- Needle valves are designed for flow control and regulation applications.
- Some shut-off valves like butterfly valves and gate valves are used for regulation but these valves are not suitable for continuous operation in regulating duty.
- Improper continuous use of butterfly and gate valves leads to material damage and decreases operation life.
- Another feature is the control characteristics. Asymmetrical cross section change in closure makes butterfly and gate valves nonlinear control devices.