Gas Pipe Sizing
BTU capacity by pipe size, length, gas type.
Example
You enter
- BTU load (BTU/hr) 100000
- Pipe length (ft) 50
- Gas natural_gas
You get
- Required capacity 97.1 ft^3/hr
- Recommended size 0.75
Details, formula, and sources
Spitzglass low-pressure formula Q = 3550 * sqrt(d^5 * dP / (SG * L * (1 + 3.6/d + 0.03 d))) sizing a SINGLE run of the entered length -- it picks the smallest listed diameter whose Spitzglass capacity meets the load. This is a single-segment estimate, NOT the full IFGC 2021 Section 402.4 / Tables 402.4(1)-(36) longest-length network method, and does not implement the Weymouth equation; a multi-branch system is sized on the single longest run to the most remote appliance, which the AHJ and the tables govern.
IFGC 2021 (International Fuel Gas Code) / NFPA 54. Section 402.4 and capacity tables.
Free read-only access at codes.iccsafe.org. NFPA 54: Free read-only access at nfpa.org/freeaccess.
Estimate. AHJ and licensed plumber / gas fitter govern. Verify against the IPC / IFGC edition adopted in your jurisdiction.
Field names used by the API: btu_load, length_ft, gas, required_cfh, recommended_size
- Pressure-drop allowance 0.5 in WC (low-pressure) / 1.0 psig (medium-pressure) unless user suppliesIFGC 2021 Section 402.3
- Specific gravity 0.60 natural gas / 1.50 propanedata/plumbing/gas-pipe-capacity.json