# grease trap sizing requirements



## BSSTG (Aug 1, 2013)

Greetings all,

In a preconstruction meeting yesterday the subject of grease trap sizing came up. I had the architect add a note on the dwgs for the trap to be sized per IPC 1003.3.4. What I had not noticed previously with the adoption of the 2009 IPC that there was an added exception to these requirements (dummy me). Oh well, onward. The exception indicates to me that traps larger than 500 gallons and outside are not required to meet this section. I'm assuming that to apply to sizing per PDI G101 as well.

The Code reads thusly.

1003.3.4 Grease interceptors and automatic grease removal devices. Grease interceptors and automatic grease removal devices shall be sized in accordance with PDI G101, ASME A112.14.3 Appendix A, or ASME A112.14.4. Grease interceptors and automatic grease removal devices shall be designed and tested in accordance with PDI G101, ASME A112.14.3 or ASME A112.14.4. Grease interceptors and automatic grease removal devices shall be installed in accordance with the manufacturer's instructions.

Exception: Interceptors that have a volume of not less than 500 gallons (1893 L) and that are located outdoors shall not be required to meet the requirements of this section.

The section then goes on for more detailed requirements.

So, how do we size the grease trap if over 500 gallons and outside?

BSSTG


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## Gregg Harris (Aug 1, 2013)

BSSTG said:
			
		

> Greetings all,In a preconstruction meeting yesterday the subject of grease trap sizing came up. I had the architect add a note on the dwgs for the trap to be sized per IPC 1003.3.4. What I had not noticed previously with the adoption of the 2009 IPC that there was an added exception to these requirements (dummy me). Oh well, onward. The exception indicates to me that traps larger than 500 gallons and outside are not required to meet this section. I'm assuming that to apply to sizing per PDI G101 as well.
> 
> The Code reads thusly.
> 
> ...


  Several formulas are available based on the seating capacity, hours of operation, kitchen  equipment and type of dishes used in the establishment = pounds of grease retention required


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## north star (Aug 1, 2013)

*& = = = &*

BSSTG,

Take the number of plbg. fixtures that will be installed in your

cooking area application, apply all of the dimensions of each

fixture [ EX: a 3 comp. sink will have 3 dimensions; width, depth

& length ]........These calculations will provide you with a total

cubic amount of all fixtures.......Divide this Total Cubic Amount

by 231 to give you the gallons per minute [ GPM ] flow rate.

Take your Total GPM's and multiply that by somewhere

between 24 - 30 minutes, if you want to use a Grease

Interceptor that acts like a septic tank [ i.e. - an amount of

time for the gray water to separate from the F.O.G.

products ].......This total amount will provide you with the

[ min. ] size of interceptor that you need......If you desire to

have a faster acting interceptor, ...say around 5 mins. of

retention time, there are Grease Interceptor models out

on the market that accomplish this.......See both of the

links for performing sizing calculations.

One manufacturer' web site:

*Grease Interceptor Sizing Calculator | Grease Trap Sizing Calculator Guide*



One AHJ' web site:

*http://www.salisburync.gov/Departments/Salisbury-RowanUtilities/FOG/Documents/Grease%20Interceptor-Trap%20Design%20and%20Sizing/Grease%20Interceptor%20Detail%20and%20Sizing%20Worksheets/GI%20Sizing%20Criteria.pdf*



At one time in the near past, ...the PDI had a sizing calculator

link on its web site.



Hope this helps !

Also, don't forget to include the Floor Drains & the Service

Sink in the sizing calculations.

*& = = = &*


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## RJJ (Aug 1, 2013)

The Plumbing codes don't really cut it for proper sizing of grease traps. If you forget the 3 T's of grease then grease will flow out of the trap into the sewer lines and to the plant.


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## BSSTG (Aug 1, 2013)

Greetings,

I've said for years that the longer I live, the more I learn about bull crap that I never wanted to know anything about. I have to say that anything to do with grease traps fits into that category.

thanksabunch

BSSTG


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## RJJ (Aug 5, 2013)

Well I can agree in part to Crap! However, from the plumbing codes you will end up with a trap that is undersized. In the AHJ's we have use various formals to size traps for exterior use. Now after inspected and installing traps for over 25 years the is never a perfect fit.

For restaurant use with seating from o to a hundred a 1500 three compartment tank would be needed. Over 100 to 300 twin tank 2000 gals with separation in each tank is mandatory. We still have problems with this type of sizing even though it may seem a bit over the top.


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## mark handler (Aug 5, 2013)

The UPC does have sizing in the code

http://www.co.maui.hi.us/documents/11/28/Grease%20Interceptor%20Appendix%20H%20Form.PDF


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## peach (Aug 6, 2013)

Buy the referenced standards.. suck as it does, that's the only way you know if you comply.  Plan reviewer should have done it already.


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