Grease Interceptor Flow Capacity

The peak fixture flow an existing grease interceptor is rated to serve.

Run the calculator

Example

You enter

Interceptor volume (gal) 1000
Retention time (min) 30
Loading factor 1.25

You get

Peak flow served 26.7 gpm

Details, formula, and sources

peak flow = volume / (retention x loading). A 1,000-gal interceptor at 30 min retention and 1.25 loading serves ~26.7 gpm; compare to the connected sinks' DFU flow to check for undersizing (PDI G101 / IPC). AHJ governs.

peak_flow_gpm = interceptor_volume_gal / (retention_minutes × loading_factor), the PDI G101 / IPC sizing relation Volume = peak GPM × retention × loading solved for the flow.

PDI G101 by name; IPC 2021 (International Plumbing Code). Section 1003.

Free read-only access at codes.iccsafe.org. PDI G101 licensed; manufacturer (Schier, Thermaco, Rockford) sizing tools free.

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

Field names used by the API: interceptor_volume_gal, retention_minutes, loading_factor, peak_flow_gpm

Retention time 30 min unless user suppliesPDI G101 by name
Loading factor 1.25 unless user supplies adjustment for high-grease useengineering practice