ASTM A351standard CF8M Cast Steel rising stem Industrial Flanged RF 300LB Globe Valve with handle

Globe valve, also known as cut-off valve, belongs to the mandatory sealing valve, so when the valve is closed, pressure must be applied to the valve flap, in order to force the sealing surface does not leak. When the medium enters the valve from below the valve flap, the resistance to be overcome by the operating force is the friction of the valve stem and packing and the thrust generated by the pressure of the medium, the force to close the valve is greater than the force to open the valve, so the diameter of the valve stem should be large, or else the stem will occur the top of the bending of the valve stem failure. According to the connection method is divided into three kinds: flange connection, silk buckle connection, welding connection. From the emergence of self-sealing valves, globe valves, the medium flow direction is changed from the valve flap above into the valve cavity, then under the action of medium pressure, the force to close the valve is small, while the force to open the valve is large, and the diameter of the valve stem can be reduced accordingly. At the same time, under the action of the medium, this form of valve is also more tight. China’s valve “three to” had stipulated that the flow direction of the globe valve, always use the top-down. Shut-off valve open, the opening height of the valve flap, for the nominal diameter of 25% ~ 30%. Flow has reached its maximum, that the valve has reached the full open position. So the full open position of the globe valve, should be determined by the valve’s stroke.