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.