Large-diameter hose (LDH) has a remarkable ability to move large volumes of water at a fraction of the friction loss encountered in conventional, smaller-diameter hose. LDH can be thought of as an aboveground water main laid into an apparatus pumping at a fire or simply as a very long soft-suction hose. The advantages of LDH are very convincing when compared side by side with smaller-diameter hose. For example, five-inch hose can flow the equivalent of three three-inch hoselines at about the same friction loss. Five-inch LDH can deliver 1,000 gpm at about six psi per 100 feet or 1,500 gpm at 15 psi (friction loss). With figures as impressive as these, someone is bound to ask, If five-inch LDH is so good, why doesn’t every fire department use it? or Even though four-inch LDH is also available, why would any department purchase it when five-inch hose flows 70 percent more than the four-inch hose?
A fire department considering LDH should carefully weigh the advantages and disadvantages of each size and then decide what is best for its needs. The selection of the type and diameter of hose should not be based on what the next town or nearest big city is using. Each department has its distinct hose requirements, depending on staffing; building construction and density; apparatus; and, more importantly, water supply.
For many departments with a strong water supply system, 21/2– and three-inch hose supply all the water they need. When hydrants have sufficient volume and adequate pressure and are spaced fairly close together, LDH may be an unnecessary expense. In other areas, four-inch LDH would be a better choice because it is less expensive, is not as heavy as five-inch hose, and takes up less room in a hosebed. Loading and deploying LDH from hosebeds designed originally for smaller hose are critical considerations. Selecting the proper hose diameter should be based on comprehensive flow tests, to determine the strength of the water supply system, and a thorough assessment of the community’s fire risk and fire defenses.
OUR DEPARTMENT’S EXPERIENCE
Miami-Dade (FL) Fire Rescue started on its LDH learning curve in 1983, and we had a lot to learn. Our department purchased its first supply of five-inch hose and issued it to engine companies that saw a lot of fire activity. It didn’t take long for those companies to realize the advantages of five-inch hose over their 21/2– or three-inch hose and to become believers in LDH.
But, it would take a while longer for those crews to learn that LDH also has some limitations and that it cannot completely take the place of 21/2– or three-inch hose. And, it would take our department years of working with LDH to gain the experience necessary to adapt our procedures, reconfigure our apparatus, and train our personnel to take full advantage of LDH and minimize its limitations.
Advantages
The advantages of our newly acquired five-inch LDH were readily apparent:
- LDH virtually eliminated the need for engine companies to reverse lay hoselines from a fire and pressurize them directly from a pumper connected to a hydrant. Many hydrants in Dade County have sufficient pressure to push as much as 1,000 gpm through hundreds of feet of five-inch hose. This allows an engine to lay a large-diameter supply line from a hydrant and position its apparatus at the fire. As a result, all of the water flowed at many fires ended up being supplied by just one line of five-inch hose.
- Forward (hydrant to fire) hoselays permitted our engines to operate at the fire scene instead of pumping at a hydrant down the street. This allowed us to use more extensively our preconnected attack lines and apparatus-mounted heavy stream devices. Also, all of the tools, appliances, and ladders on the apparatus are close at hand.
- Complicated relay operations involving more than two engines pumping “in line” could almost become a thing of the past. Consider that an engine pumping 180 psi at a source of water can deliver more than 1,000 gpm to an engine pumping on the fireground through almost 3,000 feet of five-inch hose or 500 gpm through 9,000 feet of five-inch hose. This practically eliminates the practice of spacing engines at 1,000- to 1,200-foot intervals to overcome the friction losses commonly found in 21/2- and three-inch hoselines.
Yes, the capabilities of our new LDH were truly impressive. In fact, our department fell so much in love with LDH that it equipped every engine with five-inch hose and purchased portable monitors with five-inch storz connections. Some companies even went so far as to strip all the three-inch hose from their hosebed and replace it with five-inch hose. We were so enchanted with LDH that we initially failed to realize that it has some limitations. But, like so many love affairs, the infatuation stage eventually came to an end, and reality set in.
Hard Lessons
In Dade County, it took some hard lessons to learn the limitations of LDH and make the changes in our procedures, apparatus, and training necessary to use LDH safely and most effectively. We learned the following while ascending the LDH learning curve:
- LDH can give you a false sense of security. Sure, a single five-inch supply line may deliver all of the water used at most fires, but isn’t that putting all your eggs in one basket? We now know that was a mistake. The failure of that single hoseline can cut off the entire water supply to a fire-and it can happen easier than you think. All it takes is one little Honda to ruin your whole day and have you screaming for water. LDH seems to be a magnet for compact cars with low ground clearance. An impatient or inattentive motorist who drives on your supply line will probably get stuck on the hose and end up grinding a hole in it with a spinning tire or melt through it with an extremely hot catalytic converter. Driving large fire apparatus over LDH can also cut off your water supply. As much as you try to lay LDH as close to the curb as possible, it still has a way of obstructing narrow streets, alleys, and driveways.
An apparatus driving along a large-diameter (LD) supply line can jam the hose in between its dual rear wheels and tear the hose apart. That is not to say that you can never drive apparatus over LDH; that would be unrealistic. We have learned that you can drive over LDH, but it should be done only when it is absolutely necessary and there is sufficient ground clearance. Avoid the couplings, and cross the hose at no less than a 457angle; this will prevent jamming the hose in between the dual rear wheels. Also, avoid laying LDH directly below an apparatus’ exhaust because it can melt a hole in the hose. And, watch those outriggers! We learned early on that a stabilizer jack can be a very effective hose clamp when it is lowered on a supply line.
Of course, a single LD supply line connected directly to a hydrant cannot possibly meet the water flow requirements of every fire. We learned this lesson at large fires when we used long hoselays or any time hydrant pressure alone was insufficient to push the necessary gpms through the supply hose. When the demand for water exceeds the available supply, fire control becomes doubtful, and cavitation and pump damage become real possibilities. Strong hydrants can also fail to supply sufficient water flow: Although five-inch hose can flow an impressive amount of water, one five-inch supply line may not tap the potential gpm available from a hydrant.
The Four-Way Valve
 (5) The second company (TelesqurtT) apparatus pulls its supply line to the same hydrant. |
We have learned the hard way never to rely on a single supply line when lives and property may depend on an uninterrupted water supply. Also, we now use a four-way hydrant valve to help achieve the flow potential of weak and strong hydrants. Remember, however, that the four-way valve cannot “make water”-the water supply has to be there in the first place. The four-way valve allows an engine company to lay a supply line from a hydrant to the fire, connect it to the intake of the pump, and receive water with hydrant pressure. Then, if more water is needed, another engine can go to the hydrant, connect its suction hose and a discharge line to the four-way valve, and use the pump to boost the pressure in the supply line. If more water is available (as indicated by the residual pressure reading of the compound gauge), the engine connected to the four-way valve can pump additional lines. A ball valve and clapper inside the four-way valve allows an engine to receive water from the hydrant and increase the pressure without interrupting the flow to the initial supply line.
 (6) A firefighter of the second company connects the TelesqurtT’s supply line to the four-way valve. |
Although a four-way valve helps to maximize the flow of five-inch hose, it is even more beneficial to departments using four-inch hose. An engine boosting pressure using a four-way valve helps to overcome the friction loss in four-inch hose with long lays or with high gpm flow.
 (7) switches the valve to supply both lines (without interrupting the flow to the first line). |
A four-way valve also makes an expedient hydrant gate valve, permitting two supply lines to be connected to the same hydrant without shutting it down to make connections. Connecting two LD supply lines helps to take greater advantage of the potential gpm available from a hydrant. A four-way valve used in this manner can effectively supply two engines when no other hydrant is available, provided the following factors are considered.
- The hydrant is capable of flowing substantially more water than one LDH supply line can achieve. Check the compound gauge of the engine on the first supply line-a relatively high residual pressure (above 40 psi) will indicate if more water is available for a second supply line.
- Both engine companies coordinate and communicate the amount of water they pump to ensure that they don’t “steal” water from each other.
- Finally, be realistic. If your goal is to supply two engines to their rated capacity with one hydrant, you are either a wishful thinker or you have an extremely strong water supply system. This evolution is ideally suited to fires in large scrap yards or for exposure protection: In other words, you have a need for two engines to operate at different ends of a fire, but each is pumping a limited amount (less than 1,000 gpm).
Pressure Limitations and Weight
LDH can have pressure limitations. Many fire departments purchase LD supply hose, which has a maximum operating pressure of 185 psi. We learned that occasionally our LD supply hose could not be pumped at the high pressures needed to supply standpipes, elevated streams, or foam systems. (LD attack hose must be used in these cases.)
LDH is big, bulky, and heavy: A 100-foot coupled section of five-inch hose weighs about 115 pounds. That weight isn’t much of a problem as long as LDH can be laid directly from an apparatus and reloaded by driving/backing along the hose. But, what about handstretching and picking up LDH where apparatus can’t drive? I feel sorry for the firefighters who must stretch LDH down a rail siding to reach the rear of a warehouse; they’re in for a workout.
Weight became even more of a problem when we purchased the ground monitors with five-inch intakes. Now, we had to drag out LDH to supply a monitor that could be hundreds of feet from an apparatus. A charged section of five-inch hose contains approximately one gallon of water per foot. At 8.35 pounds/gallon/foot, it’s no wonder that five-inch hose is so difficult to reposition once it is charged. We now emphasize in training the importance of moving the LDH into its final position before charging: close to the curb, out of traffic, and with kinks and twists removed.
HANDSTRETCHES
 (12) The second firefighter in the stretch “shoulders” the coupling at the 100-foot point and begins dragging. |
It took a few years for us to rethink our procedures for handstretching LDH. We now have much more realistic expectations of how long it takes to handstretch five-inch line and the number of firefighters it will take. These are critical considerations for an incident commander whose strategy depends on stretching LD hoseline before his defensive position is overrun by a rapidly spreading fire. As a practical matter, expect one firefighter to drag no more than 100 feet of LDH. How fast he accomplishes this task depends on obstacles along his stretch and what he is expected to do when he is finished stretching the line. If he can sit, lie down, and rest (unlikely in most departments), he can operate at a fast pace. But, if you expect your firefighters to accomplish other tasks after stretching LDH, you’d better not wear them out by having them move too quickly. Stretching LDH any significant distance will probably require the combined personnel of several companies.
Guidelines for Stretching LDH
 (14) Begin by placing the end of the hose to the side of the rear step and then pulling the hose, hand over hand, 25 feet behind the apparatus. This will form a loop consisting of 50 feet of hose. |
Following are some guidelines for handstretching LDH safely and effectively.
 (15,16) The first firefighter in the stretch shoulders the end of the hose and the 50-foot loop while his partner pulls the second loop. |
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Apparatus position. If possible, always position the apparatus so that the rear of the hosebed faces the direction in which the hose will be stretched. This may require turning the apparatus around and “backing down.”
- The running stretch. When LDH can be pulled straight out of the hosebed and dragged in a fairly straight line behind the apparatus, it is most easily advanced using the running stretch: The first firefighter on the line begins the stretch by simply grabbing the end of the LDH from the hosebed and dragging it behind the apparatus. The next firefighter in the stretch helps pull hose out of the hosebed until the first coupling leaves the hosebed at the 100-foot mark; then he takes this coupling and starts dragging the next section. All other firefighters in the stretch stand by at the rear of the apparatus, help clear the hosebed, and await a coupling to start dragging the hose. The key is to make sure everyone places the hose over the shoulder with the coupling in front of the body.
(15,16) The first firefighter in the stretch shoulders the end of the hose and the 50-foot loop while his partner pulls the second loop.
Never allow LDH couplings to drag on the ground. They’re big and heavy and are bound to catch on something. The running stretch doesn’t require a lot of skill or training, just some strong (real loud) direction, especially when there aren’t enough firefighters and you have no choice but to rely on police officers, postal workers, or others to help with the strech. Note: This is only a last-resort option.
- Stretching around corners. Handstretching LDH around corners and obstacles can be very difficult. The amount of hose each firefighter can physically drag depends on many variables, including the length of the stretch, the size of the hose, the weather, the terrain, and the corners and obstacles encountered. A particularly difficult stretch may limit a firefighter to only 50 feet of hose. Since the LDH will not be advanced in a straight line, it should be arranged in a series of loops 25 feet long, each loop consisting of 50 feet of hose. This reduces friction with the ground and makes it easier to maneuver the hose around obstacles and corners.
(17) The next firefighter in the stretch shoulders the coupling and fold at 50 feet of the next section.
Begin by placing the end of the first section of hose on the ground at the side of the apparatus back step. Now, pull the hose, hand over hand, as you walk back 25 feet behind the apparatus. This will form a loop consisting of 50 feet of hose. Next, you or a partner pulls another hand-over-hand loop in the same fashion until the coupling connecting the first and second 100-foot sections drops out of the hosebed. Now, shoulder the end of the hose and the fold at the 50-foot mark, and begin your drag. Additional sections are pulled and advanced in the same way, with each firefighter shouldering a coupling and fold of hose at the 50-foot mark.
- Encountering obstacles. Personnel dragging LDH must work as a team and communicate with each other if the hose “hangs up” on an obstacle. The last firefighter in the stretch will be the first to feel the hose tighten as the slack begins to pull out. He will then drop his coupling and loop, remove any kinks and twists, and then help “lighten up” the firefighters stretching the length in front of him.
- Pace yourself. When handstretching LDH, firefighters must pace themselves according to the number of personnel available and the urgency of the situation. Be realistic. This isn’t a 13/4-inch attack line. You’re not going anywhere in a hurry; otherwise, you risk injury and sheer, incapacitating exhaustion.
- Wear appropriate clothing. Firefighters advancing LDH on a hot summer day will soon feel the effects of the heat and humidity. You may look safe in full protective clothing, but actually you’re in danger of suffering heat exhaustion. Unless in a danger zone, firefighters advancing LDH in hot weather should strip off their coats and SCBA tanks.
THREE-INCH HOSE RESTORED ON APPARATUS
 (18) The last firefighter in the stretch drags the hose until there is no slack between him and the apparatus. He then drops his coupling and the fold and straightens his length. |
The difficulties we experienced in handstretching LDH eventually led to restoring three-inch hose on the apparatus from which it had been completely removed. Removing the three-inch hose was, of course, a mistake. Not only is it easier to stretch but it can be pumped at higher pressures than LD supply hose. Also, if three-inch hose can deliver the desired flow, why take the time and effort to handstretch LDH?
A portable monitor with a storz inlet for LDH is fine when it can be operated close to the apparatus supplying it, but handstretching LDH to a monitor hundreds of feet away is a labor- and time-intensive operation.
 Supplying a portable monitor fitted with an LDH inlet with three-inch hose. (20) It is much easier to stretch three-inch hose than five-inch LDH, especially over long distances and obstacles. |
After watching his men struggle to handstretch hundreds of feet of five-inch LDH to a portable monitor, a chief in my battalion devised a much easier method of supplying our monitors fitted with five-inch storz inlet connections: Connect a 15- or 25-foot “pony” section of five-inch hose to the monitor and connect a three-inlet 21/2-inch NST 2 five-inch storz gated ball valve to the hose. Now, the monitor can be supplied by three-inch hose.
 (21,22) Adapt a five-inch storz monitor by connecting a three-inlet 21/2-inch 2 five-inch storz ball valve to a short “pony” section of LDH. |
Typically, we will stretch one line of three-inch hose to the monitor and start water flowing through a 11/4- or 13/8-inch tip. Sometimes, just one three-inch line is sufficient. If more water is needed, we’ll stretch another three-inch line. Once a second three-inch hoseline is connected, we will momentarily close the ball valve, change to a 13/4- or two-inch tip, and then flow as much as 1,000 gpm.
 (21,22) Adapt a five-inch storz monitor by connecting a three-inlet 21/2-inch 2 five-inch storz ball valve to a short “pony” section of LDH. |
The short section of LDH, filled with water and laid in a straight line behind the monitor, acts as a substantial anchor, stabilizing the appliance against nozzle reaction forces.
PICKING UP LDH
 (23,24) Start flow to the monitor through a 13/8- or 11/2-inch tip with one three-inch line. That may be sufficient to control the flow at the ball valve. (Photos by Arnold Gantz.) |
Picking up LDH after a fire is not easy. One Christmas morning, my company had to relieve the previous shift at a particularly nasty fire in a huge scrap yard. By that time, everything was ankle-deep in mud. Dragging the five-inch hose back to the apparatus was sloppy, slow, and miserable. Fortunately, firefighters are great innovators and always manage to figure out the easiest way to get the job done. In this situation, someone had the idea of rolling up the LDH and then inserting a five-foot pry bar into the middle of the roll. Now, the roll can be easily lifted and carried by two firefighters, one at each end of the bar.
LAYING OUT FROM SMALLER HOSEBEDS
 (23,24) Start flow to the monitor through a 13/8- or 11/2-inch tip with one three-inch line. That may be sufficient to control the flow at the ball valve. (Photos by Arnold Gantz.) |
Laying LDH out of a hosebed originally designed to carry 21/2- or three-inch hose can be difficult, dangerous, and-on some apparatus-impossible. LDH is big, takes up a lot of room in a hosebed, and has large storz couplings that tend to jam in the hosebed or “hang up” on steps, grabrails, spotlights, or anything that projects from the rear of the apparatus.
 (25) If more water is needed, stretch a second three-inch line. |
The problem was worse on our TelesqurtT apparatus because the rear of the hosebed is partially obstructed by an aerial turntable. Some departments are combining engine and ladder functions by purchasing quints. Many quints have a problem deploying LDH because the hose must pass through narrow chutes on either side of a rear-mounted aerial turntable. Take nothing for granted. When you load a new or existing apparatus with LDH for the first time, take it out to a parking lot and repeatedly lay the hose out. Lay it fast, lay it slow, lay it while taking extremely sharp left and right turns. Watch for hose that jams in the hosebed or couplings that catch on grabrails and on ladders or that wedge against a turntable.
 (26) Connect the second three-inch line to the ball valve. |
Be extremely careful when loading LDH. It must, of course, be laid flat, and all couplings must be able to be pulled freely without flipping over (use a Dutchman, if necessary).
 (27) Momentarily shut down the monitor at the ball valve to change the tip. |
Load the couplings sequentially so that one coupling doesn’t have to pass over another when pulled from the hosebed. Start by placing the first couplings in the hose load at the rear of the hosebed; then work toward the front.
 (28) Both three-inch lines are supplying the two-inch tip at more than 1,000 gpm. (Photos by Arnold Gantz.) |
If the apparatus has a rear-mounted aerial device, load the couplings to the extreme sides of the hosebed, opposite the turntable, to prevent them from binding against the aerial device. LDH with air trapped inside resembles an air mattress. When space in the hosebed is a concern, air and any water remaining in the hose can be evacuated by capping one end of the hose and draining toward the open end. Water flowing to the open end of the hose creates a vacuum that tends to suck the hose flat.
AVOIDING INJURIES
 (29) A 100-foot roll of five-inch LDH, which weighs about 115 pounds, can be easily carried back to the apparatus by inserting a long pry bar into the middle of the roll. |
We were fortunate that our procedures for laying LDH didn’t cause any serious injuries. When we began using five-inch hose, we continued to “wrap” (anchor the supply line around) the hydrant when beginning a forward hoselay, just as we had always done with 21/2- and three-inch hose. Occasionally, the LDH would “hang up” as it was being laid and uncoil from around the hydrant with tremendous force. Luckily, the hydrant man was paying attention and fled before he was crippled by a flying coupling. Also, up until a few years ago, a firefighter would ride the apparatus back step while laying a line. His job was to count couplings (number of sections of hose) and signal the engineer to stop the apparatus if the hose should hang up. We learned to no longer place our firefighters in positions where they could be struck by a coupling or recoiling hose. Now, the hydrant man secures the end of the supply line by folding the coupling over and stepping or kneeling on the hose. Some departments use a strap wrapped around the LDH that can be looped over a hydrant. The strap should be strong enough to anchor the supply line but should be equipped with a plastic buckle that will break if the hose should severely hang up. Also, no one rides a tailboard anymore, under any circumstances.
 (30) If the apparatus has a rear-mounted aerial device, load all LDH couplings to the extreme sides of the hosebed to prevent them from catching on the turntable. (Photos by Enrique Perea.) |
LDH is most vulnerable to hanging up at the very beginning of a hoselay and when the apparatus must make a sharp turn. To avoid these trouble spots, begin a forward lay evolution with the apparatus stopping 20 to 30 feet past the hydrant. This permits the hose to be pulled almost straight out of the hosebed without catching on floodlights, grabrails, or ladders. If you must take a sharp turn, stop the apparatus and have a firefighter lay the hose in a smooth arc around the corner. Also remove any twists that can be a big problem when LDH abruptly changes direction. Multiple twists must be removed before LDH is charged. Otherwise, it can violently untwist as it fills with water. I’ve seen heavy LDH manifolds whip and flip over with tremendous force as the hose aligns itself in the same plane. Also, older LDH (not equipped with locking couplings) can become disconnected at the hydrant or pump intake as it untwists.
 (31) Companies that anchor their LDH by “wrapping” the hydrant risk injury if the hose should “hang up” in the hosebed. |
Part 2 will discuss forward and reverse lays, manifolds, and other approaches that add to the versatility of the hoselay.
 (32) It is much safer to “heel” the supply line by stepping on it |
Thanks to Chief Dave Brooks, who provided technical assistance for this article.
BILL GUSTIN is a captain with Miami-Dade (FL) Fire Rescue (formerly Metro-Dade) and lead instructor in his department’s officer training program. He began his 27-year fire service career in the Chicago area and teaches fire training programs in Florida and other states. He is a marine firefighting instructor and has taught fire tactics to ship crews and firefighters in the Caribbean. He also teaches forcible entry tactics to fire departments and SWAT teams of local and federal law enforcement agencies. Gustin is the author of the video Fighting Car Fires (Fire Engineering, 1998), and the forthcoming video Search and Rescue in Private Dwellings. He is an editorial advisory board member of Fire Engineering.
 (33) kneeling on it-with the coupling away from the body |
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