A valve for selectively sealing and unsealing an opening in a bladder is disclosed. The valve includes a flange for mounting the valve around the opening in the bladder, a valve seat supported on the flange, and an air passageway. A spring plate is supported on the flange and spaced from the valve seat. A floating valve disk is provided between the valve seat and the spring plate for movement towards and away from the valve seat to seal and unseal the opening in the bladder. A spring is provided to bias the floating valve disk towards the valve seat. Deflation lugs are provided to hold the floating valve disk away from the valve seat against the force of the spring. The floating valve disk is free to pivot but is prevented from pivoting to such an extent that movement of the floating valve disk is impeded as by binding.