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Stone Industries can
install your new or replacement grease trap or repair your existing
grease trap in no time at all.
For a free estimate call our Project Manager, Dean Burdick, direct at (518)
232-6707 or click
here
to email him, or call the office at (800) 446-6331.
Need your existing
grease trap system jetted to keep it draining smoothly? We do that
too! Check out our
jetting services or call for a quote
today!
What is a Grease Trap?
Grease traps are passive devices required by
local municipalities to stop grease, fat, oil,
wax or debris from entering the city's sanitary sewer system. Such materials cause
blockages in the system, which cause backups and overflows. They are designed to
separate grease from
wastewater so that it can be removed before it enters the sewer
system. All restaurants, caterers, school cafeterias and other commercial cooking
facilities must,
by law, avoid discharging grease into the municipal sewer system.
In
order to function properly grease traps must be pumped and cleaned on
a regularly
scheduled basis. Check out more on our
Commercial Grease Trap Service page, or call
the office at
(800) 446-6331 or click
here to email your questions.
Grease Trap Sizing Calculations
Please note that the following information is provided as a guide only, and is not to be used as a
substitute for a professional evaluation of any business. Grease traps must be located at least 10
feet from hot water faucets. All hot water must cool to 120° F before entering the grease trap. The
size of the grease trap must comply with the Uniform Plumbing Code. Any sink or disposal that
can carry grease must empty into the trap.
Sizing should always be left to a trained professional. This section is intended as a guide to
familiarize the reader with some basic sizing rules. Requirements are determined by the volume of
waste water that the interceptor can handle compared to demand. Unit selection depends on the
type desired and its capacity rating in gpm. The Plumbing and Drainage Institute (PDI) defines
standard sizes that are roughly equivalent to gpm of flow.
The National Plumbing Code lists drainage fixture-unit values of various plumbing fixtures based
on drain outlet or trap size. These values are converted to gpm discharge rates assuming 7.5 gpm
discharge to represent one fixture-unit. This information is illustrated below.
The discharge rate will help to determine the model needed.
| Sizing Chart |
|---|
Trap / Outlet Size
|
Fixture-Unit Value |
GPM Equivalent |
| |
1 ¼"
1 ½"
2"
2 ½"
3"
5"
|
|
1
2
3
4
5
6
|
|
7.5
15.0
22.5
30.0
37.5
45.0
|
|
To determine the size unit required, take the GPM
equivalent for all the drains in the system and
add them up. This will
give you the required GPM for the entire system. For example, take a
double sink with two 2" drains. The sizing chart indicates that each of these drains will produce
22.5 gpm discharge, making the total requirement 45 gpm.
Alternate Method
- Calculate volume fixture in cubic inches
- Convert this volume to gallons
- Multiply by .75
- Calculate flow rate and drainage period (1 or 2 minutes)
The flow rate determines the grease trap model required.
For Sinks:
| |
Sink Size
Interior Measurements |
# Bowls |
Capacity
in Gallons |
PDI SIZE
(1 min.) |
PDI SIZE
(2 min.) |
|
|
12" x 18" x 6"
14" x 16" x 8"
18" x 20" x 8"
16" x 18" x 8"
18" x 20" x 8"
20" x 30" x 8"
20" x 24" x 12"
20" x 22" x 8"
20" x 22" x 12"
24" x 24" x 12"
|
1
1
1
2
2
1
1
2
2
2
|
4.2
5.8
9.4
15.0
18.7
15.5
18.7
23.0
34.0
44.9
|
7
7
10
15
20
20
20
25
35
50
|
4
4
7
10
10
10
10
15
20
25
|
|
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* PDI = Plumbing and Drainage Institute standard size equivalent to gpm of flow
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