypass valve does not leak), and adjust the downstream valve opening to the required flow rate.
c. For cold and high temperature fluids, the water in the pipe is drained prior to circulation by running at a very low flow rate of 15 nun before gradually rising to normal flow. When stopping the flow, it should be carried out slowly, so that the pipe temperature and the ambient temperature are gradually close to each other.
d. The opening and closing of the valve should be as gentle as possible, such as the automatic control of the valve opening and closing, the use of "two sections open, two sections close" to prevent fluid sudden impact on the impeller or even water hammer phenomenon damage to the impeller.
e. When the pipeline pressure is not high, the downstream pressure of the flow sensor should be checked. Generally, in the early stage of operation, observe whether the downstream pressure of the sensor is greater than p of equation (1-46) when the large flow rate is put into operation. Otherwise measures should be taken to prevent the formation of air pockets.
f. Correctly handle the meter coefficient of the flow sensor. The meter coefficient K of the turbine flow meter is filled in by the manufacturer on the check list to the user, so as to avoid loss. When used, the internal coefficient switch and multiplier switch used in the display instrument should be carefully checked, and their positions should be consistent with the corresponding sensor coefficient. After the turbine flow sensor is used for a long time, the meter coefficient K will change due to bearing wear and other reasons, and it should be checked on site or offline regularly. If the measurement error exceeds the water cycle, the standby sensor should be replaced in time, and the display meter should be reset in time according to the meter coefficient of the new sensor.
g. The process process requiring regular cleaning of the pipeline (such as when the finished oil pipeline is replaced or stopped), the flow direction, flow rate, pressure and temperature of the fluid used in the cleaning of the pipeline should comply with the provisions of the turbine flow sensor.
h. When using high temperature steam to clean the pipeline, avoid high temperature steam flowing through the sensor to avoid damage.
3. Maintenance of turbine flowmeter
In order to ensure the long-term normal operation of the turbine flow meter, it is necessary to regularly check the operating status of the sensor, display instrument or flow computer, and auxiliary equipment, do a good job in maintenance, and eliminate abnormalities in time.
a. Regularly disassemble, inspect and re-calibrate the turbine flowmeter; The sensor with lubricating oil or cleaning liquid injection should be injected regularly according to the requirements of the manual to maintain the good operation of the impeller. If the impeller has abnormal sound, it should be removed in time to check the internal parts of the sensor. When bearings and shafts are seriously worn, they should be replaced and re-calibrated.
b. Monitor the working condition of the display instrument (dial to "self-calibration"), evaluate the reading of the display instrument, and check it in time if any abnormal phenomenon is suspected.
c. Keep the filter unblocked, the filter is blocked by impurities, which can be judged from the increase of the difference in the reading of the pressure gauge at the entrance and exit, and remove in time, otherwise the blockage will seriously reduce the flow rate. When the gas sensor that escapes from the liquid in the gas eliminator is removed from the pipeline and is temporarily not used, it should be cleaned with light oil and protected at both ends to prevent rust or impurities from entering the instrument.
If you want to know more about the flow meter or flow meter selection, please consult the Aister flow meter manufacturer email: sales@aistermeter.com for help.
1. Selection of sensor of turbine flowmeter
a. Suitable for measuring fluids: Turbine flow sensors are suitable for measuring clean (or basically clean) low-viscosity single-phase fluids (gases or liquids), such as water, light oil, petroleum solvents, acids, alkalis, liquid oxygen, liquid nitrogen, liquid hydrogen, air, oxygen, etc. If high viscosity liquid is measured, the measurement accuracy will be reduced due to the influence of viscosity on the sensor performance. If the liquid mixed with solid particles is measured, the turbine flowmeter is not suitable for use because of the easy damage to the bearing. When measuring highly corrosive liquids, it will cause difficulties in the selection of major components such as impellers, and its corrosion resistance has certain limitations, which should be carefully selected. Gas measurement is suitable, but because of the low gas density and high flow rate, special consideration must be given to the design of structural parameters. Generally can not be used for the measurement of gas-liquid miscible flow and steam.
b. Selection of caliber: Each caliber sensor has a certain flow measurement range. The selection of the general sensor caliber is determined by the flow range, even if the small flow when used shall not be lower than the small flow allowed to be measured by the caliber, the large flow when used shall not be higher than the large flow allowed to be measured by the caliber. From the perspective of measurement accuracy and service life, it is generally believed that in the case of intermittent use (actual operation of less than 8h per day), 1.3 times of the actual use of the large flow rate is selected. For continuous use (daily actual operation of more than 8h), the sensor caliber is selected according to 1.4 times of the large flow rate in actual use. As for the use under harsh working conditions (such as easily vaporized liquids, liquids containing small particles, etc.), the large flow rate when used should be 40% of the large flow rate allowed by the caliber. If the diameter of the sensor is inconsistent with the diameter of the process pipe, the pipe should be modified with reducing pipe and equal pipe. Under normal circumstances, the error near the lower limit of the sensor flow range is slightly larger, and 0.8 times of the actual small flow rate is usually used as the lower limit of the flow range of the sensor, and there is a certain margin.
c. Bearing selection: In order to improve the measurement accuracy of the transmitter, strive to minimize the friction torque between the shaft and the bearing. Generally, rolling bearings are used for the measurement of fluids with good lubrication (gasoline, kerosene, etc.); Sliding bearings with self-lubrication (such as plastic, graphite and carbon bearings, etc.) are used in the measurement of non-lubricating liquids; Superhard alloy bearings (such as tungsten carbide bearings, etc.) are used for fluids that are easy to vaporize, fluids mixed with small particles, corrosive fluid measurements, and the continuous use of transmitters.
2. Precautions for the use of turbine flowmeter
a. If no bypass pipe is installed, open the upstream valve of the flow sensor at a medium opening and then slowly open the downstream valve. Run at a low flow rate for a period of time (such as lOmin), then fully open the upstream valve, and then open the downstream valve to adjust to the required normal flow rate.
b. For a flow sensor equipped with a bypass pipe, fully open the bypass pipe valve, open the upstream valve of the flow sensor with a medium opening, slowly open the downstream valve, and turn down the bypass valve opening to enable the meter to run at a low flow rate for a period of time. Then fully open the upstream valve, fully close the bypass valve (ensure that the bypass valve does not leak), and adjust the downstream valve opening to the required flow rate.
c. For cold and high temperature fluids, the water in the pipe is drained prior to circulation by running at a very low flow rate of 15 nun before gradually rising to normal flow. When stopping the flow, it should be carried out slowly, so that the pipe temperature and the ambient temperature are gradually close to each other.
d. The opening and closing of the valve should be as gentle as possible, such as the automatic control of the valve opening and closing, the use of "two sections open, two sections close" to prevent fluid sudden impact on the impeller or even water hammer phenomenon damage to the impeller.
e. When the pipeline pressure is not high, the downstream pressure of the flow sensor should be checked. Generally, in the early stage of operation, observe whether the downstream pressure of the sensor is greater than p of equation (1-46) when the large flow rate is put into operation. Otherwise measures should be taken to prevent the formation of air pockets.
f. Correctly handle the meter coefficient of the flow sensor. The meter coefficient K of the turbine flow meter is filled in by the manufacturer on the check list to the user, so as to avoid loss. When used, the internal coefficient switch and multiplier switch used in the display instrument should be carefully checked, and their positions should be consistent with the corresponding sensor coefficient. After the turbine flow sensor is used for a long time, the meter coefficient K will change due to bearing wear and other reasons, and it should be checked on site or offline regularly. If the measurement error exceeds the water cycle, the standby sensor should be replaced in time, and the display meter should be reset in time according to the meter coefficient of the new sensor.
g. The process process requiring regular cleaning of the pipeline (such as when the finished oil pipeline is replaced or stopped), the flow direction, flow rate, pressure and temperature of the fluid used in the cleaning of the pipeline should comply with the provisions of the turbine flow sensor.
h. When using high temperature steam to clean the pipeline, avoid high temperature steam flowing through the sensor to avoid damage.
3. Maintenance of turbine flowmeter
In order to ensure the long-term normal operation of the turbine flow meter, it is necessary to regularly check the operating status of the sensor, display instrument or flow computer, and auxiliary equipment, do a good job in maintenance, and eliminate abnormalities in time.
a. Regularly disassemble, inspect and re-calibrate the turbine flowmeter; The sensor with lubricating oil or cleaning liquid injection should be injected regularly according to the requirements of the manual to maintain the good operation of the impeller. If the impeller has abnormal sound, it should be removed in time to check the internal parts of the sensor. When bearings and shafts are seriously worn, they should be replaced and re-calibrated.
b. Monitor the working condition of the display instrument (dial to "self-calibration"), evaluate the reading of the display instrument, and check it in time if any abnormal phenomenon is suspected.
c. Keep the filter unblocked, the filter is blocked by impurities, which can be judged from the increase of the difference in the reading of the pressure gauge at the entrance and exit, and remove in time, otherwise the blockage will seriously reduce the flow rate. When the gas sensor that escapes from the liquid in the gas eliminator is removed from the pipeline and is temporarily not used, it should be cleaned with light oil and protected at both ends to prevent rust or impurities from entering the instrument.
If you want to know more about the flow meter or flow meter selection, please consult the Aister flow meter manufacturer email: sales@aistermeter.com for help.
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