Thursday, March 5, 2015

YouTube Video - Grease Production Sizing Method

I realize that I recently blogged about the topic of Schier's Grease Production Sizing Method (here), but as I travel around the country visiting with pretreatment professionals I repeatedly see the need for a better sizing approach for grease interceptors. created a video to provide another tool to help jurisdictions, specifiers and contractors to not only understand how to size by grease production but also to be able to quickly explain the method to anyone else.

Flow rate or liquid volume based sizing for grease interceptors is inaccurate and inadequate, having led to thousands and thousands of incorrect installations across North America.

Grease Production Sizing is the only method that considers how much grease a restaurant will produce to ensure that the grease interceptor selected has enough capacity for a consistent and affordable pumpout schedule.

Here is a link to the video if you want to check it out:


  1. This sizing methodology is very nice if we lived in a static world, which we do not. Menus change, ownership changes, seasonal populations change (meals served per day), why even the clocks change this weekend. Think about this: Even the help changes! Some properly scrape and wipe pots and pans and serving ware of grease, others blow it down the drain. A grease interceptor sized using this method is assuming the Food Service Establishment and the "trained help" will be the same today as it is tomorrow. This is highly unlikely. What I also find peculiar about this posting is that the pump out time is calculated when the interceptor is at capacity with goal to establish a "consistent and affordable pump out schedule". If that isn't rolling the dice, I don't know what is. I don't know of one pretreatment professional that would consider that to fall under best management practices. The pump out schedule should always be determined by the local jurisdiction. Basically, I find this posting to be irresponsible at best, as it has nothing to do with the real dynamic world we all live in.

    1. I agree 100%! No one can determine nor foresee how staff will conduct themselves in the kitchen. That is absurd! I've been inspecting grease interceptors and traps for almost 7 years now and I have become pretty good at determining a schedule without factoring in the inconsistencies in a FSE (Food Service Establishment). I do this by calculating percentages with a dipstick. As far as affordability; that is certainly NOT a consideration of mine in any way. It should not be considered; it reeks too much of favoritism.

  2. There are many factors to consider in keeping your grease interceptor efficient is the point. I don't think this post is irresponsible at all. And I don't think you can rely on the AHJ to determine all situations and scenarios either.

  3. Sorry to have to post as anonymous 2. My opinion is that sizing methods just get you in the ballpark of reasonableness of cleaning intervals. For gravity grease interceptors, a bigger one just makes that interval longer.

  4. I appreciate the comments and engagement on this topic. Good points about how restaurants change over time, which is why inspections and monitoring are critical to any successful FOG management program. The advantage of the GPSM is that it allows for establishing a pump out schedule up front, whereas flow rate or liquid volume sizing does not. Inspections and monitoring by pretreatment should result in modifications to the pump out frequency to ensure compliance with discharge limits. With respect to gravity interceptors, bigger isn't necessarily better. Capacity should be looked at in conjunction with efficiency, but there is no performance test required for gravity interceptors that could provide a scientific basis for their use. Studies are ongoing in an effort to prove that a residential septic tank is a viable commercial gravity grease interceptor, a dubious proposition that several recent studies have called into question.