What Size Grease Interceptor do You Need?
Determine the correct size for your kitchen.
Grease interceptors are sized according to the rate of incoming flow, in gallons per minute (GPM). To find which interceptor is right for your needs, use the formulas below to determine the flow rate for each sink. You can then use that number to select the interceptor that most closely fits your requirements. Be sure to also check your local codes for additional requirements.
1. Calculate the capacity of the sink in cubic inches:
________(Width) × ________(Depth) × ________(Height) = ________Cu. In.
2. Convert the capacity from cubic inches to gallons per minute (GPM):
________Cu. In. ÷ 231 = ________GPM
3. Adjust for displacement:
________GPM × 0.75 = ________GPM
4. Result is the flow rate required to drain the sink in one minute.*
*Note: If drain down time is not critical, an interceptor with a lesser flow rate - up to half the calculated flow rate - may be specified.
Sizing for Multiple Fixtures
1. Determine the flow rate for each fixture to be serviced by the interceptor.
2. Add together 100% of the largest flow rate, 50% of the second largest and 25% of the flow rate for all others.
3. Result is the recommended flow rate of the interceptor.
Note that associated with the incoming flow rate is an interceptor's capacity. The rated capactiy, in pounds, is listed as twice the flow rate, in GPM. For example, a 10 GPM interceptor has a rated capacity of 20 lbs.