Large-diameter cut-off valve closed difficult problem solving methods
How to solve the large-diameter globe valve closed difficult problem
In the daily use of large diameter cut-off valve, the user is often reflects a problem, namely large diameter globe valves are used for pressure differential big media, such as steam pressure, and high pressure water with work, as it is often difficult to close, no matter how hard, he always finds that there will be shut, it is difficult to shut, leakage phenomenon caused by this one problem is the reason of the valve and structure design of the limit of the output torque.
The average adult level limit output force for 60-90kg, depending on different constitution.
Generally the globe valves for low flow design, when people into higher closing valves, human level, promoting the handwheel rotating disc downward motion, realize closed, then need to overcome three aspects, namely, the combination of:
1) Fa; axial thrust Fa,
2) Fb; with stem packing friction Fb,
3) Fc stem and disc core contact friction Fc
Total moment∑M=（Fa+Fb+Fc）R
Can see caliber, axial thrust is bigger also, when top to closed, axial thrust is almost close to actual pipe roof pressure (P1 - by closing the hundredth P1, P2 P2 = 0 DN200mm as a globe valves for 10kg/m2, the steam pipe is only first close the axial thrust Fa = 10 top x PI, and closed 3140kg = r2 needed for the horizontal circumference, already close to normal = kg body can output level limit, so the circumference of force by a man in the condition is fully closed the valve is very difficult. Certainly some Suggestions will be this kind of valve factory installed reversed, solve the difficult problem of closed, but again after the close to the open problems.
In view of the above questions, we design developed with balanced disc pressure compensation structure of dual disc structure, thoroughly solve the above problem, realize two-way operation is very compact, very tight seal, and solve the boot pipeline caused by excessive preheating bend pipe welding or part deformation and cracking phenomena.
