The Interceptor Whisperer’s Grease Interceptor Primer


Ken Loucks, aka the Interceptor Whisperer, looks at the history of grease interceptors, reviews the plumbing code and standards that govern them, and discusses how to appropriately size and select commercial grease interceptors.

Key Takeaways:

  • Usually teaches a 6 hour live training course
  • This talk is a primer of what he usually teaches at the FOG training institute
  • History of grease interceptors:
    • Pre WW2 there were a number of manufacturers and no universal rating system. When the US joined WW2 – FOG was rationed, sparking a fat salvaging campaign – the military looked at grease traps for army kitchens to capture FOG. No uniformity – asked for the first testing and rating protocol for GIs at IIHR lab. 
    • Clean Water Act in the 1970s shifted the industry
    • By the 1980s, the EPA handbook developed a diagram of a grease trap with sizing methodology – reinvented septic tank as a commercial trap – adopted in ordinance across the US!
    • Sizing and standards were revised when they realised that the EPA’s promoted sizing methodology was made up
    • 2006-2009: the industry wanted bigger tanks with more capacity that worked well – birth of high-capacity hydromechanical grease interceptors
  • All grease traps use gravity differential separation – all work similarly
    • There are other factors eg. velocity, turbulence, temperature, flow pattern that affect it. Flow pattern is the most important
  • GGIs vs HGIs
    • HGIs required a vented external flow control
    • Feels that GGIs are great septic tanks, but are terrible grease interceptors and he doesn’t advocate for them
  • Sizing and selection of GCDs
    • Challenges with model plumbing code sizing – focuses on flow rate which suggests that’s the only important factor
    • Categorising FSEs by grease production gives you a Grease Factor, which when multiplied with Meals/Customers per day and Days between pump outs = Grease Capacity Required
    • Advocates for all fixtures to be connected to a GCD. Specifically dislikes approving food waste disposal units (macerators).