I have just read this thread and I have a few thoughts, not sure if all the previous advice is clear, and if you have no previous experince with a purifier then you want to be 100% sure!!!.
If you open the bowl all the parts have locating dowels or cut outs and they must be correctly lined up on assembly. When tightening the locking ring (big round nut) that clamps the two halves of the bowl together, you should always use a "soft" hammer with a lead head to avoid damaging the bearings. The Nut has to be exactly aligned with the bowl. Both have an 0 with a line through it stamped on them and they should line up exactly when the lock ring is correctly tightened.
Because of the high speed of rotation, each bowl is factory assembled and then balanced. Consequently, if any component is changed the complete bowl has to be re-balanced for safety. If the bowl is out of balance then there can be excessive vibration, bearing failure and even disintegration of the purifier, with shrapnel flying everywhere.
If you have one bearing fail, change all the bearings on the horizonatal shaft and the vertical shaft. The vibration from the first bearing to fail is transmitted through the gears to all the other bearings and damages them. If you only replace the obviously damaged bearing you will be opening up the purifier every 10 days to change one bearing each time. Much better to change all the bearings and have no problems for a couple of years.
First thing I was always taught was after re-assembling the purifier, always turn the bowl by hand and get it spinning at a good speed then close the top cover fully for a few seconds before opening it and checking that the bowl is still turning, (just in case the bowl height is adjusted incorrectly and the bowl is touching the top cover) If the bowl has stopped, you have to investigate.
If this purifier was previously used to purify the same grade of fuel it SHOULD have the right gravity disc inside, but check with the NONOGRAM in the instruction manual just in case, if you have the wrong size disc, you will either dump good oil into your sludge tank or be pumping dirt and water into your clean oil tank.
With regard to lubrication you require a good gear oil, some purifier makers reccommend coating the gears with Molybdenum Disulphide grease, in addition to filling the sump with oil, when running in new gears. The instruction manual will give you suitable grades. Synthetic oil is better for purifiers operating at high temperatures but mineral oil is fine purifying cold diesel oil.
The general set up should be that you put your dirty oil into a "settling tank" and allow the water and dirt to settle to the bottom for a few days after it is delivered/transferred into this tank.
Then drain the sedimenbt from the tank through a drain valve at the bottom.
Next open all the oil valves from the settling tank through to the clean or service tank, except for the lever operated valve between the purifierer pump and the service tank, this should be left shut for the moment.
This type of purifier is fitted with a relief valve that allows oil to recirculate from the pump discharge back to the pump suction, so that the oil flow through the purifier can be regulated by the lever operated valve, while maintaining full flow through the positive displacement gear pump.
Next step is to light the blue touch paper and stand well back ...... (metaphorically of course)
Start the motor, if there is an ammeter for the motor it should go straight to maximum for a few moments, then fall back to maybe one tenth of the scale. The motor clutch should be slipping to reduce the load on the motor. Feel the purifier for vibration and listen for noise, if you have any, shut down the purifier and investigate.
If you have the instruction manual it wil telll you how to check that you have the correct RPM by counting the turns on the revs indicator and using a stopwatch. (If it is slow, check the hand brake is off and that the centrifugal clutch pads are in good condition.)
Once the purifier is running at the correct revs, minimum current and without any vibration or excessive noise, you can put on the water seal. You should hear a slight reduction in noise when the clutch stops slipping.
Open the water filling line on top of the purifier and you will see the water flowing through the sight glass into the bowl, let the water flow until it starts to overflow the bowl and run out of the sludge discharge at the bottom of the purifier. Close the water valve. Adding the water should also slightly damp out the noise. If you are purifying cold oil there is no need to add water continuously.
However, if you are purifying Heavy Fuel oil at 98 C or Lube oil at 95 C the water seal will evaporate and you have to top it up regularly. In SOME SPECIAL cases you leave a slight drip of sealing water into the purifier to water wash the oil, i.e. any solids that are more soluble in water than in oil will be discharged out of the sludge discharge with the excess water.
Once the bowl is full of water it will slightly damp the vibration and noise.
Finally you can slowly open the flow control lever on the pump discharge bowl inlet until you have the desired flow rate. The slower the oil flow, the longer the DWELL TIME in the purifier and the more dirt and water you will remove, especially smaller particles and those with a density close to that of the oil. The oil should displace some of the water out of the bowl, down the sludge chute but then the
If you do not have an alarm for low back pressure you can leave the discharge valve fully open.
If a pressure switch is fitted, you must first adjust it so that it will go into alarm when the discharge valve is fully open, then shut in the discharge valve until the alarm is cleared.
When you stop the purifier, you should first close the flow regulating valve, then stop the motor and put the hand brake on. The handbrake is to stop the purifier vibrating and damaging the bearings while the bowl slows down. (The bowl is usually dynamically balanced while running at constant speed, but can be unbalanced during accleration/deceleration, depending on the distribution of sludge. The brakes stops the bowl more quickly and because of it's spring loaded contact with the bowl acts as a damper.
The bowl should always be cleaned before starting the purifier because some of the sludge can become dislodged from the sides of the bowl and put the bowl out of balance.
All the best with the purifier, let us know how it goes.
It is always better to ask a stupid question than to do a stupid thing.