valves are used to prevent surge and water hammer due to flow
reversal. The specially designed springs close the discs before
flow reversal can occur. There are several types of check valves
available, such as silent wafer type, silent globe type and
double disc type. These check valves are available with Cast
Iron, Bronze, Carbon Steel and Stainless Steel Bodies.
F91 Series, which is designed to fit inside the bolt circle
of 125#/150# or 250#/300# flanges is available from 1 1/2"
through 12" pipe size. The F105 and F107 Series, which
are designed to bolt up to mating flanges, are available from
2" through 30" pipe size. The 71 Series, which is
inside the bolt circle of the same ANSI class flanges, is available
from 2" through 54" pipe sizes.
Here for Pressure Drop Charts for Check Valves