How does the UPC distinguish a grease interceptor from an oil separator?
Not quite. The answer is C: A grease interceptor treats fats, oils, and grease from food-service wastewater; an oil separator treats petroleum-based waste, such as from a vehicle service bay
The two devices are built around different separation behaviors: a grease interceptor relies on food-service FOG cooling and rising, while an oil separator is sized for free-floating petroleum products. Installing the wrong device for the actual waste stream undersizes the separation the fixture is supposed to provide, regardless of which code governs the installation.
Reference: UPC 2021 §1014.1; §1017.1; Chapter 2 — Grease Interceptor (Grease interceptors vs oil and flammable liquid interceptors)
Checked against the official text
Checked against the 2021 UPC text. Washington's exam is written against the 2015 edition, which we have not read for this section, so confirm it against your 2015 book.
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