Confirm venting requirements for a grease interceptor installation under the applicable model plumbing code

Steps

1. Confirm whether the jurisdiction has adopted the IPC or UPC (or a state/local amended version), since the two model codes differ meaningfully on double-trapping and venting rules for hydromechanical grease interceptors
2. Under IPC-based logic, if the hydromechanical interceptor itself qualifies to serve as the fixture trap, confirm whether the adopted edition allows omitting a separate upstream trap and vent between the fixture and the interceptor
3. Under UPC-based logic, confirm the code does not allow the interceptor to serve as the fixture trap and requires a standard trap and vent between the fixture and the interceptor's vented flow-control fitting, with venting between the flow-control air intake and the interceptor itself typically prohibited
4. For any hydromechanical interceptor, confirm the flow control fitting itself is vented, and confirm the vent's required termination height above the flood-rim level (commonly a minimum of several inches, per the adopted code) or that it is installed per the manufacturer's listed instructions as a code-recognized alternative
5. For gravity interceptors, confirm the outlet is properly vented per the applicable chapter to prevent the interceptor from siphoning itself empty, and ensure the design avoids the interceptor becoming air-bound
6. Cross-check final vent routing and sizing against the code's general venting chapter (not just the interceptor-specific section), since interceptor venting must integrate with the building's overall vent system design