G200/G201 Series back check valves are specifically intended for heavy-duty in-line service at the bulk plants transfer area. The valves are suitable for LP-Gas or Anhydrous Ammonia (NH3) service. Flow moves the spring loaded poppet to the open position as soon as pressure differential is created. A soft seat construction gives tight shutoff so that piping can be blown down for maintenance. Type G201 has a built-in flow indicator mechanism, which can be used to replace sight flow indicators.