Turbine flow meteris a widely used flow measuring device, used in a wide range of industries for both liquids and gases.
涡轮流量计have the ability to measure wide range of flows.Turndown ratiofor turbine flow meters (i.e. the ratio maximum flow / minimum flow that can be measured) can reach values up to 30:1 or even bigger, with good accuracy. Typical error levels can be as low as +- 0.5% of measured flow rate. Accuracy flow measurement is maximized when operating under a turbulent flow profile (highReynolds number, typically bigger than 10,000).
One of the limitations of turbine flow meters is the fact that they have to be used only with clean, low-viscosity, non-corrosive fluids. Generally, it is common practice to install a strainer upstream to a turbine flow meter for protection against particulates.
Structure of turbine flow meters
The basic structure of turbine flow meters includes a bladed rotor axially suspended in the pipe. As the fluid flows through the pipe, the rotor spins at a speed which is proportional to the fluid's velocity. The rotating blades generate a frequency signal proportional to the liquid flow rate, which is sensed by the magnetic pick-up installed outside of the pipe and transferred to the applicable transducer. Electrical pulses can also be added and totalized so that we get the aggregate flow rate over a specific time period.
Figure 1 - Basic structure of turbine flow meters
Advantages of turbine flow meter
- Simple, durable structure
- Easy to install and maintain
- Turbine meters are able to operate under a wide range of temperatures and pressures
- Low pressure drop across the flow meter
- Most effective in applications with steady, high-speed flows
Disadvantages of turbine flow meters
- Require constant backpressure in order to avoid cavitation
- Accuracy adversely affected by bubbles in liquids
- Sensitive to changes in fluid viscosity
- A straight run of pipe upstream and downstream the turbine meter needs to be installed to allow homogenisation of the flow pattern
- Significant bearing wear is another drawback of turbine flow meters. Some manufacturers have developed a ''bearingless design'' in order to resolve this problem.
