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The Australian Standard for grease trap

grease separators for kitchensCollections of Fats, Oils, and Grease (FOG) within a drainage system are a serious problem if not dealt with, especially where large commercial amounts may be passing through the drain system every day. Without the right equipment, the drainage system may be impacted, affecting the water quality, efficiency of the drainage infrastructure from within the building through to the sewer plants.

ACO offers a range of grease traps that provide hygienic and effective methods of dealing with these substances.

So that we can select the correct grease trap, ACO proposes a three-stage decision selection process:

Stage 1 – Consider wastewater contents
Stage 2 – Establish trap size
Stage 3 – Select trap type (ground installation or free standing installation)

grease separator standardsACO’s grease traps are made to the specifications of the European Standard EN 1825: Grease Traps. ACO believes this to be the most suitable and relevant recognized performance based standard internationally.

Discussion has existed for a number of years on the suitability of Australian Standard, AS 4494: Discharge of commercial and industrial liquid waste to sewer regulation. Some highlight the European Standard EN 1825’s is more relevant as it is reflective of the concerns of all of the industry’s stakeholders. It is therefore more widely accepted, globally, than any other standard.

grease trap specificaitonTo add substance to the topic, we explore the case behind this argument that compares the similarities and differences between these 2 standards and their influence.

Australian Standard, AS 4494: Discharge of commercial and industrial liquid waste to sewer, states that the receiving water authority has the power to regulate the use and design of grease traps in their jurisdiction.

Local water authorities have specific regional requirements that guide the specifier to selecting the size of the grease trap, the total volume of wastewater to be held in retention and other criteria relating to the approval of its installation.

To ensure the longevity of the installation, water authorities usually provide a conservative estimate for the volume of wastewater to be treated.

Nationally, this creates inconsistencies with grease trap sizing across all Authorities and their regions.

Some water authorities even require additional design requirements; for example, extra height above the grease trap maintenance opening or the inclusion of baffle caps. Whilst these rules hold strong, often the reasons for them are either forgotten or out of date.

The International Standard, EN 1825: Grease Traps specifies a nominal size (NS), a repeatable sizing method, provides performance based criteria for product design and quality control. It is as much a manufacturer’s standard as it is a guide for specifiers. The two ends of the design spectrum are linked.

EN 1825 specifies a wastewater quality requirement of a maximum 25mg/L concentration of hydrocarbons. This ensures that a grease trap can effectively separate Fats, Oils and Grease (FOG) from wastewater, before discharging it into the sewer system. EN 1825 has

separation of fatsLongevity is also a very important factor for ACO products to ensure our clients get the most from their grease traps. That is why our products are designed to withstand 25 years of use above ground, and 50 years of use below ground. This is in line with German Standard DIN 4040-100 and ISO 19001.

Because of these specifications, ACO Australia believes that the EN 1825 is the most appropriate internationally recognized performance based standard for its grease traps. This is why ACO designs and manufactures its vast range of grease traps in accordance with EN 1825.

grease trap separator calculatorEN 1825 uses three alternative methods to calculate the required size for a grease trap based on:

  1. Number of meals per day – helps estimate the volume of water to be treated.
  2. Hydraulic load – maximum flow rate discharged from kitchen equipment.
  3. Meat processing units – number of animals that might be processed per week.

Following these methods, you will be able to calculate the (NS). The (NS) stands for Nominal Size and is an approximate maximum flow rate in litres per second specified to enter the grease trap. ACO’s product tables specify the NS for each of its grease traps.

ACO has an online sizing calculator according to EN 1825, which you can try out online at:


ACO support services

ACO’s Technical Services department offers obligation free advice to ensure the correct product is chosen. Extensive research and development, both independently and in conjunction with leading academic institutions and research bodies, is the cornerstone of ACO’s success.

Revit and DWG file extension formats are available to assist planning, specification and installation.

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