Motorized Butterfly Valves for HVAC Systems
Why Motorized Butterfly Valves for HVAC?
Unlike manual valves, motorized variants allow for modulating control or on/off actuation via a 0-10V or 4-20mA signal. Key benefits include:
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Energy Efficiency: Low pressure drop reduces pump energy consumption.
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Fast Response: 90-degree rotation allows for quick shut-off.
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Bidirectional Sealing: Reliable isolation under high pressure differentials (PN16/PN25).
Technical Specifications
| Parameter | Specification |
|---|---|
| Size Range | DN50 to DN600 (2” to 24”) |
| Body Material | Ductile Iron / Stainless Steel 304 |
| Disc Material | Epoxy-coated Nodular Iron / Stainless Steel |
| Seat Material | EPDM / Viton / PTFE |
| End Connection | Wafer Type |
| Actuator Type | On/Off or Modulating |
| Control Signal | 0-10V, 4-20mA, or 2-point floating |
| Close-off Pressure | Max 16 Bar (232 PSI) |
| Ambient Temp | -10°C to +60°C (14°F to 140°F) |
Flow Coefficient (Cv) vs. Pressure Drop
For HVAC water systems, aim for a pressure drop (ΔP) of 0.5 to 2 PSI at maximum flow.
| Valve Size (DN) | Inches | Max Cv | Recommended Torque (Nm) |
|---|---|---|---|
| DN50 | 2" | 110 | 15 Nm |
| DN65 | 2.5" | 180 | 20 Nm |
| DN80 | 3" | 280 | 25 Nm |
| DN100 | 4" | 450 | 35 Nm |
| DN150 | 6" | 1100 | 60 Nm |
| DN200 | 8" | 2100 | 100 Nm |
Actuator Selection Guide
| HVAC Application | Max Valve Size | Required Torque | Actuator Speed | Signal Type |
|---|---|---|---|---|
| AHU Chilled Water Coil | DN150 | 60 Nm | 35 sec | 0-10V |
| Cooling Tower Bypass | DN200 | 100 Nm | 15 sec | On/Off |
| Chiller Isolation | DN250 | 200 Nm | 45 sec | 4-20mA |
| Heat Pump Loop | DN100 | 35 Nm | 30 sec | 0-10V |
Torque Calculation Formula
Required Torque (Nm) = (Pressure Differential in Bar) x (DN in mm) / 20
*Example: DN150 at 5 Bar differential → (5 x 150) / 20 = 37.5 Nm. Select 60 Nm actuator for a 1.5x safety factor.*
Installation Best Practices
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Upstream Piping: Allow 5x pipe diameter of straight run before the valve.
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Disc Position: Keep the disc slightly open (10°) during flange welding to prevent gasket damage.
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Actuator Mounting: Avoid mounting the actuator upside down unless rated IP67 to prevent condensation damage.
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Manual Override: Always test manual operation before powering up.
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