Plumbing Traps, Interceptors, And Separators — Flashcards

Plumbing traps, interceptors, and separators are critical components designed to protect sanitary drainage systems by sealing out sewer gases, catching debris, and separating harmful substances like grease or oil. Traps (e.g., P-traps) use water seals at fixtures, while interceptors (e.g., grease traps) prevent waste from entering the sewage system. 

Plumbing Traps (Water Seal Traps)
Traps are U-, S-, or J-shaped pipe fittings installed below fixtures to retain a small amount of water. This water seal creates a barrier, preventing foul sewer gas and vermin from entering the building. 

P-Trap: Commonly used for sinks, lavatories, and showers.
Floor Trap (Nahny Trap): Set in the floor to receive wastewater from bathrooms, sinks, and showers.
Interceptor Trap (Disconnecting Trap): A large trap used on building sewers to block sewer gas from entering the main building drain from the public sewer.
Prohibited Traps: Codes often forbid bell traps, crown-vented traps, and traps relying on moving parts. 

Interceptors and Separators
These are specialized, often larger devices (sometimes multi-compartment tanks) installed in industrial or commercial settings to separate and capture contaminants before they enter the wastewater system. 

Grease Interceptors (Grease Traps): Mandatory for commercial kitchens to separate fats, oils, and grease (FOG) from water. They use cooling to solidify grease and baffles to retain it, protecting pipes from blockage.
Oil/Gravel Separators: Common in garages, car washes, and service stations to capture heavy solids (sand/gravel) and lighter oils.
Solids Interceptors: Specialized units designed to trap materials like plaster, jewelry, or heavy debris in commercial settings. 

Key Requirements
Location: Every plumbing fixture must be separately trapped, except for specialized cases like combined sinks.
Maintenance: Grease interceptors require regular, periodic pump-outs (often required when 25% full of solid waste or every 3 months).
Venting: Traps must be protected from siphonage and backpressure via a vent pipe.
Accessibility: All traps and interceptors must be accessible for cleaning and inspections.