Commercial Kitchen Plumbing Engineering
A commercial kitchen sends water from prep sinks, pot sinks, and dishwashers through one drain line. The interceptor on that line has to be large enough for those fixtures, and the inlet, baffles, and outlet have to stay clear.
When the outlet clogs, grease passes downstream. Cleaning includes the box itself and a check of the pipes on both sides. Local plumbing rules decide the size. This page is the service explanation, not an engineering stamp.
Grease.org looks at the interceptor on the kitchen line and at the inlet and outlet pipes. Sizing that line, and stamping a drawing, is a plumber's job and a local code question. This page explains why a clogged outlet lets grease pass. It is not an engineering stamp.
Why the pipes on either side matter
An interceptor only works if the kitchen line is plumbed so greasy water actually enters it, slows down, and leaves from a point below the floating cap. The inlet should drop into the box without jetting across the surface. The outlet should draw from the clearer water, behind a baffle or a tee. A missing tee, a tee that has rotted, or an outlet that sits in the grease layer will pass fat no matter how often the box is pumped. That is a plumbing defect. Pumping makes it visible. A plumber fixes it.
Upstream mistakes are just as common. A food grinder on the grease line fills the box with solids and is banned by many codes. A dishwasher tied in without the manufacturer's approval brings detergent that emulsifies fat and carries it through. A long unvented run can siphon the trap or leave it air-locked. Floor sinks that take mop water and fryer dumps become the real inlet, and they bypass a beautifully sized tank in the parking lot. The designer has to walk the kitchen, not only the drawing.
Stamped drawings and the interceptor rating belong with the plumber and the engineer of record. The company pumps, cleans, and repairs traps and the immediate inlet and outlet problems a cleaning visit uncovers. Repair in that sense is a broken baffle, a damaged lid, or a line that has to be opened because the trap can no longer be cleaned. A resize or a new fixture layout is a plumbing project with a permit.
When you book a cleaning, say what is upstream. A new dish machine or a new grinder since the last visit explains a trap that failed early. The cleaning crew can confirm a buried outlet. They should not be asked to bless a layout that needs an engineer. Clear pipes, a legal fixture list, and a pumped box are three different completed jobs. A kitchen that has all three passes the inspection that a kitchen with only one of them fails.