First, the national standard globe valve introduction

GB stop valve is a mandatory sealed valve, so the valve is closed, the pressure must be applied to the valve to force the sealing surface does not leak. When the medium from below the valve into the valve, the operating force needed to overcome the resistance is the valve stem and packing friction and the thrust generated by the media pressure, off the valve force than the valve open, so the valve stem The diameter should be larger, otherwise it will happen valve stem bend. In recent years, from the self-sealing valve appears, the flange of the media cut off the valve to change from the top of the valve into the valve chamber, then under medium pressure, the valve closing force is small, and open the valve force, valve The diameter of the rod can be reduced accordingly. At the same time, in the medium, this form of stainless steel pneumatic valve is also more stringent.