The BS750 Fire hydrant is normally used by the fire service, it is made of ductile iron or cast iron according to BS 750 .
Typical technical data :
1.Dimentions according to BS750 Type 1
2.Flange drilling to EN1092-2:1997 
3.Copper outlet : 3.1 Internal diameter :64mm
  Type of threads: V thread
  Threads per 25.4mm : 5 1/3 nos