May 31, 2023
Hydromechanical grease interceptors (HGI) traditionally utilize flow control devices to manage incoming flow rates according to certification standards. To grasp their usage and evolution, we must journey back to the inception of flow control regulations in the Uniform Plumbing Code (UPC), dating back to World War II.
In 1948, the UPC introduced a requirement for grease traps or interceptors, necessitating an approved flow control or restricting device for each fixture connected to them. The key stipulation was that these devices must collectively not exceed the interceptor's rated capacity, and they must not have adjustable or removable parts. However, the application's specifics were not entirely clear.
By 1952, the UPC refined these requirements to clarify that flow control devices were intended for fixtures or equipment connected to the grease interceptor. This clarification remained in place until 1997 when an exception introduced ambiguity.
Starting with the 1997 UPC, a new format was adopted, and fixture/flow control requirements were placed in section 1014.3. An exception was added, permitting "Listed grease traps with approved type flow controls or restricting devices" to be installed as per the manufacturer's instructions. This exception contradicted previous requirements that clearly stated flow control devices must be placed in fixture tailpieces or drain outlets.
The 2000 UPC brought substantial changes to section 1014.3, introducing the requirement for vented flow controls for each fixture. The code no longer demanded these devices to be in fixture tailpieces or drain outlets. Instead, it necessitated a vent for both the fixture or equipment and the flow control. The exception deferred the installation specifics to the manufacturer's instructions.
In 2006, the UPC introduced the term 'Hydromechanical Grease Interceptor' and defined it, encompassing flow control Types A, B, C, and D. The requirements for vented flow control devices remained similar to the 2000 edition, creating ambiguity about their installation location.
The 2009 UPC aimed to resolve these issues by specifying that fixtures or equipment connected to Type A and B hydromechanical grease interceptors must discharge through a vented flow control. The location and functionality of these devices were better defined, but some distinctions still needed clarification.
In 2019, Schier introduced the first Type D certified hydromechanical grease interceptor (GB-500-B) that doesn't require a flow control device, harking back to the original valve-based flow control testing.
Flow control continues to evolve and we are seeing advances in technology for better, more efficient units. Ultimately, flow control is starting to take a secondary role when interceptors are sized. Sizing interceptors for grease capacity continues to grow and is becoming ubiquitous in the industry.
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