How you calculate the correct size of Grease Trap?
Full Customer Question:
How do you calculate the correct size of grease trap for a restaurant, hotel, canteen, pub or cafe?
Answer:
There a number of ways to size and select a grease trap according to EN1825-2:2002 Grease Separators – Part 2: Selection of nominal size, installation, operation and maintenance:
1. Measurement of flow
2. Based on catering equipment
3. Based on type of establishment
4. Special Calculation
All of the methods are complex and time consuming. The good news is that we can do it for you for free! However, in this post we will show you and example of how to do it based on Establishment Type.
The formula is:
This is where is gets complicated!
The Temperature Factor, Density Factor and Detergent and Rinsing Aid are read off tables/graphs:
The Max Wastewater Flow (l/s) Qs requires another calculation!
To this calculation you first need to work out the average flow volume per day from the establishment from the formula and tables below:
So tying it all together and taking the option of a Canteen Kitchen here is a full sample calculation:
1200 Meals/day from 07:00-15:00 (8 hours/day)
t = 8 h
M = 1200 meals
Vm = 5 l (from table)
F = 20 (from table)
V = 1200/day (M) x 5 l (Vm) = 6000 l/day.
QS = 6000 l/day (V) x 20 (F) ÷ 3600 x 8 h (t) = 2.33 l/s
ft = 1.0 fd = 1.0 fr = 1.3
2.33 l/s QS x 1.0 (ft) x 1.0 (fd) x 1.3 (fr) = 3.03 l/s
Nearest separator: NS 4.0 l/s (BMS GT04)
The whole process is quite complicated! Let us do the hard work for you, give us a call on +353 43 3326100 email us or email us on info@butlerms.com
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