No. 300 with Buna-S

The No. 300 contains a silicone treated Buna-S rubber poppet on a brass stem, designed to open easily and be more durable than O-rings.  Being flexible, they cannot leak.  Used as an all purpose check valve for multiple applications, including cold water, ethylene and glycol.
Specifications Price List Contact Us
300 Series Size Availability
  1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" *3" **3"
300 Y Y Y Y Y Y Y Y Y
375 Y Y Y Y Y Y Y Y Y
385 Y Y Y Y Y Y Y Y Y
351     Y Y Y Y Y   Y
352     Y Y Y Y Y   Y

* New valve:  Standard female threads on both ends, Cv Factor of 185
** Original valve: 2-1/2" valve body with 3" male threads, Cv Factor of 68.5