Precautions for installing turbine flowmeters and wiring requirements

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　　A turbine flowmeter consists of a turbine, bearings, a pre-amplifier, and a display instrument. The internal structure of such flowmeters varies depending on whether they are used for measuring liquids or gases. Since gases are greatly affected by temperature and pressure, temperature and pressure compensation devices are generally required when measuring gases at high temperatures, in order to improve the accuracy of the measurement results. When the fluid under test impacts the turbine blades, causing the turbine to rotate, its speed changes depending on the flow rate – higher flow rates result in a higher turbine speed. The turbine’s speed is then converted into electrical pulses of corresponding frequency by a magnetoelectric conversion device; after being amplified by a preamplifier, these pulses are sent to a display instrument for counting and showing. The instantaneous flow rate and cumulative flow rate can be determined based on the number of pulses per unit time and the total number of pulses accumulated. Most customers choose the flange-mounted type, as it can be directly connected to the flanges on the pipes upon installation. However, there are still a few minor requirements regarding wiring and installation that need to be taken into account. 　　I. Wiring requirements for turbine flowmeters 1. Use a single, complete cable whenever possible. 　　2. The wiring location of the turbine flowmeter should be as far away as possible from sources of electrical noise (such as high-power transformers, motors, and strong power cables), and it should be avoided to be wired in parallel with the power supply cables. 　　3. It is recommended to use non-soldered clamping terminals at the ends of thick wires. 　　4. In areas with a strong external magnetic field, the axis of the detection device should be perpendicular to the direction of the magnetic flux of the external field, or the flow sensor or the external magnetic source should be shielded using highly magnetic conductive materials. 　　5. To prevent water ingress and mechanical damage, it is advisable to place the cables inside metal conduits; however, high-power transmission cables should not be placed in the same conduit. (If the maximum power transmitted by one cable is 10 times greater than the minimum power transmitted by the flow meter signal cable, the two cannot be installed in the same conduit.) 　　6. The connection of the cable for the sensor of the explosion-proof turbine flowmeter must strictly comply with the relevant standards for explosion-proof amplifiers. 　　II. Precautions for the installation of turbine flowmeters: 1. The power cable of the transmitter should be a metal-shielded cable, with reliable grounding. The power supply is 24V DC with an impedance of 650Ω. 　　2. The transmitter should be installed horizontally, avoiding vertical installation, and appropriate straight pipe sections should be ensured in front of and behind it, generally 10D in front and 5D behind. 　　3. Ensure that the flow direction of the fluid is consistent with the arrow on the instrument housing; it must not be installed in the reverse direction. 　　4. The medium under test must not be corrosive to the turbine, especially at the bearings; otherwise, measures should be taken. 　　5. Be careful not to collide with the magnetic induction section. Flow metering is one of the components of measurement science and technology, and it is closely related to the national economy, national defense construction, and scientific research. Flow metering is widely used in various fields such as industrial and agricultural production, national defense construction, scientific research, foreign trade, and people’s daily lives.