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Calculate the volume of water or liquid inside pipes in gallons, liters, and cubic feet. Essential for plumbing and irrigation projects.
Pipe volume refers to the total amount of liquid or gas that can be contained within a cylindrical pipe. This measurement is crucial for plumbing, HVAC, and irrigation systems to determine water capacity, system charges, and flow requirements.
Understanding pipe volume helps with:
Where r is the inner radius of the pipe in inches.
Example: 1.33 cu ft × 7.48 = 10 gallons
Water weighs approximately 8.34 pounds per gallon at room temperature.
Common pipe sizes with their inner diameters and gallons per foot:
| Nominal Size | Inner Dia (in) | Gal/Foot | Gal/100ft |
|---|---|---|---|
| 1/2" | 0.622 | 0.016 | 1.6 |
| 3/4" | 0.824 | 0.028 | 2.8 |
| 1" | 1.055 | 0.045 | 4.5 |
| 1-1/2" | 1.527 | 0.095 | 9.5 |
| 2" | 2.009 | 0.163 | 16.3 |
| 3" | 3.035 | 0.372 | 37.2 |
| 4" | 4.009 | 0.650 | 65.0 |
Calculate water capacity in supply lines, estimate hot water wait times, and size recirculation pumps.
Determine system volume for expansion tank sizing and glycol mixture calculations.
Calculate water volume in standpipes and main risers for system testing.
Size mainlines and laterals, calculate fill time for zones, and estimate water usage.
A standard 1-inch copper pipe (Type M) holds approximately 0.045 gallons per foot. For 100 feet of 1-inch pipe, that's about 4.5 gallons of water.
Yes, slightly. Different materials have different wall thicknesses, which affects the inner diameter. For example, Schedule 40 PVC has thicker walls than copper, resulting in a smaller inner diameter for the same nominal size.
Water weighs 8.34 pounds per gallon. For a 100-foot run of 1-inch pipe holding 4.5 gallons, the water weight is about 37.5 pounds.
Knowing the volume of water between the heater and fixtures helps estimate hot water wait time and determine if a recirculating pump or on-demand system is beneficial.