The significance of Schier's ASME A112.14.3-2018 Type D Certification

This document is intended to outline the background behind the decision to invest in the research and development of units that meet the ASME A112.14.3 standard rating of Type D and how this certification rating changes the industry for the better.

What is ASME A112.14.3?

ASME A112.14.3 is an industry performance standard that provides both a certification flow rate as well as a maximum grease capacity and efficiency percentage at failure. The primary function of the standard is to lay out a codified method of testing grease interceptors. The tests use lard as a medium to ensure the unit functions properly in the field and measures storage volume as well as efficiency. ASME A112.14.13 is widely regarded as the go-to standard for testing hydromechanical interceptors (HGI); almost all US and Canadian manufacturers utilize this standard to test and certify their units.

All Schier interceptors in the Great Basin lineup are certified to ASME A112.14.3 and all of our test reports are publicly available for each product. For example: the GB-250 is certified to 1,895 lbs at 100GPM with an average efficiency of 96.7% at failure.

Ratings and Types Explained

The ASME standard sets ratings and types to better understand how to specify and use HGIs. Ratings of HGIs are divided into four types, A, B, C and D. Schier has historically tested all interceptor units to Type C which allowed the interceptors to be shipped with an integrated flow control that the plumber did not have to install separately from the unit. Schier was the first adopter of this technology.


Authorities Having Jurisdiction (AHJs) across the industry have been asking for units that do not require flow controls in order to eliminate the inherent clog problems that come from restricting the flow of waste water through an aperture to limit the flow - this is the Type D standard. Although flow controls are great for certifying and running lab tests, they can be a challenge in the field to install correctly and can lead to maintenance issues in the future if not properly maintained. They are useful in situations with high flow or high head pressure, so having an option for these is important. The best outcome for both the AHJ and the end user is a system that operates well in high pressure, high flow situations. AHJs have also been increasingly requiring indirect connections in kitchens to eliminate the possibility of a backup into any sink that is used for food prep. Any clog in an indirectly connected system will result in wastewater backing up onto the floor of a kitchen through a floor sink that can be easily cleaned up after the backup is addressed without contaminating any surfaces that might contact food being served to customers. 

Why is Type D better?

 Type D allows manufacturers to test an interceptor without any internal or external flow control. It also more closely replicates the majority of jurisdiction requirements for indirect connections in commercial kitchens. Type D is designed to test an interceptor in an indirectly connected system while Types A thru C require a direct connection. See below for a schematic of the Type D test rig setup from the standard.

Grease Interceptor Test Configuration for Rating Type D (Figure 3)


The floor sink and air gap are what sets the Type D apart from the Type C configuration. The ball valve in Figure 3 lets the testing lab set the flow rate for the system and opens the door for an interceptor to be certified to a specific rate with no flow control. This replicates how a kitchen worker regulates the flow to the floor sink to avoid overflow to the floor sink.

Note: Type C also allows for no flow control, but the system doesn’t allow for the lab to regulate the flow into the interceptor. Looking at Figure 2 below in contrast to Figure 3, note that the system is directly connected, so there is no floor sink or air gap. There is also no ball valve to regulate the flow into the system.

 Grease Interceptor Test Configuration for Rating Type C (Figure 2)



Referencing section 2.3.1, the system must be run wide open which means a specific flow rate cannot be achieved. It flows at whatever the system runs at (typically much higher than 100GPM), but the standard only recognizes the flow rates in table 1 below.



This information suggests that a Type C unit without flow control cannot be certified to a known flow rate under the current ASME standard. This oversight may be addressed in future updates to the standard.


By switching to Type D certifications, Schier is able to offer the first units certified to ASME A112.14.3 that do not require a flow control to be installed. This delivers value to the end user by eliminating aperture designs that can lead to clogs and maintenance issues. This also means that the installer won’t need to install a separate flow control outside of the unit or even mess with ensuring one is installed into the unit. AHJs are strongly in favor of this as it eliminates future maintenance issues (clogs, system backups, etc) and also shows that Schier units are designed specifically with indirectly connected systems in mind while still maintaining peak performance in directly connected installations.

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