Parr Instrument 6755 - Manual (Page 40)

9
Maintenance
P a r r I n s t r u m e n t C o m p a n y 38
C
HAPTER
9
Maintenance
Examine the rotating cell periodically for leaks by closing the cell and submerging the empty bell
in a beaker of water for a period of time comparable to a complete run in the calorimeter. If water
migrates into the sealing area between the PTFE dish and the glass bell, the seal is deteriorating
and the 126C PTFE dish should be replaced.
After one hundred hours of operation, or once each year, apply one drop of instrument oil or
household oil to the motor bearing, and one drop of oil to the bronze stirrer shaft bearing. Be sure
to remove any excess oil that may appear at the bottom of the shaft.
There is no routine maintenance recommended for the 6772 Calorimetric Thermometer.
Fuses
The replacement of protective fuses for the 6722 Calorimetric Thermometer should be performed
by qualifi ed personnel.
WARNING:
For continued protection against possible hazard, replace fuses with same type and rating of fuse.
Part No. Type Specifi cations
139E23 Main line protective fuses Fast-Act 15 Amp, 250VAC
1641E Fuse F1– stirrer fuse Fast-Act 1 Amp, 250VAC, 5 x 20mm
The stirrer fuse is located on the A2140E I/O board located inside the instrument. To gain access
to the inside, fi rst disconnect the power cord from the rear of the unit. Remove the two screws at
the upper rear of the unit that secure the front cover. Pry up on the back lip of the cover and care-
fully hinge it forward. Make sure that the cables attached to the front portion of the cover do not
become stretched or disconnected. Follow this procedure in reverse order to re-secure the front
cover.
Conversion from 6755 to 6725
All parts needed for this conversion are provided in a 6729 Conversion Set. Installation should
proceed step-wise, as follows:
1. Remove the A1195E2 Thermistor, A130C Cell and A137C Pulley Assembly from the calorimeter
cover.
2. Remove the 123C Dewar and 122C Ring from the air can. Attach the A137C Pulley Assembly
with 3/8” I.D. washer from the solution calorimeter cover to the bearing tower on the A120C3
Cover furnished with the conversion set. Attach the A72C2 Impeller Assembly to the drive
shaft. Then place the cover assembly on the air can so that the cover is centered in the air can
and the alignment slot straddles the alignment pin.
3. Replace the drive belt, attaching it fi rst to the drive pulley and then onto the driven pulley.
The calorimeter is now ready to operate as a Semi-micro Oxygen Bomb Calorimeter, using in-
structions furnished with the 6729 Conversion Set.