FloraFlex Air Bleed Valve 3/4 in (1=6/Pk)In Store Location 2: @F11 FloraFlex Air Bleed Valve The FloraFlex Air Bleed Valve (3 4 in) can be installed on any mainline to prevent air locks. When water starts to flow, air is forced out of the Air Bleed Valve. When water hits the valve, the valve closes and water flows freely through the line. This product gives you more control over the accuracy of your feedings.