TL;DR
A drip at the shaft seal housing means the mechanical seal faces are worn or the flush supply has failed. Stop the unit, check flush flow, and replace the seal.
What you might see
- product or solvent dripping from bowl shaft area
- seal flush flow meter reading low
- product contamination in seal flush return
- burning smell near shaft seal housing
Likely causes
Seal face wear from abrasive solids or dry running
Flush supply pressure too low or flush line blocked
O-ring degradation from solvent incompatibility
Improper spring load from incorrect installation or wear
Required tools
- LOTO kit
- Seal replacement kit for this centrifuge class
- Calibrated torque wrench
- Chemical-resistant gloves
- Flow meter or rotameter
Safety first
- Process solvents in pharma centrifuges are often flammable or toxic. Confirm safe atmosphere with a gas detector before opening the bowl.
- The seal flush circuit may be under pressure. Isolate and depressurize before disconnecting any fittings.
- Wear solvent-rated gloves and face protection when draining or disassembling a wet bowl.
Procedure
- 1
Stop the centrifuge. Lock out and tag out the drive disconnect and the seal flush supply valve.
- 2
Verify the seal flush supply flow rate and pressure at the flush inlet. Compare to the specified minimum.[1]
- 3
Check the flush return line for product color or cloudiness indicating face leakage across the inboard seal.
- 4
Drain and flush the bowl. Confirm the product is fully purged before disassembly.
Warning: Solvent-service centrifuges may retain flammable liquid in the bowl cavity. Confirm atmosphere safe before opening. - 5
Remove the bowl, spindle, and seal housing per the general disassembly sequence.
- 6
Inspect seal faces for chips, scoring, or thermal cracking. Replace both faces as a matched set.
- 7
Inspect all O-rings for swelling, cracking, or compression set. Replace with material compatible with the process solvent.
- 8
Reassemble and confirm flush flow is restored before starting. Run a short trial spin and check for leaks.
Sources
Alfa Laval Alfa Laval AFPX / Foodec Centrifuge general technical documentation, Alfa Laval
Alfa Laval AFPX / Foodec centrifuge general mechanical seal replacement and flush circuit procedures (general)
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