#16 – What is a Storz Connection and How Does It Work?

Universal, quick-connect Storz hose couplings simplify the use of large diameter hose with fire hydrants and fire department connections

Over the last century, fire departments throughout the United States have attempted to standardize the fittings they use to connect fire hoses to fire hydrants, pumps, and the inlets supplying water to fire sprinkler or standpipe systems. But one type of hose connection works particularly well with large diameter hose: the Storz connection.

In this article, QRFS explains what a Storz connection is, how it differs from other hose couplings, and how they’re used by firefighters to supply water to fire sprinkler or standpipe systems.

If you’d prefer, you can click here to skip this article and look directly at our Storz connections and blind caps.

What is a Storz Connection?

Invented by Carl August Guido Storz in 1882, a Storz connection is a type of hose coupling used to connect large diameter hose to a fire sprinkler or standpipe system. This connection quickly dominated the European fire protection market but took nearly 100 years to find its place in the United States. Today, many fire departments in the United States and Europe use Storz with large diameter hose applications.

Storz solves a common problem faced by firefighters: mismatches between couplings. The thread types or coupling standards firefighters use to connect their hose to the standpipe, sprinkler system, or fire hydrant may vary from city to city—or, in rare cases, even from building to building. Storz connections, however, are the same everywhere. A 5-inch Storz coupling on a fire hose can connect to other 5-inch Storz fittings on a fire hydrant or fire department connection.

Threaded couplings—including the National Standard Thread (NST) couplings frequently used with fire hose—are gendered. A male-threaded end only connects to a female-threaded end, and vice versa. A Storz coupling, however, has no gender. As a result, firefighters will never face the dangerous inconvenience of finding and using adapters to correct mismatched threads during a fire.


Storz blind cap and connection, side by side
A Storz blind cap (left) with a Storz connection (right).

How does a Storz Connection work?

When opposing Storz couplings are pressed together, special hooks on each coupling insert into the slots in the flange of the other. Rotating the couplings in opposite directions until they’re tight (usually a quarter turn) causes the latches to engage.

Each Storz connection contains a gasket. Turning the couplings tight causes the gasket to form a water-proof seal. To uncouple, release the latches and turn the couplings in opposite directions from each other. The couplings separate when the hooks and slots align.

Where are Storz Connections found?

Fire engines carry large diameter hose with Storz connections. These connect to a fire hydrant or directly into a fire department connection (FDC). The FDC feeds water into a building’s standpipe or fire sprinkler system, adding needed pressure or acting as a substitute water supply when normal sources of water are inoperable.

For the fire department to connect their hose to Storz fittings, there must be an existing coupling accessible on the outside of a building or on a fire hydrant. Storz FDCs come in three varieties: straight (flush), 30-degree (exposed), and freestanding.

Straight and 30-degree Storz FDCs connect to fire sprinkler or standpipe piping through an exterior wall. Straight Storz connections mount flush with the wall. 30-degree Storz features an elbow extending beyond the wall, allowing a connected hose to gradually bend toward the ground.

By far the most common is a 5-inch-by-4-inch 30 degree Storz connection. With fire sprinkler systems, these can be found on the outside wall, marked with an escutcheon that reads “Auto Spkr”. This Storz connects through the exterior wall to piping inside the building.

A Storz FDC
A Storz fire department connection with a 30-degree elbow. Source: Wikipedia.

Freestanding Storz FDCs, meanwhile, connect to fire protection systems through underground pipe, enabling installation on a sidewalk or another remote location.

Want to learn more about the basics of fire department connections? Click here to read QRFS’s need-to-know guide.

Storz connections at QRFS

30-degree and straight Storz connections are available in a range of sizes for fire sprinkler or standpipe systems using National Pipe Thread (NPT), one of the most common thread standards for plumbing and fire protection piping in the United States. These anodized aluminum connections feature 4-inch or 5-inch Storz hose connections and secure directly to the 4-inch or 6-inch NPT pipes supplying a fire protection system.



A Storz connection with black-dyed anodized coating
A 5-inch straight Storz connection for 6-inch NPT pipe.


A 5-inch 30 degree Storz connection
A 5-inch 30 degree Storz connection for 4-inch NPT pipe.

QRFS also supplies aluminum blind caps and chains for Storz connections. Each Storz coupling used as a fire department connection in an NFPA-compliant fire sprinkler or standpipe system must have a Storz cap to prevent dirt, dust, and debris from entering the system or blocking the inlet.


An aluminum cap and chain for Storz hose connections
A Storz blind cap, designed to protect Storz fittings against misuse and wear.

Click here to take a look at our selection of Storz connections and blind caps.

Questions about Storz couplings, FDCs, or caps? Call us at +1 (888) 361-6662 or email support@qrfs.com.

This blog was originally posted at blog.qrfs.com. If this article helped you find a solution, check us out at Facebook.com/QuickResponseFireSupply or on Twitter @QuickResponseFS.

1 thought on “#16 – What is a Storz Connection and How Does It Work?”

  1. HI,
    Good day!
    We required following material —
    1. Landing Valve 2”Storz Outlet as per European Standard Qty. 1
    2. Fire Hose with Storz Coupling Size 2” As per European Standard Qty.1
    This we need for approval purpose with all certificates . Once it is Approved will take bulk qty.
    Kindly arrange to share your best price and delivery lead time .
    We look forward your prompt reply.


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