Parr Instrument Magnetic Drive - Manual (Page 6)

Parr Magnetic Drives
P a r r I n s t r u m e n t C o m p a n y 6
Removing and Installing Mag netic Drives with
Flat Gasket Seals
These magnetic drive assemblies can be removed
from the vessel head using the appropriate pin span-
ner wrench fur nished with the apparatus (See Table on
Page 8). First, unscrew the stirrer shaft from the inner
rotor, then insert the pin spanner into one of the holes
below the outer jacket and unscrew the drive as sembly
while holding the vessel head firmly. The cooling
sleeve can be held stationary when unscrewing the
drive from the head. The drive is sealed into the head
with a gasket which usually will remain in the head
when the drive is removed.
If the gasket appears to be in good condi tion, it can be
reused. If it is question able, replace with a new one.
Apply a lib eral coating of anti-seize lubricant to the
mounting threads of the drive body before screwing
the drive into the head. Tighten the drive firmly with
the pin spanner and screw the stirrer shaft into the
inner rotor to complete the assembly.
Removing and Installing Mag netic Drives with
Olive Seals
To remove these magnetic drive assemblies, unscrew
the stirrer shaft, then hold the bomb head firmly and
use the 739HC (1-5/16”) wrench furnished with the
appara tus to remove the drive by unscrewing the
gland nut located below the cooling sleeve. The cool-
ing sleeve can be held stationary during this operation
to clear the nearby fittings as the drive is re moved.
These drives are sealed into the head by compression
from the gland nut onto a tapered 663HC olive. There
is no gasket in this gland. Remove and clean the olive
whenever the gland is removed.
To install these drives, coat both sealing faces on the
663HC olive with anti-seize lubricant and set the olive
squarely in the head. Lubricate the threads on the
stem of the magnetic drive and screw the 664HC gland
nut onto the stem as far as it will go; then back it off
one-quarter turn. Lubricate the threads on the gland
nut and screw the drive assembly into the head, being
careful to maintain the one-quarter turn relationship
between the stem and the nut. Tighten the nut firmly
to complete the connection. Screw the stirrer shaft into
the drive from the underside of the head and check the
assembly by spinning the drive by hand. The stirrer
should turn freely without binding.
Servicing the Cooling Sleeve
The cooling sleeves used on Parr mag netic drives have
two O-rings which seal the sleeve onto the stem of the
drive housing. These O-rings will have to be replaced
after long service or after ex cessive heating with no
water flowing through the sleeve . To replace the O-rings
it will be necessary to remove the drive assembly from
the head as de scribed above. After removing the drive,
rotate and pull off the cooling sleeve after removing the
clip ring, if present. The O-rings can now be removed
from the sleeve, but be careful not to scratch or damage
the O-ring grooves. Clean any accumulated lime de-
posits from the sleeve and insert new O-rings into the
grooves; then moisten the O-rings and slide the cooling
sleeve into place on the drive stem. The drive can now
be rein stalled in the head as described above.
Older Models
All series 4520 and 4530, one and two liter reactors built
before November, 1985 were equipped with A1120HC2
and A1120HC3 magnetic drives respectively. These
older models are similar to the present A1120HC style
except they have different mounting threads and dif-
ferent shaft lengths for attachment to the for mer 229HC
style head. All instructions given here for the current
A1120HC drive apply to these older models as well.
Installing the Stirrer Shaft on a Footless
Magnetic Drive
Normally the stirrer shaft is simply screwed into the
inner magnetic rotor housing from the underside the
stirrer housing. There is no interference in magnetic
drive Series A1120HC, A1180HC or A1750HC to cause a
problem.
In the Series A2140/50HC, A2160HC and A2170HC
footless magnetic drives it is pos sible to trap the thrust
washer between the shoulder machined on the shaft
and the inner magnetic rotor housing. If this happens
there will be a large amount of run out in the shaft or
the shaft will be too long for the cylinder. This can be
prevented by first removing the outer magnetic drive
housing and the plug. Then use the shaft to push up
from the bottom the inner magnetic rotor housing and
installing the thrust washer on the stirrer shaft below
the machined shoulder so there is no interference from
the thrust washer. Screw the stirrer shaft and the inner
magnetic rotor housing parts together and reassemble
the rest of the magnetic drive.