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One for the Little Guys

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The information provided in this article will show how 1¾-inch and 2-inch hose can be used for high-rise firefighting under specific conditions. Note: It’s not my intent to say that one size of hose should be used over another. In fact, I believe there’s a reason to bring both a 2½-inch and a smaller 1¾-inch or a 2-inch line up to the fire floor of a high-rise building. The 2½-inch will work every time-or will at least flow the most water every time.

So why take a chance using the smaller handline? This is where personal choice comes into play. If the fire can be handled with a smaller handline and the system pressure will allow it, then why not use it, making it easier for firefighters to deploy the attack lines?

Figure 1: The results of a flow test with 1.88″ hose. SRP = standpipe residual pressure, NP = nozzle pressure, BP = base pressure, and GPM = gallons per minute.

Why 2½-Inch?
Under normal fireground conditions, the 2½-inch handline has a one main purpose: flow large volumes of water for large fires. When it comes to high-rise fires, the 2½-inch can also be needed for large fire applications; however, the main reason for using the big line is to counter the large amount of pressure loss within the plumbed fire protection system of the building itself.

High-rise classes often demonstrate how various sizes of handlines work under simulated high-rise system pressures. The line that is to be analyzed is connected to the discharge of an engine company and the pump operator throttles up to a simulated system pressure. The handline is flow tested and evaluated for stream quality to verify whether it will perform under the restricted pressure conditions.

Figure 2: The results of a flow test with 2″ hose.

Example: When simulating a pre-1993 fire protection system, the correct residual pressure to use is 65 psi. The line is connected to the discharge and the pump operator throttles up to 65 psi on the discharge and the evaluation takes place. What this type of test will prove is that small handlines do not perform well under the 65 psi pressure. When the 2½-inch line is connected to the same discharge at the same pressure, however, it proves that the 2½-inch, even under low pressures, will still produce a satisfactory stream that can be used under certain fire suppression conditions.

Figure 3 The results of a flow test with 2½” hose.

Figures 1, 2 and 3 show these exact tests and their results: Flows increase significantly with the 2½-inch. This is why it’s a very popular size to be used in a high-rise application. But remember: The trade-off is a hose that is more difficult to deploy. Don’t get me wrong; well-trained departments have had excellent success using the 2½-inch handline. But it is a different tactic than your ordinary hoseline deployment and it requires consistent practice.

The Binions Horseshoe Hotel in Las Vegas features a 500-gpm/65-psi system. We used this facility to conduct tests showing that smaller handlines can produce adequate flows under certain high-rise conditions.

Testing the Theory
One limitation of the above-mentioned tests: They don’t demonstrate the actual residual pressure left over in the building system after flowing the tested flow from a handline, or the actual flow that is available from the handline under real fire protection system conditions.

The 65 psi used in the above-mentioned engine test is basically a given pressure. It’s not the real residual system pressure. Let’s use the pre-1993/65-psi residual pressure for an example again. Remember: The 65-psi number is based on a 500-gpm flow. In the flow tests conducted from an engine discharge, you can measure the simulated standpipe pressure flow at the 65-psi pressure and come up with an accurate reading. A 65-psi discharge pressure from the engine will flow 265 gpm from the 2½-inch handline.

The pump evolution that simulates a high-rise fire protection system.

Take the same 2½-inch handline and connect it to an actual standpipe on a 65-psi residual pressure system and you will find that you can get more water/pressure. Why? Because the system is designed for 65 psi at 500 gpm. The building pump only has one speed or power potential, which is set for the 500-gpm/65-psi flow. Therefore, if you flow less than 500 gpm-which you would do with the 2½-inch handline-the residual pressure will be higher because the pump will not adjust to the lower flow. This residual pressure can increase by 30 psi or more. This is reality.

To prove this theory, we conducted a series of flow tests on an actual 65-psi/500-gpm building system, the Binion Horseshoe Hotel in Las Vegas. We performed several tests with this system to find out how each size handline will perform. The tests included 1¾-inch, 1.88-inch, 2-inch and 2½-inch hose in 150-foot lengths. The test was to see how much water each handline would flow on system pressure only.

 

 

Figure 4: The potential of the high-rise fire protection system is a lot greater than portrayed by the tests commonly done off of engine companies.

Figure 4 shows the results. As you can see, there’s quite a difference in the tests done at the Horseshoe vs. the tests done off of an engine. The bottom line: The potential of the high-rise fire protection system is a lot greater than portrayed by the tests commonly done off of engine companies. The common tests often paint the potential of a high-rise system in a negative light, thus concluding that crews should exclusively use the 2½-inch handline for high-rise firefighting.

Perform Your Own Tests
We were very fortunate to have the Binion Horseshoe Hotel help us with the flow tests. However, having access to a high-rise building for this type of testing is rare; there’s just too many logistics to deal with and possible costs to go with it. But you can conduct your own tests easily and accurately by simulating the high-rise system.

Let’s use the same 65-psi system that was tested at the Binions Horseshoe Hotel. The equipment needed for this test is as follows:

  • One engine company
  • A minimum of 500 gpm for water supply
  • Up to three 10-foot sections of 2½-inch or 3-inch hose.
  • A 2½-inch gated valve
  • A flow meter
  • An in-line 2½-inch pressure gauge.

The pump evolution that simulates a high-rise fire protection system.

Establish a water supply with two of the short sections of 2½-inch or 3-inch hose, keeping the flow meter tube in between them. Flow meters are most accurate when they have straight hose going into the intake side of the tube and exiting on the discharge side. The goal is to flow 500 gpm at the system pressure of choice, in this case 65 psi.

Open the discharge valve that is going to be used to deliver the 500 gpm through one 10 foot section of 2½-inch or 3-inch hose. Connect the 2½-inch in-line gauge and the 2½-inch gate valve to the end of the short section of discharge hose and flow 500 gpm through the line. I used a Tee Diverter to discharge the water because it creates no nozzle reaction due to the 2½-inch opening coming directly out of the hose and exiting both right and left in the diverter.

After getting the 500 gpm, gate down the 2½-inch gate valve to get the required system pressure (in our case 65 psi). You will have to readjust the flow once you start gating down the valve to get the required pressure. Once this is established, keep the engine RPMs and the gate valve at the set position for the 500 gpm flow and shut down the discharge valve itself. When that is accomplished, you can connect the handline of choice and conduct your flow tests. This process can be used to test various hose evolutions encountered in a high-rise structure.

An alternative method for conducting these tests involves setting the flow/pressure by RPMs. In fact, only way method you can use if your engine is equipped with the new electronic governor system.

The same equipment and evolution is used for the RPM method. Once everything is in place, throttle up to gain the flow of 500 gpm and the required simulated standpipe residual pressure. When you achieve this, note the engine RPMs. Next, throttle the engine down and remove whatever device was used to discharge 500 gpm. Connect the handline tha’s going to be evaluated. Remember not to touch the gate valve at the end of the simulated standpipe. It has been gated down to achieve whatever standpipe residual pressure was used. After the handline has been connected, simply throttle up to the predetermined RPM and you’re ready to go. This same method is used for the electronic pressure governor systems. The key here is that the governor system must be set in the RPM mode.

Important: Connect an in-line pressure gauge to the standpipe just before the handline to make sure that the system pressure is adequate. This should be done no matter what size hoseline is to be used. If the fire is at a point where a small handline can achieve a knockdown, test the small handline first. If the numbers are good, then the small handline can be an option.

Connect an in-line pressure gauge to the standpipe just before the handline to make sure that the system pressure is adequate.

What’s Right for You?
I encourage fire departments to do similar tests. Our tests were done with specific makes of hose and nozzles. Your tests should involve the equipment you will use in an actual high-rise incident. Also, consider reaching out to the local fire protection system contractor. They have a good understanding of the local high-rise fire protection systems and the codes that the systems were built to. They can often clear up misunderstandings that we may have that could affect the performance of our operations.

The standard for high-rise operations remains the 2½-inch line, but these tests show that there are cases where smaller lines can be used, and crews can therefore take advantage of their maneuverability. At the end of the day, it’s up to your department to make the decision on what works best for you.

Authored By: Paul Shapiro

Paul Shapiro specializes in the research, development and training of large-flow water-delivery systems and fire stream management. His extensive research in outcomes of large-diameter hose, both as supply and discharge lines, has been published frequently in fire service trade magazines. Shapiro has been involved with the fire service since 1981, and retired after 28 years s an engineer with the City of Las Vegas Fire & Rescue. He is a certified Fire Instructor III for the State of Nevada, has served on the faculty of many fire academies throughout the United States, and was named Instructor of the Year in 1999 by the Colorado Fire Academy. A nationally recognized expert in his field, Shapiro is also the author of the book Layin’ the Big Lines, a book on large-flow water delivery.

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