Returning to the foundations: Fire hose


CarolinaFireJournal - By Mike Coffey
By Mike Coffey
08/04/2013 -

Since a lot of what we do deals with water as the main medium for fire attack, delivery of said water to the combustion process involves hose of different kinds for different applications involving moving water from the supply to the apparatus pump, then from the pump to fire attack crews staffing hose lines. Different construction features involving different materials allow water to be delivered anywhere on the fire ground. Connections with couplings make connecting hose sections to each other and pump outlets or standpipe outlets possible.

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I got to see a lot of equipment while I was there, and there were some companies that were introducing new products. One of those products was the new “Super X” strut from Res-Q-Jack. I have written a couple of articles over the past 10 years on their products, from the RJ3s to the newer Steel X Strut. The RJ3 was the original strut that revolutionized the industry, and brought us into a much safer way of stabilizing vehicles. The Aluminum X Strut came next which offered a stronger capability with the loads being handled. Then along came the Steel X Strut with the detachable jack, allowing the rescuer to move the jack to other struts. Now it’s the Super X Strut giving the rescuer more capability than ever while being easy to use.

The Super X Strut comes with the detachable jack again allowing the rescuer to move it to another strut. This offers more capability for less cost, as you do not have to have more jacks to accomplish the same thing. All of the other struts feature a pin system for raising and adjusting. These pins are pulled and then reset once the strut is where you want it to be. The new Super X uses a rotating collar to adjust the strut, eliminating the pins altogether. This gives you less to keep up with and makes it easier to operate. These struts use a round tube rather than the square tubes used on all the other struts. The adjusting tube is threaded with a collar to allow the jack to be used for lifting. It uses the same multi-functional head that gives the rescuer a 90 and 45 degree angle, a steel tube point for catching the holes in uni-body frames, and a chain slot. The head also rotates 360 degrees so there is no need to remove it.

The heads can also be changed out for angled heads that can be used in structural collapse. The base allows the strut to pivot like the other struts from front to back and it has two D-rings for connecting straps. These struts however, do not have the attached straps like the Steel X and the RJ3s. A separate strap can be used for the same purpose.

The kinds of hose used in our part of the world are broken down into six major categories: attack, supply/relay, occupant-use, forestry, suction and booster.

  • Attack hose is the broadest category used and defined as any hose used to directly control and extinguish fires.
  • Supply or relay hose moves large amounts of water between a pump and a pressurized water source or used as a conduit between water sources and further divided into medium (2½” or 3”) and large diameter (3 ½” to 6”) hose.
  • Occupant-use hose is associated with building or shipboard standpipe systems for occupants to battle incipient stage fires.
  • Forestry hose predominantly found and used for forest fire and wildland fire settings.
  • Suction hose is to be used to connect pumpers with water sources — hard suction hose is used in drafting operations, although some time back (before large diameter hose) sections of soft suction hose were made to connect to hydrants.
  • Booster hose is non-collapsible and pre-connected to reels, built with elastomeric or thermoplastic tubes and covered with braided or spiraled reinforcement, then protective covers. Their use is limited to small incipient stage exterior fires.

Another type of hose encountered is extinguisher hose found on wheeled units, stationary units or vehicle-mounted units and designed to handle 400 psi (conventional) up to 1250 psi (high-pressure).

The National Fire Protection Association standard 1961 Standard on Fire Hose determines all methods used in the construction of hose. This provides uniformity and safety for effective fire ground use. The standard also dictates all components of hose including diameter, length, reinforcement, linings, coverings and markings. The diameter of hose is measured by the internal diameter of hose and must be that size — three inch must be three inch internal diameter. Construction methods vary to several basic methods: woven-jacket, rubber-covered, impregnated single-jacket, non-collapsible intake, flexible non-collapsible intake and flexible non-collapsible clear intake. Each has its own advantages and disadvantages. The standard also defines that all hose is to have coverings (jackets) made of rubber compounds of nitrile base, thermoplastic materials, blends of rubber compounds and thermoplastic materials or natural rubber-latex-coated fabric then reinforced with natural fiber threads, synthetic fiber threads or a combination of both. NFPA 1961 also defines how the threads are woven, even down to where the knots are to be placed.

The NFPA requires hose to be marked indelibly (permanently) with letters and numbers at least one inch high with the manufacturer’s identification, month and year of manufacture and the words “SERVICE TEST TO (whatever the service test pressure is) PSI PER NFPA 1962.” These markings must be in two places beginning at five feet from the ends of the hose section — traditionally 50 foot or 100 foot lengths — or at 12 foot intervals if continuously printed along the hose length. No other markings are allowed that refer to pressure other than what the manufacturer puts into the jacket. These markings refer the end user to NFPA 1962 Standard for the Inspection, Care and Use of Fire Hose, Couplings and Nozzles and the Service Testing of Fire Hose for the proper testing and care of in-service hose.

Departmental markings shall not interfere with the NFPA required markings. Supply hose meeting the Supply Hose section of the standard shall be marked indelibly lengthwise along the center line of the hose in letters two inch high stating “SUPPLY HOSE.” Supply hose meeting the attack hose requirements shall be marked “ATTACK HOSE” with the same two inch high letters.

Couplings join hose sections into continuous lengths. The couplings can be sexed (male and female) or sexless (quarter-turn or Storz). They are made usually one of three ways: extruded by pushing metal through a die, cast in molds or drop forged from a malleable (soft) metal shaped in a die by pounding the metal into the desired shape. Sexed couplings are the oldest hose connections with the male coupling cut on the outside and the female coupling cut on the inside of a swivel allowing for the connection to take place. They connect to the hose at a point called the shank. The lugs can be recessed into the coupling, molded with a pin lug or a rocker lug and are used to tighten couplings against rubber seals to limit or prevent water leakage.

The rocker lugs have a groove machined into them called the Higbee cut to indicate where the threads begin to make the connections start and thread together, therefore preventing cross threading of the couplings. Quarter-turn couplings use hook-type lugs are grooved on their underside, which extend beyond the lip at the open end of the coupling. They also use gaskets to limit water leaks.

Storz couplings are usually found on large diameter hose and are similar to the quarter-turn couplings, but they use internal grooved locking lugs to couple rather than the external lugs that typical quarter-turn couplings use. Quarter-turn and Storz couplings offer quick connections without spanner wrenches — although still recommended in some situations — eliminates cross threading and adapters — the double male and double female couplings. Their disadvantages offer the possibility of becoming uncoupled (where NFPA 1963 Standard for Fire Hose Connections requires a positive locking device on non-threaded coupling systems), adapters are required with hydrant and building appliance connections — some agencies have switched to permanent sexless connections on hydrants, sprinkler and standpipe connections — and with the lugs positioned where they are — the possibility of dirt and larger debris trapping within them allowing what seems to be a tight connection, but in actuality, no connection is made.

Couplings are attached to hose in several ways: use of expansion rings, screw-in expanders, collars, tension rings and bands.

Use of expansion rings is the oldest method and uses a ring placed inside the hose end and pushed into the coupling bowl with the ring expanding as a device pushes the ring into place. The hose is pressed tightly between the surfaces, preventing most slippages.

Booster hose utilizes screw-in expanders integrated into the coupling ends and has two pieces: the shell and expander. The shell’s serrated inside surface is to prevent slippage of the attached hose. One end of the expander has coupling threads, while the other end is also threaded and screwed into the hose and coupling shell until it seats against the face of the shell, preventing water leaks.

The collar method, usually found on large-diameter hose (rubber covered or synthetic-covered with Storz couplings), has a design fastening to hose using a collar that bolts in place. The only tool required here is the proper wrench to loosen and tighten the coupling back in place on the hose. One end of the coupling is serrated, while the two- or three-piece collar is fastened to compress hose into the serration holding the coupling in place.

The tension-ring method uses a flange ring, a tension ring and a clamp ring attaching hose to a twice-grooved coupling shank that is around the outer circumference of the shank. A nylon sleeve matching the grooves is placed over the hose end and the tension ring placed over that. As the Allen-head bolts tighten, the sleeve ridges and hose are pressed into the grooves on the shank and fitting is attached.

Banding involves couplings found in industrial applications that special circumstances challenge the uses of the other methods. This form of coupling construction is rare in the fire service. This construction method places the coupling shank inside the hose, steel bands or wound narrow-gauge wire bands use grooves machined into the shank and tightened into the grooves to prevent detachment under pressure.

Construction of the most widely used tool we have, its uses and coupling methods are part of the daily use of hose. Understanding how the differences affect our operations makes the jobs we do more efficient and safer for all involved. Enjoy the vacation season and be safe!

Captain Coffey currently serves as one of the training officers of the High Point Fire Department. He has been an instructor with the NC Community College system and the Office of the State Fire Marshal since 1990. He can be reached at [email protected].
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