4) the use of pneumatic rack and pinion brass angle valve piston and valve implementing agencies --- Direct Connect, to simplify the structure; sensitive rack and pinion rotation, back to poor little action and reliable;

     5) the implementation of adequate institutions to overcome the pressure difference --- torque, friction torque, there is ample room to move freely;

     6) through media, streamlined design --- to prevent the trap and improve the reliability of action;

     7) to reduce friction spool brass ball valve spool --- to further improve, the valve seat life.

     4.4, performance indicators and the main parameters

     Model: Pneumatic ZSRH, electric (electronic) ZDRH; DN: DN20 ~ 400; nominal pressure: PN116 ~ 32; flow characteristics: approximation of the number of linear approximation; adjustable range: R = 100 ~ 200; leakage rate : 1 × 10-6 ~ 1 × 10-7; allow pressure: [Δp] ≤ PN; operating temperature: - 60 ℃ ~ 600 ℃.