The turbine flowmeter is a typical velocity flowmeter. It has the characteristics of high measurement accuracy, fast response and high pressure resistance, so it is increasingly used in industrial production.
The turbine flowmeter works based on the principle of conservation of fluid momentum. The measured fluid pushes the turbine blades to rotate the turbine. Within a certain range, the turbine speed is proportional to the average flow rate of the fluid.
The turbine speed is converted into an electrical pulse signal through a magnetoelectric conversion device, which is amplified and sent to the display and recording instrument, so that the instantaneous flow rate and cumulative flow rate of the measured fluid can be derived.
The following points should be noted during routine maintenance of turbine flowmeters:
(1) The flowmeter sensor should be used within the flow range, nominal pressure and flow direction specified on the certificate.
(2) The temperature and environmental conditions of the measured liquid should comply with the provisions of this instruction manual.
(3) Power the flow meter. When the downstream valve is closed, the flow meter should display zero flow.
(4) When the flowmeter sensor is put into use, all bypass valves should be opened first, then the downstream valve of the flowmeter sensor should be slowly opened, and then the upstream valve should be slowly opened until it is fully open, and then the bypass valve should be slowly closed.
If there is no bypass valve, the upstream valve can be slowly opened, and then the downstream valve can be slowly opened. Be careful not to let the impeller suddenly reach a very high speed.
(5) Under normal use, the flowmeter sensor should be inspected and calibrated once every six months to one year. The period depends on the severity of the working conditions. If the shaft and bearing are found to be severely worn, they should be replaced in time and recalibrated.
(6) During maintenance, unscrew the clamping rings at both ends of the flow sensor and remove the guide seat and impeller from the main body in turn.
Common faults and solutions of turbine flowmeter:
1. Large flow fluctuation
The reasons for large flow fluctuation can be considered from the following aspects:
1. Is the water source pulsating?
(1) Generally speaking, if the flow meter is installed close to the pump, it is easy to generate pulsating flow, which will cause large flow fluctuation. The solution is to increase the straight pipe distance between the pump and the flowmeter to stabilize the flow.
(2) The turbine flowmeter is installed too close to the valve or elbow. When the raw material passes through the valve or elbow, the flow fluctuates.
At this time, it should be kept away from the valve and elbow. Ensuring a certain amount of straight pipe section before and after is a good way to solve the problem.
2. Is there interference?
There are interference sources such as motors, inverters, and strong currents near the turbine flowmeter. Solution: Ground the flowmeter or add a filter capacitor. If the problem still cannot be solved, the best way is to stay away from the interference source.
2. Turbine flowmeter has no flow display
1. First check whether there is a problem with the line, such as signal line falling off, broken line, etc.
2. Separate the sensor and the signal amplifier, connect the signal amplifier to the instrument, and use iron metal to scratch the bottom of the amplifier 2~3mm away. If the instrument displays, it means that there is no problem with the display part.
Please remove the flow sensor from the pipeline and check whether the flow meter impeller is entangled or the impeller is damaged.
3. The flow meter shows that the flow is smaller than the actual flow
The general cause of this problem is that the impeller rotates slowly or the blades are broken. Remove the flow meter from the pipeline and check whether the flow meter is entangled or damaged.