Versatile check valves can be installed in any position. Prevent backflow to protect your equipment. Work with both liquids and gases Use for pressure or vacuum applications. 0.18 psi breaking pressure. Install these miniature check valves with hose barbs in any position to prevent backflow. They are compatible with both liquids and gases for pressure or vacuum applications. They require 0.18 psi breaking pressure; closing pressure is 0.014 psi.