Fire Protection and Mechanical Equipment

UL Listed Sprinkler Hose: UL 2443, NFPA 13 and Approval Differences

Learn what a UL listing means for flexible sprinkler hoses, the UL 2443 and NFPA 13 requirements and the differences between UL, FM and VdS approvals.

ORFA Technical TeamUpdated: Oct 30, 20263 min read

Projects, especially sprinkler systems designed to NFPA standards, often require flexible sprinkler connections to be “UL listed”. A UL listed sprinkler hose is a hose that has been tested to UL 2443, UL’s standard for flexible sprinkler hose, and included in the UL listing.

This article explains what a UL listing means, the key points under UL 2443 and NFPA 13, and how it differs from FM and VdS approvals.

What Is a UL Listing?

UL (Underwriters Laboratories) is an independent organisation that tests products to specific safety standards and lists those that comply. Listed products appear in UL’s online certification directory, and production is audited regularly. In the USA and Canada a UL listing is a basic acceptance requirement for fire protection materials, and it is also frequently required on international projects designed to NFPA.

Key Points under UL 2443 and NFPA 13

Scope: UL 2443 covers flexible sprinkler hose with fittings for fire protection service.
Length: Flexible hose length is limited to a maximum of 1.8 m (6 ft).
Bends: The allowable number of bends and minimum bend radii are stated in the product’s UL listing.
Hydraulic calculation: The hose pressure loss is published as an equivalent length of 1″ Schedule 40 steel pipe (C=120) and must be included in the hydraulic design.
Installation: The hose must be installed according to its UL listing and the manufacturer’s instructions, using the specified ceiling fixing components. NFPA 13, 13R and 13D accept flexible hose between the branch line and the sprinkler on these terms.

UL, FM and VdS Approvals Compared

Approval	Organisation	Flexible hose standard	Typically required for
UL Listed	UL Solutions	UL 2443	Projects designed to NFPA, North America
FM Approved	FM Approvals (FM Global)	FM 1637	FM Global insured sites, international projects
VdS	VdS Schadenverhütung (Germany)	VdS approval programme	European projects designed to VdS CEA 4001 or EN 12845

For details of FM approval, see our article on the FM approved sprinkler hose.

The UL Listed Set Supplied by ORFA

The Ayvaz UL approved sprinkler hose and connection set has the following features:

Hose: AISI 316L stainless steel with stainless steel braid
Fittings: Carbon steel or stainless steel
Connection: Nipple on the pipework side, 1/2″ sprinkler adapter on the sprinkler side
Hose size: DN20 (3/4″)
Working pressure: up to 16 bar
Minimum bend radius: 200 mm

Advantages

Easier acceptance: Meets specifications and approval processes that call for UL listed materials.
Seismic resilience: The flexible design accommodates relative movement between the ceiling and the piping during earthquakes.
Fast installation: Less pipe cutting and threading than rigid drops; sprinklers are easily repositioned when the ceiling layout changes.
Corrosion resistance: Stainless steel hose and braid offer long service life.

Tip: Check which approval the project specification requires before ordering. A UL listed hose alone may not be sufficient on a project that calls for FM or VdS approval.

Applications

Hotels, offices, business and shopping centres
Hospitals, schools, libraries, sports halls
Cinemas and theatres
High-rise and residential buildings

Frequently Asked Questions

What is the maximum length of a UL listed sprinkler hose?

Flexible sprinkler hoses under UL 2443 are limited to 1.8 m (6 ft). The allowable number of bends and bend radius are stated separately in the product listing.

How is a UL listed hose included in hydraulic calculations?

The manufacturer publishes the hose pressure loss as an equivalent length of 1″ Schedule 40 pipe. The designer adds this value to the hydraulic calculation according to the hose length and number of bends used.

What is the difference between UL and FM approval?

The two approvals are granted by different independent organisations to different standards (UL 2443 and FM 1637). Which one is required depends on the project specification, the design standard applied and insurance requirements.

Conclusion

A UL listed sprinkler hose is an independently tested solution that allows flexible sprinkler connections to be accepted in systems designed to NFPA. Following the length, bending and fixing conditions in the listing and including the equivalent length in the hydraulic calculation are the conditions for a safe installation. Explore all options in our Sprinkler Hoses and Connection Sets product group.

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