Grease Trap Sizing Calculator
What size grease trap do I need?
The Grease Trap Sizing calculator accurately sizes passive grease traps, grease interceptors, and automated grease recovery devices (GRD) for restaurant kitchens & foodservice facilities.
Passive grease traps or interceptors are like Reservoirs
Passive Grease traps store and accumulate the fat, oil, grease, (FOG) and food solids until the grease trap is pumped out. Passive Grease Traps require time for the FOG to separate and settle from the wastewater (detention time). Automatic Dishwashers are not attached to a grease trap as the high volume wastewater outflow will bypass the grease trap. It is important to size a grease trap larger than calculated (round up to next available size only). A grease interceptor that is extremely oversized will have longer periods between pump-outs. The rotting grease will adversely affect the structure of the grease interceptor.
Grease Recovery Devices control Wastewater inflow
A Grease Recovery Device (Goslyn) separates the FOG from the wastewater as it enters the device. Goslyn controls the inflow of effluent or wastewater. Wastewater with a high flow rate (automatic dishwasher) will not bypass a Goslyn GRD. A 3-compartment sink will only have a longer drainage time period if the Grease Recovery Device is undersized.
Automatic dishwashers attach to Goslyn Grease Recovery Devices. Automatic dishwashers do not attach to passive Grease traps. The GPM of an automatic dishwasher is not included in Grease Recovery Device and Grease Trap sizing formulas.
2 or 3 Compartment sink Cubic Capacity = width x length x depth (in inches)
Volume in Gallons = Cubic Capacity / 231
1 US Gallon = 231 cubic inches (volume)
Remember: Hydro Mechanical Interceptors are Measured By FLOW (GPM)
GPM for an In-ground Grease Interceptor is multiplied by a factor of 30 (minutes) to accomodate settling of food solids and hardening of animal fats (retention time)
In-Ground Grease Interceptor (Gallons) = Calculated GPM X 30
(30 Minutes retention time as suggested by the Plumbing and Drainage Institute)
Remember: Gravity Interceptors are Measured By VOLUME (GALLONS)
Bigger is not Better - Accurate Sizing is Key
Stainless Steel Never Leaks, Splits or Rusts
The Grease Trap / Recovery Device calculations are based on the worst case scenario where the 3-compartment sinks are full of wastewater and all draining at the same time. This scenario must be taken into account but seldom occurs.
Wastewater flow rates of a 3-compartment sink is the most important aspect of a grease trap sizing formula
Drainage Load is a Key Sizing Variable for Passive Grease Traps or Grease Recovery Devices
40 LPM or
60 LPM or
80 LPM or
GPM = Gallons / Minute
LPM = Litres / Minute
Conventional or Passive Grease Trap Size required