[QUOTE=ian parkes;241600] i have just picked up a small second hand air floor SIB . Its a waveline in PVC with the usual screw in valves .
Is it the type of Halkey Roberts Valve, a 2 part valve. upper & lower screw type ?
"The valve in the air floor is leaking around the outside where it clamps in . i have taken it our and the fabric is fine and the valve appears to ok on the rim where it clamps the fabric but it still leaks when i refit it".
Is the fabric around the floor where both pieces clamps even ? There is a tool to adjust air valves, have you made the adjustment only by hand ? If the air leak persists, try a new valve if available or put some pvc glue around the collar rim seals (where it clamps) and adjust tight as possible, let dry overnight.
Last issue are the rim seals of both parts (upper & lower) in good shape or any of them has a crack, missing part or whatever, if so replace defective part. (See pic example)