Parr Instrument Magnetic Drive - Manual (Page 3)

Parr Magnetic Drives
w w w . p a r r i n s t . c o m 3
Preface
Description
The principle operation of Parr magnetic drives pro-
vides for attaching the stirrer shaft to an inner set of
magnets. This inner assembly is then surrounded by
the drive housing that seals to the reac tor head allow-
ing pressurization without leakage. A second set of
magnets is then mounted around the sealed hous ing.
The outer magnetic assembly is then coupled to a
motor drive system to provide rotation. The coupling
force be tween the two sets of magnets permits the
shaft to turn at the rpm selected for the motor.
Parr magnetic drives are available in three torque rat-
ings: 16 in-lb, 60 in-lb, and 120 in-lb (1.8 Nm, 6.6 Nm, and
13.2 Nm). The drives are also available with two types
of shafts; one that requires a lower support bushing and
one that is “footless.” The Model number assigned to
each drive depends upon the above selection as well as
the type of connec tion used to mount the drive into the
re actor head and the type of upper cap used for connec-
tion to the overarm and motor drive system.
Related Instructions
The following Parr publications are available to
further your understanding of this equipment and its
component parts:
No. Description
201M Limited Warranty
Parr Magnetic Drive Service Instructional Video
Go to http://youtu.be/zjBw5l_yBHw to view a video
supplement to aid users with performing routine mainte-
nance on Parr Instrument Company’s Magnetic Drives.
Light Duty A1120HC/A2140HC/A2150HC Series
This is the smallest of the three drives. It is a 4-pole
model with 16 inch-pounds coupling torque. This is
normally ade quate to carry the usual stirring loads de-
veloped in a Parr “Mini” reactor and the one and two
liter bench top and floor stand models with general
purpose stir rers. The outer magnetic drive housing
measures 2¼” O. D. x 3½” high.
Heavy Duty Drives A1180HC/A1750HC/
A2160HC/A2170HC Series
This is a 6-pole model with 60 inch pounds of coupling
torque to handle most of the stirring loads arising in
Parr one and two liter, and one, two, and 5 gallon floor
stand reactors with heavy duty stirrers. The drive hous-
ing meas ures 3½” O. D. x 4½ high.
Extra Heavy Duty Drives A1180HC2/
A1750HC2/ A2160HC2/A2170HC2 Series
This is the largest of the three Parr drives. It consists of
two, 6-pole mag nets assemblies mounted end-to end
to provide 120 inch-pounds of coupling torque for use
as an alternative drive for large Parr reactors when a
strong drive is required to handle very high viscosity
loads. The drive housing measures 3½” O.D. x 6½” high.
Conversion from a smaller to a larger drive or to a
“footless” drive may require modification to the stan-
dard over/arm and motor configuration. It may require
a different head.
Note: Unless otherwise indicated, the instructions
given here apply to all of the above units.
Characteristics
Parr magnetic drives require minimal attention or
maintenance. The spe cially designed neodymiumiron-
boron permanent magnets used in these drives have
excellent temperature sta bility and can be relied upon
to operate for long periods with little or no flux degra-
dation. When properly installed, the outer rotor should
spin freely and the inner (driven) unit should follow
without slippage, providing a high torque stirring
action. The magnets in both inner and outer rotors are
epoxy bonded to their iron cores.
Care must be taken to prevent these components from
being heated above 100 °C, which would destroy the
bond ing of the magnet assemblies. To pre vent over-
heating, each magnetic drive has an attached cooling
sleeve through which a steady flow of cold water
should be fed during all vessel operations at tempera-
tures above 100 ºC. Tubing connections for flowing
water connections are provided on each sleeve, and
a 10 foot length of tub ing is furnished to connect to a
water source.