Abstract: A valve assembly for limiting the flow of fluid into and out of a chamber, consisting of: a valve seat in a wall of the chamber, wherein fluid flows into and out of the chamber through the valve seat; a valve face engaging the valve scat, wherein the valve face is external to the chamber; and a mechanism for moving the valve face toward and away from the valve seat wherein the valve face is substantially removed from the path of fluid flow through the valve seat when the valve face is moved away from the valve seat.

Abstract: A valve assembly for limiting the flow of fluid into and out of a chamber, consisting of: a valve seat in a wall of the chamber, wherein fluid flows into and out of the chamber through the valve seat; a valve face engaging the valve seat, wherein the valve face is external to the chamber; and a mechanism for moving the valve face toward and away from the valve seat wherein the valve face is substantially removed from the path of fluid flow through the valve seat when the valve face is moved away from the valve seat.

Abstract: A multiple range variable resistor and potentiometer suitable for use in the repair or manufacture of hearing aids and other miniature applications is disclosed. The user of the device can select the desired resistance range thereby allowing one component to be used in many different applications and reducing inventory requirements. It provides increased resistance to contamination of the internal components compared to conventional hearing aid volume controls and is not damaged by over-turning of the control knob in either direction. It can be manufactured for the same cost as conventional single range potentiometers.