Gas Leak Rate (Orifice)

Estimated leak rate from orifice diameter and upstream pressure.

Run the calculator

Example

You enter

Orifice diameter (in) 0.05
Upstream gauge pressure (psi) 0.25
Gas natural_gas
Discharge coefficient 0.7

You get

Leak rate 3.15 ft^3/hr
Orifice area 0.00196 in^2

Details, formula, and sources

Orifice-flow leak estimate Q = 3550 * c * A * sqrt(dP / SG) (scf/h), the Spitzglass-coefficient form using specific gravity, matching the compute. Estimation only, not an authoritative leak-rate calculation.

Classical fluid mechanics; orifice coefficient typical from public engineering references.

NIST fluid-property tables free at nist.gov.

Estimate. AHJ and licensed plumber / gas fitter govern. Verify against the IPC / IFGC edition adopted in your jurisdiction.

Field names used by the API: orifice_diameter_in, upstream_psi, gas, c, leak_rate_cfh, orifice_area_in2

Discharge coefficient Cd 0.61 sharp-edged orifice unless user suppliesengineering practice
Gas density at standard conditions from data/plumbing/gas-pipe-capacity.jsonengineering reference