304 Stainless Steel Pressure Resistant Internal Threaded Gate Valve Z11W-16p DN25

https://bodavalve.en.made-in-china.com

Product  Description 
 

The opening and closing part of a threaded gate valve is a plug shaped valve disc, with a flat or conical sealing surface. The valve disc moves in a straight line along the centerline of the fluid. The movement form of the valve stem can be either the lifting rod type (valve stem lifting, handwheel not lifting) or the lifting rotating rod type (handwheel rotates together with the valve stem to lift, and the nut is installed on the valve body). 

The corrugated tube shut-off valve is only suitable for full open and full close, and is not allowed to be adjusted or throttled.

Thread gate valves, internal thread gate valves, high-pressure gate valves, and corrugated tube globe valves are forced sealing valves. Therefore, when the valve is closed, pressure must be applied to the valve disc to force the sealing surface to not leak. 

When the medium enters the valve body from below the valve disc, the resistance that needs to be overcome by the operating force is the friction force between 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 larger, otherwise the failure of the valve stem top bending will occur. In recent years, since the emergence of self sealing valves, the medium flow direction of the shut-off valve has shifted from above the valve disc to the valve chamber.

At this time, 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 correspondingly reduced. At the same time, under the action of the medium, this type of valve is also relatively tight. 

The "three modernizations" of valves in China once stipulated that the flow direction of shut-off valves should be from top to bottom.

When the internal threaded gate valve is opened, the opening height of the valve disc is 25%~30% of the nominal diameter, and the flow rate has reached its maximum, indicating that the valve has reached the fully open position. So the fully open position of the shut-off valve should be determined by the stroke of the valve disc.