How to Vent (Dry Flush) Your Oil-Free Vacuum Pump

Keeping your oil-free vacuum pump in good shape is easy! Venting (also called “dry flushing”) your pump after each batch helps remove moisture and keeps your pump running smoothly.

Automatic Venting (Most Common)

If you set up your freeze dryer with an oil-free pump during the first installation, you’re all set!

Just select “Defrost” at the end of your batch.

Your machine will automatically purge (vent) the vacuum pump for you, remember to keep the door open during this process.

For more details, see page 21 of the Owner’s Manual.

Manual Venting (If Your Software Doesn’t Support Automatic Purge)

If your freeze dryer doesn’t have the latest software, you may need to vent your oil-free pump manually. Here’s how:

What You’ll Need

A paper towel (to catch any water from the pump’s exhaust port)

Steps

Turn Off the Pump
Unplug the pump’s power cord so it’s completely off.
Disconnect the Vacuum Hose
Remove the vacuum hose from the pump. This keeps water from flowing back into the pump.
Plug the Pump Back In
Plug the power cord back into an outlet. (The pump can be noisy, so choose a spot where the sound won’t bother you.)
Run the Pump
Turn the pump on and let it run for 5–7 minutes. This pulls air through the pump and dries out any moisture inside.
Catch Any Discharge
Place a paper towel under the pump’s exhaust port. You might see water or other liquid come out—this is normal.

Why Venting Matters

Venting your oil-free pump after every batch helps prevent rust, keeps the pump quiet, allows it to draw a deep vacuum, and extends its life.