Why NdFeB Magnet Used in Dry Type Water Meter

Dry type water meter refers to a rotor type water meter whose measuring mechanism is driven by magnetic elements and whose counter is not in contact with the measured water. The reading is clear, the meter reading is convenient and the measurement is accurate and durable.

NdFeB Magnet Used in Magnetically Drive Dry Type Water Meter

Because the counting mechanism of the dry water meter is separated from the measured water by the gear box or isolation plate, it is not affected by the suspended impurities in the water, so as to ensure the normal operation of the counting mechanism and the clarity of the reading. At the same time, it will not affect the reading of the water meter due to the fog or condensed water drop under the glass caused by the temperature difference between the inside and outside the meter, as in the wet water meter.

Exploded view of dry type water meter

The biggest difference between dry water meter and wet water meter is the metering mechanism. The vane wheel is separated from the sun gear, and the upper end of the vane wheel is coupled with the permanent magnets at the lower end of the sun gear. When the water flow pushes the vane wheel to rotate, the magnets at the upper end of the impeller and at the lower end of the sun gear attract or repel each other to drive the sun gear to rotate synchronously, and the water flow through the water meter is recorded by the central transmission counter.

Core parts for magnet drive water meter

As an instrument for measuring the total volume of water flowing through the tap water pipeline, the dry-type water meter can be used in the fields of industry, commercial buildings and residential buildings. The existing dry-type water meter mainly relies on the magnetic coupling structure to transmit motion. As the key component of the dry-type water meter, it directly affects the performance and function of the dry-type water meter, that is, it determines the range ratio of the dry-type water meter and the metering characteristics, accuracy and stability of the dry-type water meter.

The different magnetic transmission modes of the vane wheel and the sun gear will affect the transmission resistance, thus affecting the sensitivity of the indicator mechanism of the water meter. There are mainly the following magnetic transmission modes: the magnetically coupled transmission mode of axial mutual attraction and the magnetic transmission mode of radial repulsion. The permanent magnet used in the dry-type water meter includes Ferrite, Neodymium Iron Boron, and occasionally Samarium Cobalt magnet. The shape of the water meter magnet used generally includes a ring magnet, a cylinder magnet and a block magnet.

Magnetic Transmission Modes

Compared with the wet water meter, the special magnetically coupled structure of the dry water meter not only guarantees the advantages, but also causes potential problems. Attention should be paid to the use!

1. Because the connection between the impeller shaft of the water meter and the counter center gear is driven by magnetic coupling, the requirements for water pressure and water quality are high. When the water pressure fluctuates greatly, the reverse phenomenon of the water meter often occurs. If the water quality is too poor, the Neodymium magnets on the impeller shaft may be full of impurities, resulting in poor transmission.

2. After long use, the demagnetization of the coupling magnet causes small coupling torque and large starting flow.

3. Although an anti magnetic ring is added at the coupling of the transmission magnet, strong magnetic interference may still affect the metering characteristics of the water meter body.

Post time: Aug-17-2022