Abstract

A cushioned check valve includes a flow channel with an inlet, a check valve, and an outlet. Bypass channels connect the outlet, a cylinder containing a piston, and the inlet. The piston is biased toward a first end of the cylinder by a diaphragm and a hermetically sealed gas volume containing a compressible gas, blocking the bypass channels. When the fluid pressure in the outlet exceeds a nominal operating range, the piston moves toward a second end of the cylinder until the fluid pressure acting on the piston is equalized by the piston bias, and fluid flows through the bypass channel. Once the fluid pressure and piston bias are equalized, the piston returns to a position blocking the bypass channels.