Operating Instructions for Parr Magnetic Drives
Parr magnetic drives provide reliable systems for driving the internal stirrer in Parr pressure reactors using completely enclosed magnetic couplings with no rotating seals.
Servicing the Magnetic Drive
All rotating parts in Parr magnetic drives are self-lubricating and do not require servicing during normal operation. It is advisable, however, to check the drive from time to time for any evidence of leakage into the confined space between the inner and outer rotors. This can be done without removing the drive from the bomb head and does not require complete disassembly. To inspect the drive:
a. Remove the four socket head screws located near the top of the outer housing and remove the top cover from the housing. This will expose the top of the plug which aligns the inner rotor and carries the principle o-ring seal.
b. Unscrew the plug, using a 264AC5 face spanner inserted into the two holes at the top of the plug while holding the rotor firmly with a 264AC3 or 264AC4 pin spanner inserted into one of the holes at the bottom of the assembly above the cooling sleeve. With the plug removed, the sleeve bushing and thrust washer at the top of the rotor will be exposed.
c. Check for any evidence of leakage past the o-ring seal. If vapors from the reactor have produced solid deposits in or around the rotor housing, the deposits will have to be removed to keep them from destroying the guide bushings or jamming the rotor. If cleaning is not required, replace the plug and close the drive as instructed in (g) below.
d. If cleaning is required, the motor can be removed without removing the entire drive from the bomb head. To remove the rotor: Unscrew and remove the stirrer shaft from the underside of the bomb head. Then push the rotor upward and out of the housing using the stirrer shaft or other suitable rod inserted through the shaft opening. In the larger magnetic drives, the rotor can be pulled out of the housing by screwing the stirrer shaft into a threaded socket at the top of the rotor and pulling on the shaft.
The inner rotor is a laser-welded, sealed unit which should require no maintenance, but it can be damaged by overheating. With the rotor removed, it may be advisable to replace the three sleeve bushings which guide the inner rotor. Two of these, plus a spacer, are located deep in the lower shank. The third sleeve bushing is held in the top plug. Although these bushings can be pulled out with a wire hook or scribe, removal is much easier using a specially designed bushing removal tool (Parr Part Number ____). Simply screw the threaded end of the removal tool into the plastic bushing until it is firmly engaged, then pull the bushing out of the shank. The spacer between the two bushings should slide out freely.
When replacing the sleeve bushings in the lower shank, slide the parts into place carefully and be sure to separate the bushings with a spacer. When properly installed, the top of the upper bushing should be flush with the bottom of the rotor chamber. A specifically designed bushing insertion tool is available for this operation (Parr Part Number ______). Using the insertion tool, slide a bushing onto the end of the tool with the longest shank, then insert the tool with the bushing into the opening in the rotor chamber and push it down until the shoulder on the tool strikes the bottom of the chamber. This will position the bushing properly. Then drop the spacer into the opening and use the short end of the installation tool to insert the upper sleeve bushing, again pushing the tool downward until it strikes the bottom of the chamber.
After cleaning the rotor and the chamber, install the rotor as follows:
e. Set the lower thrust washer into position so that it will be available to cushion the rotor if it should accidentally slam into the bottom of the chamber.
f. Lower the rotor into the chamber slowly, but be prepared to resist the strong pull of the outer magnets during this operation. Use the same rod employed when removing the rotor to resist the strong pull during assembly.
g. Replace the upper sleeve bushing and the o-ring in the top plus; insert the upper thrust washer; lubricate the threads with 424HC2 anti-seize lubricant and screw the top plug into place. Then replace the top cover and secureit with the four socket head screws.
Servicing the Outer Drive
The outer drive is supported by two high quality aircraft type sealed ball bearings which do not require lubrication. Any oil leak or noise from the bearing will indicate that the seal or the bearing has failed and the bearing must be replaced. To disassemble the outer drive:
a. Remove the four socket head screws located near the top of the outer housing; then lift the cover from the housing to expose the upper snap ring. Peel the snap ring out of its groove with a small screwdriver; slide it upward and remove it.
b. Take a firm grip on the drive housing and pull it upward to separate the outer assembly from the inner rotor. The upper and lower bearings may come out with the housing. If not, remove them at this time.
c. Peel the lower spiral snap ring out of its groove with a small screwdriver to release the outer assembly from the inner stem.
To reassemble the outer drive:
d. Slide the lower spiral snap ring back into its groove; then slide the lower ball bearing onto the housing. The magnets probably will hold the bearing at the middle of the housing.
e. Slide the outer drive assembly over the rotor, thereby pushing the lower bearing down against the lower spiral snap ring. Hold both parts firmly during this step so that the magnets do not slam the outer drive into place.
f. Insert the upper wave spring into its groove in the outer drive housing and slide the ball bearing into place against the wave spring, then anchor the bearing by pushing the retaining snap ring downward until it snaps into its groove above the bearing.