Determine the flow rate of your sink:
  1. Calculate the capacity of the sink in cubic inches (measurements of one compartment), and multiply that total by the number of compartments:

    x x =

  2. Convert the capacity from Total cubic inches to gallons per minute (GPM):

    ÷ 231 =

  3. Adjust for displacement (displacement takes into consideration the actual useable capacity of your sink):

    x 0.75 = x 2 =
  4. * The resulting GPM is the required flow rate to drain the sink in one minute. You would then choose a grease trap with a GPM flow rate close to this number.

If Draining Multiple Sinks Into One Grease Trap

  1. Determine the flow rate for each sink to be serviced by the grease trap using the same calculations as a single sink.
  2. Add together 100% of the largest flow rate, 50% of the second largest, and 25% of all others.
  3. The result is the recommended flow rate (in GPM) of the grease trap.