Pneumatic Water Regulating Valve Size:1''~20'' ... Cast Steel or Stainless Steel Pneumatic Regulating Valve For Water, Steam, Oil, Acid, Gas Size:DN20~ ... balancing valve core structure , little axial unbalanced force, large allowable differential pressure, good stability .Socket duplicity is good ... to such low flow resistance in surface flow ,large adjustable scope, Inherent adjustable proportion is 50:1 ...