The turbine flow meter is the most common measuring instrument, and it is the earliest legal flow meter in Europe. Most users also like to use the turbine flow meter. There are the gas turbine flow meter and the liquid turbine flow meter. The common classification methods are as follows.
(1) The inductive type
The sensor impeller of the turbine meter is embedded with permanent magnetic material. When the impeller and the permanent magnetic material rotate, the magnetic field will alternately approach and moves away from the detection coil outside the sensor housing, and the induction electromotive force of the coil will also change. The frequency signal of this periodic change is amplified and output.
(2) The variable reluctance type
The impeller blade or the hub is made of magnetic material, and the detection coil outside the sensor housing of the turbine flow meter is equipped with water magnetic material. When the impeller rotates, the magnetic circuit formed by the permanent magnetic material in the circle will approach or move away alternately due to the magnetic conductive blades. In addition, the magnetic flux will change periodically, and the equivalent impedance of the coil also changes and produces continuous pulse waves in the amplifier circuit.
(3) The flute (dry reed pipe) type
The permanent magnetic material embedded in the impeller (or other rotating elements synchronized with it) can periodically open and close the turbine flow meter sensor. The reed of the flute tube outside the shell is electrocuted to cause the constant current (or constant voltage) source to generate an electric pulse signal.
(4) The photoelectric type
The impeller blade or the impeller-driven component will block the light beam as the impeller rotates. The generated optical pulse signal is converted into an electrical pulse signal. In recent years, optical fiber transmission can effectively improve anti-interference performance.
(1) The one-way type
It only allows fluid to flow into the sensor from one direction, and a check valve should be installed where is a possibility of backflow.
(2) The two-way type
It allows fluid to flow into the sensor from both positive and negative directions. There are two signal detectors, and the flow display instrument can distinguish the phase of the signal. The cumulative amount uses "plus" or "minus" to deal with the total amount of flow in the "positive" or "negative" directions, such as the turbine flow meter for submarines.
(1) The flange connection type
The turbine flow meter sensor is connected to the pipeline in a flanged form. The flange is in accordance with the national standard, and the pressure is limited to 6.3Mpa or less.
(2) The threaded connection type
The turbine flow meter sensor is connected to the pipeline in a threaded manner. There are sealed pipeline threads and unsealed pipeline threads, which can withstand high pressure, but are not suitable for larger diameters.
(3) The clamping type
The turbine flow meter sensor itself has no flange, it relies on the flange on the pipeline to hold the two sealed end faces of the turbine flow meter sensor. It is easy to install, but it is not suitable for higher pressures and larger diameters.