Valve assembly for the remote control of fluid flow having an automatic time delay

Abstract From the Canadian patent

A downhole float valve is normally closed by a spring or other means of applying axial pressure until sufficient pressure of drilling fluid from the surface opens the valve. The valve stem includes a dashpot type housing secured thereto and moving within a fluid filled cylinder. When the valve opens the movement is controlled by a one-, way valve in the housing giving a relatively rapid opening. When pressure of the drilling fluid from the surface is removed, the pressure on the underside of the valve typically assisted by the spring, closes the valve. An adjustable bleed passage in the housing delays this closing for a pre-determined time thus allowing the pressure on the underside of the …