If purging with the pump on, please ensure pulse free mode is turned off.  

**Do not purge with the pump on with pulse free mode on**

Purging with the pump off is also an option, but please ensure there is back pressure while purging to avoid drawing air from the outlet side.

To purge air from the drain valve, connect a 10 mL syringe to the drain port as shown below.

Open the drain valve a half circle and pull the syringe slowly drawing ~5-6 mL.  Pulling too hard can damage the internal components or create air bubbles.  Once the line is purged, there should be a clear flow of liquid into the syringe without any air bubbles forming.