Reduce Purge / Dry Times Maximize Vapor Exit Path With Cascade’s MAXEVAP Connection Kit! Cascade’s CVO vacuum ovens offer two different vacuum oven connection points. The standard connection is a ⅜” dia barb located at the rear of the oven. When using the standard exit point and connection size all the outgassing material must find its way out via the ⅜” dia exit hole and interior plumbing and vacuum lines. For large batch, production level processing, pumping off this smaller ⅜” diameter plumbing and lines can slow the process down.