200 Level

202 - Chapter 2

Magnetic Drives

If you don’t need high head capacity, you can save operating costs by lightening the impeller and eliminating the seals, and that’s exactly what Magnetic Drive pumps do. Imagine taking a ‘doughnut’ of copper wire and ‘frosting’ it with a waterproof icing. If you suspend a magnet inside that doughnut and connect the coil to power, the magnet will spin, by magnetic induction. Attach an impeller to the magnet and presto! You have a Mag Drive. The pros are: there are no seals to deal with; energy consumption can be very modest and the simple impeller is easy to replace. On the other hand, Mag Drives don’t have the power to produce a lot of flow or head pressure, so they’re mainly useful in smaller ponds, under 2000 gallons. One other quirk -- that magnet that spins when the coil is energized? Well, you never know which direction it’s going to turn on startup, so the impeller has to be able to work in either direction. If you can get the magnet to spin in only one direction, you can make a more efficient impeller and Presto!...