CSLB C-36 Plumbing ContractorPlanning and EstimatingMedium
A plumbing contractor is reviewing blueprints for a new commercial kitchen. The plans indicate a grease interceptor must be installed and sized according to the Uniform Plumbing Code (UPC). Which of the following factors is MOST critical in determining the required size of the grease interceptor?
- AThe total number of plumbing fixtures in the entire building.
- BThe distance from the kitchen to the public sewer connection.
- CThe flow rate and type of fixtures discharging grease-laden waste.
- DThe anticipated occupancy load of the commercial kitchen staff.
Show answer & explanationAnswer & explanation
Correct answer: C. The flow rate and type of fixtures discharging grease-laden waste.
According to the UPC, the sizing of a grease interceptor is primarily based on the estimated flow rate of grease-laden wastewater from fixtures like sinks, dishwashers, and floor drains in the commercial kitchen. The type of establishment and its specific fixtures dictate the potential for grease accumulation.
Why the other options are wrong
- A. While total fixtures contribute to overall building wastewater, only those producing grease are relevant for interceptor sizing.
- B. Distance to the sewer connection is relevant for pipe sizing and slope, but not for the interceptor's capacity.
- D. Staff occupancy might indirectly influence fixture usage, but the direct input for sizing is the fixture's flow and waste type, not just the number of staff.
Grease Interceptor Sizing (UPC)
Grease interceptor sizing under the UPC is determined by the hydraulic load and grease retention capacity required for fixtures discharging grease-laden waste.
- Focuses on fixtures producing fats, oils, and grease (FOG).
- Calculations often involve drainage fixture units (DFU) for specific kitchen equipment.
- Retention capacity (in pounds) and flow rate (GPM) are key metrics.
Memory trick: Grease interceptors are like FOG filters, sized for the amount of oily water they catch.