An apparatus for use in a fluid delivery system includes a housing configurable to separate a first volume of gas from a second volume of gas and an interface arranged within the housing. The interface includes a bubbler member that is fluidically wetted with a fluid via capillary action. The interface is configured to allow a gas from the first volume of gas to pass through the fluid into the second volume of gas when a pressure difference between the first and second volumes of gas reaches a first threshold level. The interface is also configured to allow a gas from the second volume of gas to pass through the fluid into the first volume of gas when the pressure difference between the first and second volumes of gas reaches a second threshold level.