All too often not enough consideration is given to the required capacity and flow rate that the drainage needs to handle now, and may potentially need to handle in the future. Insufficient drainage capacity leads to flooding which compromises health and safety in the workplace and increases the risk of cross-contamination. It’s important to ensure the layout of the drainage matches the layout of the production equipment.
What is a flow rate?
Flow rate is the amount of liquid that comes through drainage in a given time.
The default method for measuring flow rates is by EN norm.
EN1253-1 = European methodology for determining the nominal flow rate for commercial inlets. This European Standard classifies floor gullies, gives guidance for places of installation and specifies requirements for the construction, design, performance and marking of factory made gullies for use in drainage systems requiring a trap with a depth of water seal of at least 50 mm.
For the specific needs of food and beverage industry, this method is not optimal as machinery outlets are often positioned directly above the drain to make the water flow directly into the gully body. This is because drainage here is not designed to act as an outlet for water on the floor, but as an extension of the wastewater outlet which is discharged directly from machinery. It is also necessary not to spill any water on the surrounding floor.
ACO has developed a methodology to measure ACO gully flow rate. It resembles the following drainage layout and is crucial for determining the right product solution for use in beverage production and other food and beverage sites. Selecting the right product according to its flow rate can now be carried out more accurately, especially when drainage is used to take in large amount of water at once.
Direct = Is a method to determine drainage flow rate capacity with a foul air trap, when the source of water is positioned directly above the drain. In order to select to correct ACO gully, you need to know the maximum amount of water which will be discharged from machinery, for example 6,000l / 5 minutes = 6,000/300 = 20 (l / s)
Why do we use both methods?
It depends on how the drain is used - if for some reason it is not possible to place the process water outlets from the technology directly above the drain, then it is necessary to use only lower values identified by the using EN1253-1 process.
Why does the Food & Beverage industry require the use of drains in accordance with the direct methodology?
Even wet floors in food and beverage production will cause a significant health and safety risk. Standing water on a floor can also interrupt production. A good drainage design does not use the floor to lead or retain water discharged from machinery. All waste water should be directed straight into drains without spilling on the floor.
Requirements for measuring flow rate according to the ACO direct methodology:
- Air gap - The drain must be exactly below and in the middle of the waste water outlet on machinery - the pipe is ideally one to two times DN above the floor.
- Unless mesh gratings are specified, gratings can cause water splashing and therefore negatively affect the performance of the drain.
- A pipe system with sufficient performance.