Grease Traps, Fog Traps, Interceptors, Separators, Grease Abators, Grease Arrestors, Grease Removal devices, HGIS, GRUs… why is something so simple in concept, made out to be so complicated?
There is a lot of terminology for this device that in most cases is just a liquids storage tank with an inlet, outlet and a couple of baffles. First, outside of the US, there is no real distinction drawn between a grease separator, trap, interceptor or similar sounding name. Inside the US though terminology used can be important and mean different things to different people.
Generally, a Hydromechanical grease interceptor (HGI) is the term used by the Uniform Plumbing Code (UPC) to describe a grease management device that treats commercial wastewater from food establishments using gravity separation aided by a vented flow control. They are typically installed indoors and connected to one to four sinks in the kitchen and can be either above floor or below. In the device, grease separates from kitchen wastewater and rises to the surface where it is trapped behind a baffle wall. Only the cleaner, heavier water that falls to the bottom is allowed to pass under the outlet baffle and down the drain. The trapped grease is usually emptied by a pumping company before it reaches 25% of the tank’s capacity. In most cases this is likely to be once a month.
In the US anything designed to handle less than 100 GPM flow must be approved before sale under ASME A112.14.3 or PDIG101. Both standards are almost identical and require physical testing of a device by a recognised standards agency such as the NSF. There is no specific test for units claiming to handle higher flow rates though municipalities may specify a minimum volume such as 750 gallons.
Devices with flow rates below 100 GPM are generally above ground interceptors and usually fit under sinks or in a designated room near the kitchen whereas 750 gallon systems are more commonly outside in the ground.
In the Unform Plumbing Code reference is made to Automatic Grease Removal Devices (AGRDs). These are designed and tested in the same way as the HGIs. They have one major difference though and that is the inclusion of a grease removal mechanism or system that automatically extracts the trapped grease daily. This feature effectively eradicates the need for third party pumping companies to come in every month. This saves the customer in terms of pumping costs. Most AGRDs have baskets as well to filter the solid waste. The brand Grease Guardian uses a drum in their AGRDs to remove the surface grease. The standard ASME A112.14.4 tests the grease removal ability of the AGRUs additional extraction feature.
The Uniform Plumbing Code is referenced in many Municipal Fats, Oils and Greases (FOG) ordinances across America. Those that don’t, may have their own specific requirements in relation to the size and style of management device to be used. Always check what your local authority recommends.
The Grease Guardian HGI line is tested against ASME A112.14.3 and the Grease Guardian AGRU line is tested alos against A112.14.3 but also A112.14.4 and PDIG101.