What is the "DIN Standard" referred to in the Storz pages of the catalog?

DIN is an abbreviation for the Deutsches Institut für Normung e. V, an institution of trade and industry responsible for the preparation of National Standards in Germany.

Storz fittings were patented in Europe by Carl August Guido Storz over one hundred years ago and are now in use worldwide. DIN publishes the standards for the design of Storz fittings.

Although our catalog refers to the "DIN Standard", there are actually a number of standards that apply, one for each size and type of Storz coupling or adapter. All of the Standards for aluminum fittings are in the DIN 143xx series. For instance, DIN 14303 covers Size B (75mm) Aluminum Delivery Hose Couplings for Fire Brigade Use.

This standard specifies that the Storz head be a DIN 1725 Part 1 aluminum forging. Cast aluminum Storz fittings can be used for non-firefighting, lower pressure applications such as agriculture. In the interests of the safety of the "Fire Brigade," all Storz couplings, adapters and caps supplied by Red Head Brass are made from aluminum forgings.

What is the difference between a forging and a casting?

Forgings are manufactured by pressing metal under great pressure into parts that, as a result, have high strength. The metal is typically heated, but not melted, before forging.

In the casting process, the metal is melted before going into a mold. The metal poured into the mold solidifies as it cools. The control of the molten metal temperature is critical. Likewise, the quality of the metal being melted must be controlled so that no impurities get into the molten state.

Gases that are trapped can create porosity as the metal cools. Low casting temperature and impurities, such as sand or slag, can cause imperfections known as cold shots. Metallurgically, a casting has no grain flow or directional strength. A casting can contain many unseen defects.

Forgings, on the other hand, have no internal voids that can cause unexpected failures. The grain structure of a forging is oriented to part shape for greater strength. A forging has greater density.

In general, forgings are seen as having a higher integrity and greater reliability than castings.

What is "Hardcoat Anodize" and why do I need it?

Not all anodizing is the same. "Hardcoat Anodize" is very specific type of anodize that gives aluminum parts greater abrasion and corrosion resistance than that provided by the more conventional plain anodize processes. It is sometimes referred to as "Alumilite Hard Coat," "Martin Hard Coating," "Hard Anodizing" or "Hard Coating".

The coating is a hard aluminum oxide that is formed by the electrochemical reaction of aluminum with oxygen. It is chemically bonded to the aluminum. Hard Anodic Coatings are defined by Military Specification MIL-A- 8625, Type III, Class 1. In order to meet this specification, the coating thickness must be held to .002″ +/- 20%, pass the abrasion resistance requirement found in the specification, and be routinely tested to these parameters to insure quality.

Plain, or conventional anodize has no such requirement for thickness or wear resistance. Other coatings, for instance paint or powder, likewise have no such requirement for abrasion resistance. The threaded and non-threaded couplings and adapters used in firefighting greatly benefit from the abrasion and corrosion resistance provided by Hardcoat Anodize. It is the specification Red Head Brass follows in manufacturing its quality aluminum products.

What is a "Higbee"?

A "Higbee," also known as a Quick Start Thread, is a modification to the first thread of a hose thread.

The thread is machined back from the end until the cross section of the thread is full, in other words looks like a fully formed triangle. Mating threads go together and start quickly.

There is no partial, or thin thread to be rolled over and jam the connection.The full strength of the thread is available as soon as mating threads are connected.

On Rocker Lug parts, there is a notch in the lug adjacent to the Higbee to help locate the Higbee for ease of assembly. This is especially important for internal threads where the Higbee cannot be easily seen.

NFPA 1963 requires a Higbee on NH threads. Taper Pipe Thread, NPT, does not get a Higbee.

Will Storz fittings from Red Head Brass mate with Storz fittings from other manufacturers?

Simply put, as long as they are the same size, they should. Red Head Brass manufactures Storz fittings to meet the established dimensional standards. As long as the Storz fittings from other manufacturers meet these standards, the fittings will mate.

The 4″ and 5″ Storz connections, for example, are included in NFPA 1963. However, there are numerous sizes of Storz fittings available. Some are only metric sizes. Others are combination English/Metric sizes. Those sold domestically are very specific sizes for the U.S. market and are usually marked with the nominal size in inches. They may also be marked with both English and Metric units.

Red Head Brass currently offers 1-1/2″ (38mm), 2-1/2″ (65mm), 4″ (100mm), 5″ (125mm) and 6″ (150mm) Storz fittings.

Why is "Seamless" better than "Structural" extruded aluminum for firefighting applications?

Although they may look the same, structural and seamless tube are two distinctly different products. The two products are extruded by two different techniques.

"Seamless" is extruded from a hollow billet by the die and mandrel process or from a solid billet on a piercer press. In either case, the wall of the extruded tube never separates as the shape is extruded. This results in a uniform structure with predictable strength throughout.

Structural tubing, on the other hand, is produced by a bridge die or port hole die. The mandrel that makes the inside diameter of the tube is supported by webs. As the metal passes through the die it is separated by the webs. As the metal exits the die a mechanical bond, or weld, is created. The grain structure is often different where the weld seams are located. The weld seams run down the entire length of the tube. The seams can often be seen after anodizing. The seams take on a different color than the surrounding metal. When viewed on end, the seams appear as spokes on a wheel. There are no standard industry guidelines for weld seam quality and each producer establishes their own internal criteria. There are no published burst pressure ratings for structural tube. Manufacturers of structural tubing do not recommend its use for pressure applications. Test pressures for fire hose couplings and adapters can be in the 1000-1200 psi range.

For its quality hose couplings and adapters, Red Head Brass machines these critical components from seamless extruded 6061-T6 aluminum exclusively.

Are there different types of Storz gaskets?

In general, there are two different types of Storz gaskets, Pressure gaskets and Suction gaskets and they operate in different ways. It is important, when ordering, to specify the application so that the correct coupling or adapter, with the proper gasket, is supplied.

The gaskets, although similar, are generally not interchangeable. The Pressure gasket has a lip, or flap, that is open to the inside, facing the water. As the line is charged, the lip pushes out tighter and tighter against the lip of the gasket in the mating coupling to make a waterproof seal. The coupling torque to assemble two mating pressure couplings is small so that the couplings can easily be connected. Water may leak out until the pressure in the line rises to push the flaps together.

Suction gaskets have a flap on the outer rim, facing the outside. The coupling torque to assemble mating suction couplings is higher so that these flaps on mating couplings are pressed together initially, sealing out the outside air, so that the draft can be started. As the suction increases, the flaps are pulled together even tighter. Because of the higher connection torque, wrenches may be needed to assemble Storz Suction fittings.

Pressure gaskets are black in color. Suction gaskets are grey.

NFPA 1963 requires that Suction gaskets be installed in Storz Caps.

What is the difference between "NH", "NST", "NPSH", "IPT", and "NPT" threads?

"NH", or National Hose, thread is the thread that has become the standard thread used in firefighting today. The threads specified in NFPA 1963 are "NH". This thread was previously known as "NST" or National Standard Thread.

"NPSH", or National Pipe Straight Hose, is slightly smaller in diameter and has more threads per inch than the same nominal diameter "NH" thread. "NPSH" thread is sometimes referred to as "IPT", or Iron Pipe Thread. "NH" and "NPSH" threads are not interchangeable. "NH" and "NPSH" threads are straight threads and require a gasket for sealing between mating threads.

"NPT", or National Pipe Tapered, is the thread most commonly found in plumbing applications. Being tapered, the seal between mating threads is made by squeezing the threads together. No gasket is used. "NPT" and "NPSH" threads are similar in diameter and threads per inch.

For more information on threads, see page 31 of this catalog.

Why are tapered pipe threads (NPT) not available in swivels?

The typical coupling consists of three main components; male, band, swivel. The swivel's job is to bring together the male and the band, squeezing a gasket between them, sealing the water path.

With straight threads, like NH and NPSH, the swivel turns on the male as far as necessary to make this seal. However, NPT threaded components seal by jamming the mating threads as they are tightened. No gasket is used. The turns required to tighten may vary. If NPT threads are used in a coupling, the end of the male may not stop at the correct place in the swivel. The male can be tight into the swivel, but even with a gasket, it may not seal against the band. This would allow water to leak out of the joint. Thus, NPT threads are not available in swivels.

However, a coupling set with a NPT male and a NPSH swivel can work. NPSH thread is the straight version of NPT thread. A NPT male will screw into a gasketed NPSH swivel and seal against the band, provided the end of the male is cut square.

What kind of maintenance should be done on Couplings and Adapters?

The NFPA publishes an excellent Standard, NFPA 1962 Standard for the Inspection, Care, and Use of Fire Hose, Couplings, and Nozzles and the Service Testing of Fire Hose, that covers this subject very well. Red Head highly recommends that the Standard be followed.

Chapter 6 of the Standard pertains to Nozzles, Couplings, and Gaskets but the recommendations in the chapter apply equally well to appliances, such as elbows, wyes, and adapters, both threaded and non-threaded. In general, NFPA 1962 recommends that all of these types of items be inspected after each use and at least annually. The annual Service Testing of hose is a good time to include these inspections.

An inspection should include:

  • Waterway clear, no obstructions
  • Threads not damaged
  • Swivel rotates freely, bearing plug and bearings in place
  • No excess corrosion
  • Gaskets in place and in good condition
  • Clamp bolts on LDH coupling collars in place and tight
  • Storz head lock levers, if so equipped, in place and operating freely
  • Hose not slipping out of the coupling

In the case of connections of components made of dissimiliar metals, for instance brass and aluminum, the standard recommends that they be disconnected and inspected quarterly for corrosion. If the inspection reveals problems, the item should be fixed immediately, taken out of service and fixed, or replaced as necessary.

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