Storz Couplings— an old idea that’s still going strong

Storz Couplings— an old idea that’s still going strong

The “revolutionary” Storz coupling was invented before the turn of the century.

The revolutlonary Storz coupling was actually granted a patent in 1890. Shown above is the original working drawing of the inventor, Guldo Storz.

EQUIPMENT

At 7:24 a.m. on November 9, 1872, Box 52 was pulled for what is still known as The Great Boston Fire. The Boston, MA, Fire Department, equipped with horse-drawn units, was slow responding due to a horse illness of epidemic proportions.

Mutual aid was willingly provided by towns and cities up to 50 miles away.

Connecticut, Maine, New Hampshire, and Rhode Island units, plus those from Massachusetts, totalled 45 engines, 52 hose wagons, and three ladder trucks with 1,689 firefighters to man them.

Arriving units soon found their efforts stymied by an inability to couple hoses due to thread and coupling diameter differences. Each unit was forced to operate independently and in many cases was unable to utilize Boston’s hydrants.

Less than a year later, what is now known as the International Association of Fire Chiefs (IAFC) convened in Baltimore, MD. During the first session of their organizational meeting, a resolution was introduced directing that a study be made with the objective of adopting a standard coupling that would permit fire departments throughout the country to operate together at large fires and conflagrations. The resolution was adopted and a committee was appointed immediately (known today as the National Fire Protection Association’s Committee on Fire Hose, which includes nozzles, couplings, and gaskets).

Yet, 111 years later, our technically advanced country does not have a universally used standard hose coupling. Thanks to dedicated and untiring efforts by retired Battalion Chief Bob Ely of the San Diego Fire Department, all California units operate with attack lines using National Standard Thread (NST) couplings. California permits the use of quick couplings in 3 1/2-inch sizes or larger. Some other states have similar legislation.

In areas lacking such regulations, mutual aid operations mandate the use 6f adapters. When adapters are combined with fittings usually associated with threaded couplings, we have a substantial weight, cost, and space problem plus the serious possibility that the correct fitting will not be available.

While all these problems were being discussed by an emerging IAFC, Guido Storz was working away at his drawing (continued on page 28) board in Germany. In 1882, his sexless quick coupling was first shown in Germany and was adopted by some German fire brigades as early as 1887. In March of 1890, a patent (figure 1) was granted to his employer, Zulauf & Company of Frankfurt, now known as Renus Armaturen GmbH. “System Storz” couplings were displayed at IAFC’s 25th anniversary meeting in 1898 in the United States, but the association’s committee felt the design was “not desirable.” One wonders if that committee might have suffered from a bit of “not invented here” syndrome. Interestingly enough, there is a rivetted leather playpipe with a Storz coupling attached on display at San Francisco Fire Department’s Pioneer Museum. It is marked “Storz Patent 1901,” which may have referred to a U.S. patent.

(continued from page 26)

Referring to figure 1, it can be seen that Storz’s design features a self-energizing seal and working surfaces that are protected from damage even when in an un-coupled mode. Storz couplings are not easily damaged to an inoperative state, and minor cuts, burrs, etc., are easily eliminated by filing. Storz’s original design called for a working pressure of 16 bar or 235.2 psi and a test pressure of 25 bar or 367.5 psi. These pressures remain unchanged. Referring again to figure 1, we find that special seals are available to permit coupling use on suction hoses.

Wire bindings were utilized in the original design, and this method of hose retention is still widely used today. However, the wire binding method makes it difficult to re-couple in the field and it was not well received by American firefighters.

American vendors have developed simpler methods for attaching couplings, most utilizing two or more bolts and requiring simple tools and assembly techniques. In the event of an accident, all presently used coupling attachment methods permit the hose to burst before the fitting separates.

As might be expected with a new and radically different coupling from another country, a certain amount of confusion arose regarding the interchangeability of Storz couplings obtained from different suppliers. For many years, Storz couplings have been and still are referred to as “¼ turn,” Storz and V turn being essentially interchangeable in many people’s minds. “Quarter turn” terminology probably derived from 25 mm or nominal 1-inch fittings, which take V4 turn to lock and were probably first produced in quantity. In actual operation, 2-, 3-, and 4inch fittings take V3 turn to lock while 5-inch fittings require V turn. Most importantly, it should be noted that, size for size, all Storz fittings will functionally interface, though they may be tight or loose depending on the supplier.

Although not always needed, spanners should be available to operating personnel. Storz components are actually manufactured by three German companies, including Zulauf’s successor, but are available from many suppliers worldwide. Interestingly enough, while visiting an engine company in a large metropolitan department, I saw 4-inch hose supplied by three American vendors utilizing Storz couplings held on by four different methods and all on one apparatus.

Some Storz fittings may have markings on them such as ZP 343, DIN 14303, or STORZ 125, and may additionally have a manufacturer’s trademark. ZP stands for Zentrale Prufstelle or Central Testing Station, while the number refers to a test document. DIN numbers refer to Germany’s system of industrial standards. It is translated Deutsche Industrie Norm, and is comparable to our term NST. Storz 125 simply means 125 mm or nominal five inches.

Storz couplings, used with Germanmade 4-inch hose, began to appear in the United States in the 1960s, pioneered by the Jaffrey Fire Department in Scottsdale, AZ, and the Union City Fire Department in Pennsylvania. These departments’ early efforts led to the formation of dealer/manufacturer organizations, and the development of suitable control valves, manifolds, pressure relief devices, and threaded adapters, permitting safe operations while establishing an above-ground water distribution system under emergency conditions.

It was discovered that some of the earlier Storz couplings had lugs that did not consistently line up in the fully coupled position (see figure 2). Some departments began taping couplings that were fully engaged as a means to prevent any possibility of disengagement before hoses were pressurized (see figure 3).

Storz couplings that are now being furnished by American suppliers have lugs that line up, providing visual indication of full engagement. Lugs can easily be felt with gloved hands and under reduced light or heavy smoke conditions. Experienced personnel recommend that succeeding lengths of hose be rotated slightly counter-clockwise as they are loaded so that any torque generated during charging will tend to rotate couplings in a tightening direction. For those couplings that are connected at the pump and hydrant, a greater amount of torque may be generated as the hose is charged. A new device, known as a B-lock, has been developed that functions as a positive mechanical lug lock.

Figure 2. Earlier couplings had lugs that did not line up fully in the coupled position.Figure 3. Some departments began taping couplings that were fully engaged to prevent the possible disengagement before hose lines were pressurized.

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