Vacuum pumps are a necessary component of freeze dryers, controlled atmosphere glove boxes and vacuum concentrators. Labconco’s pump offering includes a diaphragm pump, rotary vane oil pump and combination pump. How do you know when you need one over the other? Let’s discuss the pros and cons of each.
Pros: A diaphragm pump is low to no maintenance. Because it is oil free, oil changes are not required. Some diaphragm pumps have PTFE-coated components, which are designed to withstand solvent and acid vapors. Newer diaphragm pumps are much quieter than old style diaphragm pumps.
Cons: The ultimate vacuum of a diaphragm pump is not enough for lyophilization, which requires an ultimate vacuum of 0.002 mbar.
Pros: A rotary vane pump pulls a deep vacuum, required for lyophilization and evaporation of high boiling point samples.
Rotary vane pumps are quieter than diaphragm pumps.
Cons: Regular oil changes are required. The oil changes can take up to 30 minutes, pulling the pump off line until maintenance is complete.
Final thought: A rotary vane pump is required for the freeze drying process because of the depth of vacuum. To extend pump life, check the pump oil for contamination and change the oil as needed.
Combination Hybrid Rotary Vane/Diaphragm Pump
Pros: A hybrid pump pulls a deep enough vacuum for lyophilization and evaporation of high boiling point solvents. The diaphragm portion of the pump purges contaminants from the rotary vane portion, inhibiting contamination of the oil. Less contamination results in fewer oil changes with less down time of the pump.
Cons: Hybrid pumps are more expensive than traditional rotary vane or diaphragm pumps and require synthetic oil for optimum performance.
Final thought: A hybrid pump is perfect for mixed solutions in a freeze dryer, including solvents and acids. Because contaminants are purged, the oil lasts longer, and fewer oil changes are needed.
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