Permanent magnet pumps

Permanent-magnet drives for pumps and stirrers are increasingly being used in high-pressure technology [22,23]. The containment shell of the magnet drive, in contrast to canned motors, must take up the full pressure-difference and must have appropriately thick walls. 

Continuous product flows under high-pressure conditions (p > 30 MPa) can only be achieved with hermetic centrifugal pumps. Although the two drive systems that can be used - the permanent magnet coupling and the asynchronous canned motor - have the same mode of operation, they differ in their applications and their safety ranges. 

Magnetic Pumps, Fig. 3 Test and measurement setup for two micropumps of different driving mechanisms (a) permanent magnet with a small DC motor (b) integrated coil (Reprinted from [5] with permission from Dr. Ziaie)... 

One useful experimental setup is shown in Fig. 4(a), the lens-parabola configuration. All the components shown can be immersed in superfluid helium. The focal spot from the pumping laser is produced by a small lens of several mm focal length placed directly in the liquid helium. Generally, some provision must be made for adjusting the focus at low temperatures. In one solution to this [58], the lens is mounted on a thin stainless steel plate, which can be flexed by a permanent magnet... 

For experiments in which microwave and magnetic fields are required to pump transitions between spin sublevels, a sophisticated enhancement of the lens-parabola design has been described [66] which allows low temperature positioning of the sample along two axes without use of electro- or permanent magnets. 

Fig. 2 Schematic diagram of the setup used a) rf-Coil, b) gradient coil, c) inner capillary, d) outer tube, e) temperature and pressure sensors, f) mqlO permanent magnet, g) peristaltic pump and heat exchanger for temperature control liquid and h) extruder pump and heat exchanger for sample liquid. The coordinate system designates the coordinates given by the magnet and gradient system.

The refrigerator unit is about 15 in. by 12 in. by 28 in. (exclusive of the projection of the vacuum jacket to accommodate the electronic device) it weighs about 90 lb (exclusive of the permanent magnets required for the vacuum pumps) and requires less than 100 w of electrical power. Ample space is provided for the device to be refrigerated, as can be seen in Fig. 9. 

Intermediate sodium is circulated through the shell-side of the IHX and the shell-side of the SG by two EM pumps, each located in the cold leg of the loop in the SG facility. The internal EM pumps— pumps with no moving parts that move conductive fluids by way of a magnetic field—circulate the molten sodium through the reactor core and then to the IHTS. Permanent magnet flow meters are located in the cold leg to monitor sodium flow in the loop. 

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