A grease trap is an interceptor whose rated flow is 50gpm or less and is a device located inside a facility and/or under a sink designed to collect, contain, or remove food wastes and grease from the wastewater while allowing the balance of the liquid waste to discharge to the wastewater collection system by gravity.

Grease traps are typically found in commercial locations that cook large amounts of food, such as restaurants, hospitals, schools and institutions. 

B.  An approved flow control or restricting device is installed to restrict the flow to the grease trap to the rated capacity of the trap.

C.  An air intake valve allows air into the open space of the grease trap to prevent siphonage and back-pressure.

D.  The baffles help to retain grease toward the upstream end of the grease trap since grease floats and will generally not go under the baffles.  This helps to prevent grease from leaving the grease trap and moving further downstream where it can cause blockage problems.

E.  Solids in the wastewater that do not float will be deposited on the bottom of the grease trap and will need to be removed during routine grease trap cleaning.

F.  Oil and grease floats on the water surface and accumulates behind the baffles.  The oil and grease will be removed during routine grease trap cleaning.  

G.  Air relief is provided to maintain proper air circulation within the grease trap.  

H.  Some grease traps have a sample point at the outlet end of the trap to sample the quality of the grease trap effluent.

I.  A cleanout is provided at the outlet or just downstream of the outlet to provide access into the pipe to remove any blockages.

J.  The water exits the grease trap through the outlet pipe and continues on to the grease interceptor or to the sanitary sewer system.

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