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Large-Diameter Fire Hose Essential for Industrial Emergency Response

Industrial fire fighting, like the rest of the fire service, evolved from the simplest basic technology. The first motorized pumpers replaced the old horse-drawn vehicles. Then came diesel engines and large-capacity pumps. As little as 15 years ago the normal-sized pump found on a fire truck was only 1,000 gpm. As for hose, you usually found 2 1/2-inch and, occasionally, 3 inch for large flows. To deal with 98 percent of fires, that's adequate. As for the other two percent, think about it like bear hunting. If the bears are small, a small-caliber gun is all you need. But if a grizzly comes charging out of the woods, you'll wish you had a cannon ready, preferably two.

This is the challenge facing modern industrial firefighters. The bear is bigger, but the gun is often too small. As we have upgraded our plants to improve flows and amounts with regard to production, the fire water systems have been overlooked. You still find fire hydrants with 2 1/2-inch outlets fed by 6- to 8-inch fire mains. To catch up, many plants are enlarging their fire mains to 10- to 16-inches and installing large-capacity fire water manifolds that flow from 3,000 to 10,000 gpm each. With larger mains and new fixed fire pumps, plants can avail themselves of such alternate water supplies as ship channels, waste water ponds, city fire hydrants and fire boats.

In the late 1970s, 5-inch hose became standard on municipal fire trucks. The results have been unbelievable. Before, a normal pumper using 2 1/2-inch hose could flow an average of 500 to 750 gpm tops. Using large diameter hose, that average flow increased from 1,250 to 1,500 gpm. But despite these superior results, industry was slow to climb aboard the large diameter bandwagon. The normal size hose found in industry remained 2 1/2 inch. A pumper would be hooked into a hydrant with a soft suction and the 2 1/2-inch hose was laid from the hydrant to the fire. When nothing greater than 1,000 to 3,000 gpm was expected, this system was adequate. Today, that is no longer the case.

Refineries, chemical plants and other major industries have upgraded for improved greater production. Where we used to have 4-inch to 6-inch piping, we now have 8-inch to 12-inch. As a result, when we have a spill, leak or fire the size and magnitude is also increasing by the same ratio. Storage tanks went from an average maximum of 80 to 150 feet in diameter to as big as 200 to 300 feet. That increased the fire flow necessary in an emergency. Where once anything in the range of 500 to 1,000 gpm was adequate, today's plants require between 5,000 to 20,000 gpm. simple math tells us that 2 1/2-inch hose has seen its day. To flow 20,000 gpm using 2 1/2-inch hose would require 80 lines working at once.

What is the answer if a plant fire brigade needs to flow that much water? Industrial fire fighting has turned to large-diameter hose. But what size, how much and what does it take to get the maximum flow where you need it? Using large-diameter hose means more than just buying a big hose, a pump and a nozzle. It is only one part of an over-all system.

First, plant officials must determine what is the required objective of this system. The flow needed to deal with the largest tank fire is normally the highest flow available. Lets assume the maximum is 15,000 gpm. Now say that the plant fire water system is capable of flowing 10,000 gpm maximum and will require 12,000 feet of 5-inch hose. The other 5,000 gpm flow needed is available from a nearby ship channel and will require 8,000 feet of hose. So the total amount of 5-inch hose needed is 20,000 feet. In addition, flowing the amount of water needed will require a portable pumping capacity of 12,000 gpm. That means you will need three 4,000 gpm portable pumps. How are you going to deliver that massive amount of hose in a hurry? For arguments sake, lets say you have two pumpers that can each carry 2,000 feet. The rest can be handled using two trailers, each carrying 8,000 feet.

Lets take our scenario further. How about nozzles? You will need large-capacity nozzles capable of flowing a minimum of 15,000 gpm. A wide range of sizes will be needed to give the incident commander a variety of options for flowing water and foam. Among those options is the choice to use many small-capacity nozzles to achieve the large flow required. But many times we use large-capacity nozzles not only for their flow, but to achieve the extended reach that is almost always needed. For example, a 2,000 gpm nozzle has a maximum reach of 250 feet, whereas a 6,000 gpm nozzle has a maximum reach of 450 feet. Remember, if you don't get the wet stuff on the red stuff, all is in vain. Add two 6,000 gpm nozzles and two 2,000 gpm nozzles to the list.

What we have to acquire so far for this fictional system is:

? 20,000 feet of 5-inch hose.

? three 4,000 gpm portable pumps.

? two trailers capable of carrying 8,000 feet of hose each.,

? two trailers capable of carrying 2,000 feet of hose

? two 6,000 gpm nozzles.

Once we have all the toys we need you must be certain that it will work together as a system. It is foolish to purchase all the equipment listed above without first knowing if each component will work well with the other components. There is only one way to test a system - lay out the hose, hook up the pumps and connect together all the hardware. And don't forget that the system must be able to handle the require amount of foam as well as water. Test using both. If is the only way to assure that you have a system in place adequate to protect the plant from a disaster no one wants, but that we all recognize is still very much a possibility.

Now you are ready to make a purchase. Not quite. There are many variables still to consider. Take hose, for example. The size needed has been established, but what about specifications as to the quality of the hose. Not every hose is the same. There are variables to consider such as pressure rating. How and what type should you buy?

As per NFPA standards, there are two types of large diameter hose - supply lie and fire attack hose. The differences are important to realize. When buying hose it makes sense to consider what the hose will be used for. If you are going to use the hose to fight fire as hand lines, you should use fire attack hose. This hose is designed to withstand hard usage and abuse such as dragging it over rocks or concrete. It is more resistant to heat and continuous use than supply line hose. But if the hose is only going to be used to supply large quantities of water, such as a 4- to 6-inch hose or larger, and the hose is normally laid down a street to either a pumper or large-capacity nozzle, then supply line hose is what you want. This hose is designed to supply water in emergencies, not for everyday use. In particular, it should not be handled and moved after it is charged with water.


Testing of fire hose and accessories is something that is done at least every year. The NFPA Standards and OSHA both require annual service test of hose. At present there is no requirement to test fire hose accessories such as wye's, siamese, and adapters. Yet if we do not test these accessories, they may prove to be the weak link in our system. Remember, the reason to test hose is to insure that it will not fail during an emergency and possibly lose water or injure someone.

The number of injuries from hose failures has been much too great. Unfortunately, most of the injuries and deaths seem to be while testing hose. In the past year we have had three people killed while testing fire hose. Each died as a result of being struck in tyhe chest with great force by a ruptured hose. We have also had some fire fighters injured while using hose during fires, but the numbers do not seem to be as high. Therefore, it is as important to test the hose properly as it is to test it at all. The proper and recommended method to test fire hose is as follows:

1. Use of fire trucks to test hose is not recommended, but can be done. Instead, a small capacity high pressure hose tester is recommended.

2. The maximum amount fo hose that should be tested at one time is three 50 foot lengths. It should be laid out on an elevated surface with the lowest end at the connection to the hose tester. Also, it should be laid in such a manner that the operator can stand a minimum of 15 feet to the left side of the hose as measured from the inlet of the water to the hose.

3. All air should be expelled from the hose.

4. Get all kinks out of the hose and lay it as straight as possible.

5. All couplings should be marked with an ink marker just behind the coupling to measure the coupling creep on the hose.

6. Using the test pump, increase the pressure to the required amount for the service test pressure marked on the hose.

7. Do not walk over the hose or approach closer than 15 feet on the left side of the hose.

8. After all pressure is removed from the hose, check the hose coupling to insure that they did not move on the hose more than 1/4-inch from the coupling.

9. Hold the pressure a minimum of five minutes. Then release the pressure.


At present there is no recommended method to test hose appliances or accessories under any NFPA standards. All accessories that you hook to a hose system should be pressure rated to at least 200 percent of the maximum operating pressure that the system will be used at. Hose is tested to the point of failure, not accessories. Establishing a two-to-one safety factor is the normal minimum safety factor on many accessories as related to pressure.

The accessories must be tested by hooking them into a special test devices that can reach this higher pressure. The following procedures should be followed.

? 1. The adapter or hose appliance must be installed in the hose.

? 2. All air must be removed from the accessory and the hose.

? 3. All pressure that is put into the hose will be put into the hose appliances.

4. After testing, all metal parts must be inspected for any bulging or cracking. If any deformation of the metal or any cracks are found, the appliance must not be used and taken out of service.


Stortz couplings on large diameter hose has been used almost as long as we have used this type of hose. The original stortz couplings were the wire wrapped type. When we started to use the hose at higher pressures we had problems with the couplings coming off the hose. Next, hose companies in the U.S. designed another way to attach the coupling using a ring fixed to the stortz coupling with set screws. This type of hose and coupling attachment has proven to be very successful.

Another early drawback was that when the hose was laid from a fire truck, the couplings sometimes came apart when they struck the ground or when the hose was charged. The solution was a device known as the hose coupling safety latch. It is a small safety latch that must be activated before the coupling can be uncoupled. With the addition of the safety latch, the problem of hose couplings coming loose has almost been eliminated.


Why 2 1/2-inch hose became the original standard in fire fighting dates to early England in the 1700s. The earliest hose was made of leather and riveted together. In the factories where this hose was constructed child labor was used. Supposedly 2 1/2-inch hose was adopted because it was the smallest size hose that would allow a child to insert his hand inside and back up the rivet. (This was confirmed by Angus Fire Company.)

In 1892, on of the earliest NFPA standards established concerned fire hose. This standard was for 2 1/2-, 3-, and 3 1/2-inch. In 1960 the NFPA Committee recognized that newer synthetic materials were being used in 1 1/2-, 2- and 2 1/2-inch single and double jacket hose. In 1972 they recognized the concept of single jacket relay hose in 3 1/2-, 4-, 5-, and 6-inch.

Couplings on fire hose were every imaginable size and thread, creating terrible problems. In 1872 a horrendous conflagration burned most of Boston to the ground. Mutual aid responding fire apparatus were unable to connect to the Boston hydrants due to non-standard threads. The following year the International Association of Fire Engineers proposed that a standard should be adopted for fire hose threads.

Unfortunately, the fire service has never been an organization to plan ahead much. Nothing was done until 1904 when another massive fire almost burned Baltimore to the ground. Guess what? The major challenge that faced mutual responding companies was that they could not connect to the fire hydrants in Baltimore. (There is an old saying in the service -- "We celebrate a 200-year tradition unimpeded by progress.")

In 1905 the NFPA established a committee entitled "Standard Thread for Hose Couplings," which developed a standard thread for 2 1/2-, 3-, 3 1/2- and 4 1/2-inch threads. Now the challenge was to get 30,000 fire departments to change. In 1922 a standard was developed for smaller fire hose couplings. Following in 1955 a standard was developed for large-diameter hose couplings for suction hose in 4-, 4 1/2-, 5- and 6-inch size. In 1963 the NFPA accepted that some departments were using non-threaded couplings and a standard was developed for stortz couplings in 4- and 5-inch.

What you must determine is whether you plant of facility uses NH fire hose threads of some other thread? It may surprise you that many plants do not have them. To check, look at one of your couplings. If it does not have 'NH' stamped into the coupling, it most likely has some other thread.

In the early 1970s a major fire occurred at a refinery in Texas with more than 75 2 1/2-house line laid. It turned out that the refinery had non-standard threads. They had some adapters, but not nearly enough. The refinery's machine shop was busy making adapters during the entire fire with many hose lines left waiting before water could flow.


A tragic disaster occurred in 1979 in the Iranian desert when a C-130 aircraft crashed into a helicopter during the course of a secret mission to free American hostages held in Teheran. Eight American soldiers lost their lives. Full-scale military action to free the hostages suffered a major limiting factory -- water. To insure success the military would have a major challenge supplying water to the troops as they crossed that desert into Iran.

The Department of Defense started looking for solutions to the water supply problem. They contacted Angus Fire Hose Company and asked if a large-diameter hose could be constructed to supply water across a desert environment? Angus did research and came up with a flexible hose system, TWDS (Tactical Water Distribution System). The system was 6-inch large-diameter hose in 660 feet lengths connected with a Victualic coupling system. The specifications required that the hose lay flat, store easily, survive in a strong UV environment and be chemical and burst resistant. The hose also had to be approved for use as a drinking water supply hose. It then had to meet the NSF (National Sanitation Foundation) specifications for potable water under standard #61. The Defense Department purchased 1,000 miles of this hose and put it into use worldwide. In the Desert Storm conflict, the Defense Department used this system very effectively.

Similar systems have been adapted to other purposes. The Oakland East Bay Municipal Utility District uses one mile of 12-inch hose known as the Flexible Aqueduct System. It is designed to be emergency replacement for water mains that may be ruptured by earthquakes or other disasters. This system can also be used by the area fire departments for large flows. Likewise, the city of Indianapolis use some 12-inch hose for emergency water supply backup.

In turn, development of these systems led to many of the modern improvements in large-diameter fire hose manufactured today. It can be used at higher pressures and is more durable.With the improved hose at the firefighter's disposal, we are able to deliver greater amounts of water to fires than ever before in history.

The development of the Flexible Water System improved much of the large-diameter hose manufactured by numerous companies. Hose today can be used at higher pressures and is more durable. We also have better hose than ever, allowing greater amounts of water to be delivered. The evolution in fire hose continues.


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