The KNF Woulfe's Bottle is a combination vacuum regulator and trap. The thick-walled Erlenmeyer flask has a plastic safety coating and includes a bleed ventilation valve for vacuum control. Plastic fittings are for 3/8" ID tubing. The vacuum gauge reads in mbar and mm Hg. The Woulfe's Bottle is plumbed between the pump and laboratory device.

The Woulfe's Bottle allows the user to manually control vacuum performance, which is particularly useful to control a pump's flow or vacuum pressure. In applications where wet vapors and/or small amounts of liquids are transferred in a vacuum system, the Woulfe's Bottle captures potentially damaging liquid and extends pump life.