Pieces when gate valve gate opening in more than 10%, axial force of the gate valve gate, the gate valve gate operating torque.
When the valve opening of the door below 10%, due to the throttle fluid, the pressure difference before and after in the gate valve gate increase.
The differential pressure effect on the gate, makes the valve rod larger axial force is needed to drive the gate, so in this range, gate valve operating torque of the door change is bigger.
Flexible disc gate valves door, close to closing the required operating torque is bigger than the rigid disc.
Gate is closed, because of the sealing surface sealing way is different, can produce different situations.
For automatic sealing gate door (
Including flat gate valve door)
, the valve is closed, the sealing surface of the disc is right for the valve seat sealing surface, is the full open position of gate door.
But this position under the condition of gate door operation is unable to monitor, so in actual use, is the gate door close to dead point position as the gate door seated position.
Thus, automatic seal gate valve gate location is fitted according to the location of the damper (
For mandatory seal gate valve gate, closed gate must be made to the pressure on the valve seat.
This pressure can guarantee between the disc and the valve seat sealing surface strictly seal, is mandatory seal gate valves door sealing force.
The sealing force due to the valve stem nut with self-locking will continue to do.
Obviously, in order to provide sealing force to ram, the valve stem nut torque than the valve gate torque in the process of operation.
Thus, for mandatory seal gate valve door, seated position by the valve stem nut torque size to determine.
Gate valve after the door closed, because the media or the change of environmental temperature, thermal expansion of the gate valve gate component can make the pressure between disc and the valve seat, reflect on the valve stem nut, for the open gate door difficult again.
So, open the required torque than the closed gate valve gate valve gate the required torque, in addition, for a pair of sealing surface contact each other, the static friction coefficient is larger than the kinetic friction coefficient between them, to make them from static state to produce relative motion, to exert greater force to overcome the static friction force.
Due to changes in temperature, pressure, between the sealing surface to overcome the static friction force is bigger, so that the open gate valve door, the torque exerted on the valve stem nut sometimes increases a lot.
Gate valve gate torque reference table (nominal diameter
Nominal pressure (
0 moment (