Grease Trap Sizing
Volume from peak flow, retention, and loading factor (PDI G101).
Example
You enter
- Peak fixture flow (gpm) 50
- Retention time (min) 30
- Loading factor 1.25
You get
- Required volume 1875
- Recommended nominal 2000
Checked against published worked examples from: PDI.
Details, formula, and sources
ScopeVolume from peak flow, retention, and loading factor (PDI G101), plus the grease stored between pump-outs that IPC 2027 adds for a gravity interceptor: meals per day x pounds of grease per meal (Table 1003.3.8) x the service interval, at most 90 days, / 6.4 lb/gal.
Formula or tableVolume = peak GPM × retention time × loading factor. Recommended nominal size is the next typical commercial trap size (20 to 3,000 gal). IPC 2027 Section 1003 governs interceptor selection, and for a gravity interceptor 1003.3.11.1 adds grease storage = meals/day x Table 1003.3.8 lb/meal x service days (at most 90) / 6.4 lb/gal to the separation volume.
Source and editionPDI G101 by name; IPC 2027 (International Plumbing Code). Section 1003 (1003.3.11.1 and Table 1003.3.8 for grease storage).
Free accessFree read-only access at codes.iccsafe.org. PDI G101 licensed; manufacturer (Schier, Thermaco, Rockford) sizing tools free.
What governsEstimate. AHJ and licensed plumber / gas fitter govern. Verify against the IPC / IFGC edition adopted in your jurisdiction.
API field namespeak_flow_gpm, retention_minutes, loading_factor, volume_gal, recommended_nominal_gal
- Retention time 30 min unless user suppliesPDI G101 by name
- Loading factor 1.25 unless user supplies a job-specific factorengineering practice