Brochure

- 10 -
Sizing by Flow Rate
Table A - Procedure for Sizing Grease Interceptors
STEP FORMULA EXAMPLE
1 Determine cubic content of xture by multiplying length x
width x depth
A sink 24” long by 20” wide by 12” deep.
Cubic content: 24 x 20 x 12 = 5,760 cu in
(61.0 x 50.8 x 30.48 cm
3
)
2 Determine capacity in gallons.
1 gallon = 231 cu in
Contents in gallons:
5,760 / 231 = 24.9 gallons
(94,451.42 / 1,000 = 94.45 litres)
3 Determine actual drainage load.
The xture is normally lled to approximately 75% of capacity
with water as the items being washed displace about 25% of
the total xture content.
Actual drainage load = 75% of xture capacity
Actual drainage load:
.75 x 24.9 = 18.7 gallons
(0.75 x 94.45 = 70.84 litres)
4
Determine ow rate and drainage period.
In general, good practice dictates a one minute drainage pe-
riod; however, where conditions permit, a two minute drainage
period is acceptable. Drainage period is dened as the actual
time required to completely drain the xture.
Flow rate = Actual Drainage Load
Drainage Period
Calculate ow rate for one minute drainage period:
18.7 / 1 = 18.7 g.p.m. ow rate
(70.84 / 1 min. = 70.84 l.p.m.)
Calculate ow rate for two minute drainage period:
18.7 / 2 = 9.4 g.p.m. ow rate
(70.84 / 2 min. = 35.42 l.p.m.)
5 Select Interceptor.
From Table B select the interceptor with a ow rating at least
equal to the calculated ow rate. When the calculated ow rate
falls between two sizes, select the larger of the two
interceptors.
For a one minute drainage period:
18.7 g.p.m. (70.84 l.p.m.) ow rate = 20 g.p.m. G.I.
For a two minute drainage period:
9.4 g.p.m. (35.42 l.p.m.) ow rate = 10 g.p.m. G.I.
Table B -Metric conversions based on PDI sizes
PDI Size 4 7 10 15 20 25 35 50 75 100
Flow Rate US Gallons per Minute (gpm) 4 7 10 15 20 25 35 50 75 100
Flow Rate Liters per Second (L/Sec) .25 .44 .63 .95 1.26 1.58 2.20 3.16 4.74 6.3
Grease Capacity Min. (lb) 8 14 20 30 40 50 70 100 150 200
Grease Capacity Min. (kg) 3.63 6.35 9.07 13.61 18.14 22.68 31.75 45.36 68 91
Canplas recommends sizing by ow rate for Endura models. The use of a ow control with a Hydromechanical Grease Interceptor is
considered mandatory. Without a properly sized ow control, the discharge rate through into the interceptor may exceed the design rating of
the unit, causing lower eciencies and increase the risk of grease, passing into the downstream system. Be careful not to confuse liquid capacity
and ow rate. Liquid capacity is stated in gallons (or liters) while ow rate is referenced in gallons per minute (GPM) or liters per second (L/Sec).
Key Design Considerations
Fixture Capacity: Most commonly used and recommended method for Hydromechanical Grease Interceptors. This
method looks at the maximum capacity of xtures connected to the interceptor and the time taken to discharge that volume of
wastewater through the interceptor. Units are expressed in Gallons Per Minute (gpm).
Calculation takes 75% of maximum capacity of all xtures and based on a 1 or 2 minute period of time taken to discharge, results
in a gallons per minute ow rate. This number is rounded up to the next available size of interceptor, i.e. 16.7gpm become a
20gpm Grease Interceptor.
Pipe Size:
Pipe
Diameter
Maximum
Flow Rate
(gpm)
Size of interceptor
1-minute drain
period (gpm)
Size of interceptor
2-minute drain period
(gpm)
2-inch 20 20 10
3-inch 60 75 35
4-inch 125 150 75
Visit our website for our easy to use
online GI Sizing Calculator.
www.EnduraGICalculator.com