Gate valves(Ball Screw operation) The Ball-Screw operation gate valve was developed for large-bore applications,to provide manual operation at full working pressure with remakably low opening torque.The design eliminates the need for gear-type torque multipliers,and results in quicker,safer operations. The Ball-Screw operation gate valve shares the basic features of the "LS"series:a slab gate,patented seat seal,non-elastomeric stem seals,and metal-to-metal sealing.However,the Ball-Screw operation gate valve has a lower balancing stem and unique ball Screw mechanism Size:3-1/16",4-1/16",5-1/8",7-1/16" WP:10,000psi,15,000psi Temperature:L U,PU Mat's:AA-FF PSL:1-4 PR:1-2 Honorary Certificate Our products have been ISO9001 certified and attained API 6A,6D,API 7,7K,and API 16A&16C approvals of American Pertroleum Insitute.All products are fully designed and manufactured in accordance with API,ANSI,GB(national standards)and SY(industry standards)standards.