How to find the right Control Valves AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Control Valves
- Cv sizing
- Size by required Cv at design flow and pressure drop, not by pipe size. Oversized control valves operate near closed, which causes hunting and seat wear.
- Flow characteristic
- Equal-percentage for most process and HVAC coil loops, linear where valve pressure drop dominates the system. The characteristic determines how controllable the loop is.
- Actuator signal and fail position
- Match the control signal (4-20 mA, 0-10 V, floating, on/off) and specify fail-open, fail-closed or fail-in-place. Fail position is a safety decision.
- Seat leakage class
- Specify the ANSI/FCI 70-2 leakage class (Class IV, V or VI) needed for tight shutoff. Standard control valves are not bubble-tight.
- Close-off pressure
- The actuator close-off rating must exceed the maximum differential pressure across the valve. An undersized actuator cannot shut against pump head.
Brands that matter
- Fisher (Emerson): Industrial process control valves.
- Belimo: HVAC characterized control valves and actuators.
- Samson: Process control valves.
- Flowserve (Valtek): Heavy industrial control valves.
- Siemens: Building automation valves and actuators.
- Honeywell: HVAC zone and control valves.
What to avoid
- Sizing the valve to line size
- Using on/off zone valves where modulation is required
- Actuators without a stated close-off rating