A pneumatic multiport selector valve and analytic instrument employing said valve are provided. The valve includes a base having a mounting surface configured to mount to the analytic instrument. The mounting surface has a plurality of apertures therein for coupling to flow conduits of the analytic instrument. At least one piston plate has a number of apertures therethrough. The apertures are configured to slidably receive respective pistons. Pistons are disposed in respective apertures of the at least one piston plate. A cushion layer is disposed between the at least one piston plate and the base. The cushion layer has a plurality of apertures to allow actuation gas therethrough. A plate clamps the at least one piston plate to the base.