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LEMDSR
High Torque Magnetic Drives for Stirred Reactors LEMDSR
All stirred reactors are equipped with a magnetic drive to provide a trouble-free linkage to an internal stirrer, thereby avoiding the leakage problems which sometimes arise with a packed gland stirrer drive. With a magnetic drive there are no rotating seals. The drive turns freely and the system remains gas-tight, permitting long, continuous runs at pressures up to 5000 psi (345 bar) with little or no attention to the seal and drive.
Drives are assembled with specially designed permanent magnets which have excellent temperature stability and can be depended upon to operate for long periods with little or no flux degradation. Magnets for the inner rotor to which the stirrer shaft is attached are enclosed in a stainless steel (or other alloy) housing, permanently sealed by welding and supported by graphite-filled, PTFE bushings to provide a long life, chemically inert stirring system. Magnets for the outer drive are also fully enclosed and supported by twin, high quality sealed ball bearings for smooth operation and long life. A water cooling sleeve attached to each drive protects the components from excessive heat arising from the reactor.
Significant progress was made in recent years in both magnetic materials and magnetic coupling design. Company uses neodymium-iron-boron magnets with 25% more coupling force than samarium-cobalt magnets. With very few exceptions involving gear reduction drives, the magnetic stirrers fitted to reactors have higher coupling torques than the stall conditions of standard motors. Today magnetic drives are used with confidence for high viscosity polymerization reactions.
Magnetic drives are supported with three graphite-filled PTFE bushings and quality internal ball bearings. They routinely deliver 2000 hours of operation without service.
Four Sizes
Magnetic drives are made in four sizes, designed to match the full range of reactor sizes and to provide alternate drives for high viscosity loads, higher stirring speeds and other special requirements. Each drive is assembled in a sealed housing which threads directly into the reactor head. See the Magnetic Drive Series table below for specifications.
The General Purpose and Heavy Duty models are the standard units normally furnished with the reactor sizes listed in the adjoining table. The Extra Heavy Duty model is a special high torque drive intended primarily for heavy loads and high viscosity applications. When it is used to replace a standard drive, the standard motor and drive system may have to be modified to provide the higher torque which the Extra Heavy Duty drive is capable of transmitting.
The Series 5500 Compact Reactors have a smaller magnetic drive that is intended for low viscosity applications.
Two Styles Available
Copany offers a choice of two styles of magnetic drives. The first operates with small diameter stirrer shafts which require a lower support bracket or “foot” bearing to stabilize the stirrer shaft. These drives are intended for high speed stirring for applications involving liquid-liquid or gas-liquid mixing.
The second, footless magnetic drives employ a larger diameter stirrer shaft designed to operate without this lower support bracket or “foot” bearing. These drives were originally designed for digesting ores where the abrasive solids would get caught in the PTFE foot bearing and wear away the stirrer shaft. They are also recommended for slower-speed mixers such as the anchor, paddle, or spiral stirrers. It is also important to select the appropriate motor which can handle the increased drag associated with the larger diameter shafts.
Magnetic Drive Coupling Torque
(in-lb)*Shaft Diameter
(inches)Foot Bushing
Required?
(see text above)Ordering Guide
AbbreviationSupplied as Standard
Mag Drive on Reactors
with these Volumes:General Purpose 16 3/16″ Yes M 25mL to 2L 16 3/8″ No — “Footless” FMD1 Heavy Duty 60 3/8″ Yes HD 1gal to 5 gal 60 5/8″ No — “Footless” FMD2 Extra Heavy Duty 120 3/8″ Yes XHD 1gal to 5 gal 120 5/8″ No — “Footless” FMD3 Compact 2.5 3/16″ Yes N/A 5500 Compact Reactors *1 in-lb = 0.11N-m
| Model | LEMDSR |
| Brand | LabEquipx |
