The typical applications of Butterfly Valves are: vacuum services, slurry services, high-temperature, high-pressure and steam services, compressed gas or air applications and cooling water, gas, air and fire protection.
Butterfly Valves are used to regulate and control, throttle the flow.
All valves are designed to meet a designated internal permissible leak rate standard (FCI/ANSI). There are six (6) permissible leak rates or Classes numbered 1 through VI. The higher the leak rate number, the lower permissible internal leak rate.
Identifying the permissible internal leak rate for a valve has to be one of the top priorities when choosing the correct valve. A valve with a high leak rate, will cause excessive wear. The valves with a high leak rate will internally pass more medium and result in premature valve failure.
There are six different seat leakage classifications as defined by ANSI FCI 70-2.