Pressure Regulator (PRV) Sizing
Size pressure reducing valves for water supply systems per UPC/IPC
Pressure Requirements
Street/main pressure
Max 80 PSI per code
Flow Requirements
Pipe Size
PRV Requirements
Recommended PRV Size
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Required Cv
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Peak Flow Demand
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Pressure Drop
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Velocity at PRV
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PRV Required?
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Note: PRV required when static pressure exceeds 80 PSI per UPC 608.2/IPC 604.8.
Typical PRV Cv Values
| PRV Size | Typical Cv | Max GPM |
|---|---|---|
| 1/2" | 2-4 | 8-15 |
| 3/4" | 4-8 | 15-30 |
| 1" | 8-15 | 30-55 |
| 1-1/4" | 15-25 | 55-90 |
| 1-1/2" | 25-40 | 90-145 |
| 2" | 40-70 | 145-250 |
Installation Requirements
- Install PRV after meter, before branches
- Provide strainer upstream of PRV
- Expansion tank required with check valve
- Pressure gauge for monitoring
- Bypass recommended for maintenance
PRV Sizing Formula
Flow Coefficient (Cv) Formula:
Cv = GPM / sqrt(dP / SG)
Where: GPM = Flow rate, dP = Pressure drop (PSI), SG = Specific gravity (1.0 for water)
Fixture Unit to GPM Conversion:
Uses Hunter's Curve method for demand estimation based on fixture count and type.