Skip to main content
  • News Story

Expanded Clean Agent Extinguishing Systems Recognized Component Coverage

Now with the added benefit of identification by UL’s UR, C-UR and C-UR-US Marks.

extinguishing systems

June 17, 2019

Installation and use codes for clean agent extinguishing system units often cover a wide range of features and requirements for individual components, component compatibility and system unit assemblies. Testing standards can vary widely covering specific devices, materials and applications, or leaving the details to the designers and the authorities having jurisdiction. The lack of specificity can leave original equipment manufacturers (OEMs) scrambling to put the pieces together in one cohesive package.

UL Listed clean agent extinguishing system units have been used to provide specificity by covering the complete system unit and associated components under our product certification services. 

The extinguishing system units receive a UL Listed Mark, and the associated components, installation applications and use restrictions are all covered under the scope of the system unit manufacturer’s installation, operation, and maintenance instruction manual published as part of the certification information.

Certain components of the extinguishing system units are eligible for UL’s Recognized Component Mark. This is generally limited to components manufactured by specialty companies or that had limited risk of incompatibility, such as pressure gauges, electrical actuators and labels. Other components are marked with the manufacturer’s name and part number for correlation with the system manufacturer’s manual. Although this is a useful and idealized approach, other methods are also useful for identification of components and may provide valuable benefits to all stakeholders without impacting the integrity of the UL Listed Mark for the extinguishing system unit.

In fact, one misconception that has arisen in recent years with international authorities is that only the system unit is considered Listed and the components are not covered since they do not have a UL Listed Mark. This misconception may arise from the fact that other third-party certification organizations provide component-based approval and marking with little or no consideration for the complete systems. This can give the appearance of a “missing mark” when doing a visual examination of components for UL Listed system units, which is not actually the case. Thankfully, UL’s Recognized Component Program has a long history that works as a good solution when appropriately understood.

We are pleased to provide expanded UL Recognized Component coverage on a wide range of clean agent extinguishing system components with the added benefit of identification by UL’s UR, C-UR and C-UR-US Marks. Components that bear the UL Recognized Component Mark are incomplete in certain constructional features or restricted in performance capabilities and are intended for use as components of complete equipment submitted for investigation rather than for direct separate installation in the field. For UL Listed extinguishing system units utilizing UL Recognized Component devices, this further confirms that UL has performed the appropriate evaluation of the complete equipment.  There are several other advantages to the UL Recognized Component Program.

First, manufacturers of components are now eligible to submit their products directly to UL for evaluation. The component manufacturer specifies the intended conditions of acceptability for when these components are to be employed in the end-use equipment. This helps to apply the appropriate considerations directly to the component and limit the need for redundant testing with a system.  It also limits or eliminates the need for a component manufacturer to share proprietary construction or performance features with the end-user while still providing confidence that the minimum specifications have been met. Many of these conditions are specified on the UL Product iQ™ database for easy search.

Second, UL’s Follow-Up service for components at the OEM allows UL to determine that products remain compliant with requirements and are produced in a manner representative of the construction of the product that was originally evaluated and certified. This prevents repetition of timely and costly examination or testing at the system unit manufacturer location.  

Third, partnering with suppliers of UL Recognized Components allows an end-user to submit a complete extinguishing system unit for UL Listing without the need to become experts on every individual component and instead focus on what they do best. In fact, most manufacturers of UL Recognized Components are known specialists in their field and have long served as a go-to resource even before Recognized Components were available. The conditions of acceptability further allow an end-user to have the built-in confidence that the component has already been evaluated for the most critical aspects of certification. It can help them avoid the daunting task of purchasing and submitting samples, coordinating weeks of on-site testing, and waiting months for test results, while trying to complete the acceptance testing for the system, setting up a manufacturing location for UL Follow-Up Service and arranging for documentation review. 

Fourth, UL is now able to offer a conversion program to existing UL Listed system unit manufacturers.  Market access has traditionally been limited to sales of complete extinguishing system units and company exposure under the system unit category only. With the introduction of UL Recognized Components for systems, system unit OEMs can make their components available to a new market of global system unit manufacturers without releasing critical construction and performance details. This also increases company exposure on the UL Product iQ™ database for each component type. 

Fifth, UL’s Recognized Component Program strongly aligns with many other third-party certifications without reducing the value of the certification of the complete extinguishing system.  System unit certification with UL remains the hallmark of excellence and means a product has been evaluated, complies with UL’s requirements and is manufactured under a continuous UL oversight, meaning the certification extends beyond testing. This Follow-Up Service allows UL to determine that products remain compliant with requirements and are produced in a manner representative of the construction of the product that was originally evaluated and certified. The alignment will allow future consideration of expanding UL’s authority where local component-based requirements apply in other regions of the world.

Additionally, many purchasers, building designers and building owners understand UL Recognized Component devices are reliable. When such external parties see these devices, it can serve as a third-party quality control check. When made aware, UL will establish a field report to determine the nature of any nonconformance and take appropriate corrective action in the unlikely event that an issue would occur.

Before you ask, some testing remains unavoidable. The actual tests needed will have to be reviewed on a case-by-case basis.  In general, nozzle distribution, engineering software calculations and similar tests where the limitations are defined by the end-user are still considered proprietary. The test results are also incorporated into the system unit manufacturer’s installation, operation, and maintenance instruction manual necessitating review for certification eligibility.  Despite these challenges, the many advantages of Recognized Components are expected to lead many product manufacturers to obtain UL Recognized Component Marks for their products and maximize the acceptance by system unit manufacturers and by authorities having jurisdiction.

To learn more about our extinguishing system and extinguishing system component certification, please visit or contact


Author: Matthew D. Tennenbaum, Strategic Development Manager for Fire Suppression; UL