Vacuum Pumps
Vacuum pumps often do
not get much attention. To help the operation of your pump you should:
1.
Determine the condition of the vacuum pump oil. Take a small sample from the
pump drain in a clean container to see if there is any contamination such as
metal particles or water.
2.
Maintain a proper level of oil in the reservoir. If there is too much oil the
vacuum pump has no place to exhaust the vapors. If too little oil in the
reservoir there is no oil for sealing.
3.
Before starting any vacuum pump the pump should be preheated to at least 140°F to 160°F. That means the pump
should be started at least 30 minutes before the pump is opened to the system.
If the pump is opened to the system while the pump and oil are cold, any
contamination will stay in the pump and oil and not be exhausted.
4.
A good practice is to verify the blank-off pressure of the pump before it is
needed. The blank-off pressure is the pressure with the pump isolated from the
system. To do this a vacuum sensor will have to be installed on the pump.
•
The blank-off pressure should be at least 50 millitorr below the lowest
required operating pressure.
•
Every permanently mounted pump should have an exhaust piping drop leg that can
be drained. Any contamination exhausting from the pump will collect in the drop
leg rather than recontaminating the oil.
5.
Any visible oil around the vacuum pump is a sign that oil is leaking out. Such
a leak to atmosphere could be stealing efficiency.
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These technical tips are for use by qualified maintenance
personnel who are familiar with their specific freeze drying equipment. These
tips are intended only as general guidelines. Lyophilization equipment is
frequently custom configured and some tips may not be appropriate for all
freeze dryers. Always read and follow the directions of your equipment's
maintenance manual. If you would like to discuss one of our tech tips, please
contact Dave Clayton at 215-672-7800 ext-1376.