Grease trap is used to take care of the fat that is flushed down the drain before operating it gets out into the public grid. The reason for doing this is that the fat can clog the pipe network and create clots.
The demands on the need varies between municipalities, but in general, the requirement is that there should be a grease trap on virtually all commercial kitchens serving hot food. The toilets and the like should never be connected to a grease trap.
At higher temperatures of sewage effectively reduces ethylene on grease trap this fact is compensated with temperature factor according to table below.
|Temperature of the wastewater at the inlet
|<= 60˚C ||1,0|
|> 60˚C ||1,3|
Density factor is the factor that handle the density of the fat that is flushed down the drain. If the density is unknown, factor set to 1.0. On the other hand the density known, the graph below used to obtain the correct factor.
Exceeds the density of fat is 0.94 g / cm 3 is the factor to 1.5.
Nedan visas densiteten på ett antal vanligt förekommande fetter.
||Density at 20˚C in g/cm3
|Animal grease||0,85 - 0,94|
|Butter grease ||0,91|
|Coconut butter ||0,89 - 0,94|
|Castor oil ||0,95 - 0,97|
|Coconut oil ||0,92 - 0,93|
|Corn oil ||0,92|
|Fish oil ||0,89 - 0,94|
|Linseed oil ||0,93 - 0,94|
|Olive oil ||0,91|
|Palm oil ||0,91 - 0,92|
|Rapeseed oil ||0,91 - 0,92|
|Sesame oil ||0,92|
|Vegetable oil ||0,95 - 0,97|
Cleaning factor takes into account how much detergent and fabric softener used in washing. The type of detergent and fabric softener
should be used sparingly and should be chosen so the separating effect on the fat reduces the effectiveness of the grease trap.
|Use of detergent and rinse aid
|Never used ||1,0|
|Rarely used ||1,3|
|Special case ie hospital ||1,5|
Nominal size is the calculated value used to select an appropriate size of a grease trap.
Sludge separation Volume
It contemplates the size of the chamber of the grease trap handling the sludge that comes with the wastewater.
Mean wastewater volume
Refers to the average value of the waste water that reaches the grease trap per day in liters.
The maximum flow rate
is the main flow from the actual plant that reaches the grease trap.
Are there two or more drain lines that are not connected to any device, these must also be added to the calculations.
Refers to how many hours per day that the plant is running at average.
Peak flow coefficient
This is a factor which depends on the type of activities carried out in the actual plant.
Refers to the number of meals served per day plant.