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Liquid turbine flowmeter (threaded)
Turbine flowmeter is a velocity type instrument that has the advantages of high accuracy, good repeatability, simple structure, low pressure loss, and
Product details
Turbine flowmeter is a speed type instrument that has the advantages of high accuracy, good repeatability, simple structure, high pressure resistance, wide measurement range, small volume, light weight, low pressure loss, long service life, simple operation, and easy maintenance. It is used to measure the volume flow rate and cumulative flow rate of low viscosity, non corrosive, and clean liquids in closed pipelines. It can be widely used in industries such as petroleum, chemical, metallurgy, organic liquids, inorganic liquids, food, and pharmaceuticals.
The fluid flows through the sensor housing. Due to the angle between the blades of the impeller and the flow direction, the impulse of the fluid causes the blades to have a rotational torque. After overcoming the friction torque and fluid resistance, the blades rotate. After the torque is balanced, the speed is stable. Under certain conditions, the speed is proportional to the flow rate. Due to the magnetic conductivity of the blades, they are in the magnetic field of the signal detector (composed of * * magnetic steel and coils). The rotating blades cut the magnetic field lines and periodically change the magnetic flux of the coil, causing electrical pulse signals to be induced at both ends of the coil. This signal is amplified and shaped by an amplifier to form a continuous rectangular pulse wave with a certain amplitude, which can be transmitted to a display instrument remotely to display the instantaneous flow rate or total amount of the fluid. Within a certain flow range, the pulse frequency f is proportional to the instantaneous flow rate Q of the fluid flowing through the sensor, and the flow equation is:
In the formula:f---------Pulse frequency [Hz]K-----------The instrument coefficient of the sensor [1/m3] is given by the calibration sheet. If [1/L] is used as the unit
In the formula:Q---------Instantaneous flow rate of fluid (working state) [m3/h] 3600---------------Conversion factor;
The instrument coefficient of each sensor is filled in the calibration certificate by the manufacturer, and the k value is set in the matching display instrument to display the instantaneous flow rate and cumulative total amount.
The relationship curve between flowmeter coefficient and flow rate (or Reynolds number) is shown in the figure on the right. The instrument coefficient is divided into two segments, namely the linear segment and the nonlinear segment. The linear segment is about two-thirds of its working segment, and its characteristics are related to the sensor structure size and fluid viscosity. The nonlinear segment characteristics are greatly affected by bearing friction and fluid viscous resistance. When the flow rate is below the lower limit of the sensor flow rate, the instrument coefficient changes rapidly with the flow rate. When the flow rate exceeds the upper limit, attention should be paid to preventing cavitation.
High precision, generally achievable± 1% R, ± 0.5% R (R refers to reading error);
Good repeatability, short-term repeatability can be achieved0.05% to 0.2%.
On site display, instantaneous flow and cumulative flow;
Can obtain high frequency signals with strong signal resolution;
Range width ratioThe medium to large caliber can reach 1:20, while the small caliber is 1:10;
Compact and lightweight structure, easy installation and maintenance, and high circulation capacity;
Support flow rate conversion display function, convenient for on-site viewing of current flow rate;
support4-20mA output, pulse (equivalent) output, alarm output, RS485 communication output.
1. Main technical parameters
| Measurement medium | No impurities, no strong corrosiveness, low viscosity liquid | |||
| Execution standards | Turbine flow sensor (JB/T9246-1999) | |||
| Verification regulations | Turbine flowmeter (JJG1037-2008) | |||
| Instrument caliber connection method | flange type | DN15-DN200 | ||
| Threaded connection type | DN4-DN50 | |||
| Clamp connection type | DN25-DN50 | |||
| Flange standard | Conventional standards | GB/T9113-2000 | ||
| Other standards | International pipe flange standard | Such as German standard DIN, American standard ANSI, Japanese standard JIS | ||
| Domestic pipe flange standards | Such as the standards of the Ministry of Chemical Industry and the Ministry of Machinery | |||
| thread specification | regular size | British pipe thread (external thread) | ||
| Other specifications | Internal thread, NPT thread, etc | |||
| Accuracy level and corresponding repeatability | accuracy class | ±1%R | ±0.5%R | ± 0.2% R (customization required) |
| Linearity | ≤0.15% | ≤0.1% | ≤0.03% | |
| Range ratio | 1：10； 1：15； 1:20 | |||
| Instrument material | 304 stainless steel; 316 stainless steel | |||
| Temperature of the tested medium (℃) | -20℃～+110℃ | |||
| Verification conditions | environmental condition | ambient temperature | 20℃ | |
| relative humidity | 65% | |||
| verification device | Standard table method liquid flow verification device | |||
| Static mass method liquid flow verification device | ||||
| Conditions of Use | ambient temperature | -20℃～+60℃ | relative humidity | 5%～90% |
| atmospheric pressure | 86Kpa～106Kpa | |||
| output signal | pulse frequency signal | |||
| Two wire 4-20mA DC current signal | ||||
| 485 communication | ||||
| power supply | 24V DC | |||
| Distance | ≤1000m | |||
| Signal line interface | Basic type: Hirschman connector, explosion-proof type: internal thread M20 * 1.5 | |||
| Explosion proof grade | Basic Type: Non Explosion proof Product, Explosion proof Type: Exd II CT6 Gb | |||
| protection grade | IP65 | |||
2. Caliber Flow Comparison Table
Instrument diameter (mm) |
Normal flow range (m3/h) | Lower limit expansion range (m3/h) | Instrument diameter (mm) | Normal flow range (m3/h) | Lower limit expansion range（m3/h） |
| DN4 | 0.04～0.25 | DN50 | 5~40 | 4~40 | |
| DN6 | 0.1～0.6 | DN65 | 7~70 | 4~70 | |
| DN10 | 0.2～1.2 | DN80 | 12~100 | 10~100 | |
| DN15 | 0.7～6 | 0.6-6 | DN100 | 25~200 | 20~200 |
| DN20 | 0.8～8 | 0.45～8 | DN125 | 25~250 | 13~250 |
| DN25 | 1.2～10 | 1-10 | DN150 | 50~400 | 40~400 |
| DN32 | 1.5～15 | 0.8～15 | DN200 | 100~800 | 80~800 |
| DN40 | 2.5～20 | 2-20 | DN300 | 300-2500 | 250-2500 |
1. Installation conditions and location
The pipeline must be completely filled with liquid. It is important to keep the pipeline completely filled with liquid at all times, otherwise the flow display may be affected and measurement errors may occur. |
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Avoid bubbles. If bubbles enter the measuring tube, the flow display may be affected, which may lead to measurement errors. |
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2Typical installation pipeline system diagram of turbine flowmeter
3. Requirements for installing straight pipe sections
The length of the straight pipe section of the turbine flowmeter is sensitive to the distortion of flow velocity distribution and rotational flow inside the pipeline. When entering the sensor, turbulence should be fully developed. Therefore, necessary straight pipe sections or rectifiers should be equipped according to the type of upstream flow resistance components of the sensor, and the length of the straight pipe sections at the inlet and outlet should be required. | ||||||||||||||||||||||||
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4. Common faults and solutions
| Fault phenomenon | Possible reasons | Elimination methods |
| When the fluid flows normally, there is no display, and the total count counter does not increase in words | 1. Check for open circuits or poor connections in the power and signal wires. | 1. Use an ohmmeter to troubleshoot the fault point. |
| 2. Check the internal fault of the sensor. If the above confirmation is normal or the fault is eliminated, but there is still a fault phenomenon, it indicates that the fault is inside the sensor flow channel. Check whether the impeller touches the inside of the sensor, whether it is stuck or not, and whether there are impurities or fractures in the shaft and bearings. | 2. After removing foreign objects and cleaning or replacing bearings and other parts, re inspection should be carried out to obtain new instrument coefficients. | |
| No flow reduction operation was performed, but the flow display gradually decreased | 1. Is the filter clogged? If the differential pressure of the filter increases, it indicates that debris has clogged. | 1. Clean the filter |
| 2. The valve core on the flow sensor is loose, and the valve opening automatically decreases. | 2. Judging from whether the valve handwheel is effectively adjusted, repair or replace it after confirmation. | |
| 3. The sensor impeller is obstructed by debris or foreign objects enter the bearing clearance, increasing resistance and slowing down speed. | 3. Remove the sensor and clear it, and recheck if necessary. | |
| The fluid does not flow, the flow rate display is not zero, or the indication is unstable | 1. Poor grounding of the transmission line, external interference signals mixed into the input terminal of the display instrument. | 1. Check if the shielding layer and terminals are well grounded. |
| 2. Pipeline vibration causes the impeller to shake, resulting in false signals. | 2. Reinforce the pipeline or clamp brackets before and after the sensor to prevent vibration. | |
| 3. The failure to close the shut-off valve resulted in leakage on the instrument display. | 3. Check or replace the valve. | |
| The difference between the displayed value and the empirical evaluation value is significant | 1. Internal faults in the sensor flow channel, such as fluid corrosion, wear, and obstruction by debris causing abnormal rotation of the impeller, changes in instrument coefficient, blade corrosion or impact, top deformation, affecting normal cutting of magnetic field lines, abnormal output of detection coil signals, and changes in instrument coefficient; The fluid temperature is too high or too low, the shaft and bearings expand or contract, and the clearance changes too much, causing the impeller to rotate abnormally and the instrument coefficient to change. |
1. (1-4) Identify the cause of the malfunction and find solutions based on the specific reasons. 2. Replace the components. 3. Replace the appropriate sensor. |
| 2. Insufficient back pressure of the sensor leads to cavitation, which affects the rotation of the impeller. | ||
| 3. Due to reasons related to pipeline flow, such as the absence of a check valve causing reverse flow, the bypass valve not being tightly closed, and leakage. There is a significant distortion in the flow velocity distribution upstream of the sensor (such as caused by the upstream valve not being fully opened), or there is a significant change in viscosity of pulsating liquid due to temperature. | ||
| 4. Internal malfunction of the display device. | ||
| 5. The failure and demagnetization of the permanent magnet material components in the detector can also affect the measured values when the magnetism weakens to a certain extent. | ||
| The actual flow rate flowing through the sensor has exceeded the flow range specified by the sensor. |
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