Fire Department Hose Loss vs. Standpipe?

6/26/2020

I’m a Fire Inspector/Design Reviewer and I have a problem that I’ve been trying to tackle. NFPA 14 systems are designed for high volume low pressure firefighting tactics, but the majority of fire departments in America use high pressure low volume equipment. Here are the key points:

NFPA 14 Type 1 standpipe systems provide 250 gpm at 100 psi with 200 ft to most remote location in a sprinkled building. In the firefighting world this equates to a fire attack with 250 ft of 2.5” hose and a 1-1/8” smooth bore nozzle. The 250 ft comes from, 50 ft to stretch to the hose connection on the floor below the fire floor and 200 ft to most remote location on the fire floor. Fire ground friction loss calculations for 250 gpm through 2.5” hose is 15 psi loss per 100 ft. A smooth bore nozzle requires 50 psi to operate properly. We are stretching from the floor below so we have roughly 6 psi head loss. So the required pressure at the hose valve is 93.5 psi. You can see that the NFPA 14 design requirements are in line with the use of this higher volume lower pressure equipment.

The problem is that 2.5” hose is very heavy and requires a lot of man power. 2.5” attach lines are used by large city departments like Seattle, New York, and Chicago. Many smaller city and town departments don’t have the staffing to stretch such big lines. We may only have a couple firefighters stretching an attack line where as the big cities would have 6 or more. So we use smaller more maneuverable hose and more pressure demanding fog nozzles.

A more typical firefighting set up in the majority of fire departments would be 1.75” or 2” hose and a 75 psi or 100 psi fog nozzle flowing between 150-200 gpm. I’ll use Bozeman as an example. We use 1.75” hose, a 75 psi fog nozzle, and a target flow of 175 gpm. In our experience the pressure loss per 100-ft of 1.75” hose with 175 gpm is 50 psi. So if we need to stretch 250 ft of hose, we would need 206 psi at the hose valve on the landing below the fire floor. Add in that the tallest building we have is 11 stories, and a 25 psi pressure loss adjustment for pumping the FDC, and we are up to 285 psi required at the FDC.

There seems to be a disconnect between the design world and the firefighting world. This poses all sorts of problems such as compromising sprinkler systems and old standpipe systems since they may have components that are not rated for such high pressures. Even worse are systems with pressure reducing hose valves that wouldn’t even allow us to pump the FDC to get anywhere near the pressures we need with our equipment (see One Meridian Plaza fire in Philadelphia).

I think that Fire Departments need to communicate their design needs to designers, and Fire Departments also need to look at the equipment they use, and see how they can make changes to operate more closely to what NFPA 14 systems are designed for.

If you have any knowledge on this topic I would love to hear it, thanks in advance.

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11 Comments

Dan Wilder

6/26/2020 08:26:26 am

This sounds more like the need for the NFPA 14 Committees to have Public Inputs pushed to them to account for these types of requirements OR having your local Building/Fire Codes amended accordingly.

I would suggest reaching out to your local AFSA/NFSA representatives and see if they can provide support through Committees like the NFSA Engineering & Standards or AFSA's equivalent. I would also push for you to reach out to the Technical Committee for NFPA 14 (They are listed at the beginning of that standard) to see what options are available. it would also be helpful to see how many departments this affects.

If your AHJ can make the amendments at the jurisdictional level then you already have a leg up on the implementation. Changing the FD equipment, as your stated, can also resolve the issue but then this becomes a budget issue and probably the worst of the 3 options to proceed with due to the all at once implementation.

I would be interested to find out why something this specific, that would potentially affect a greater number or departments, hasn't been pushed further. Any failures that could be documented to support the position as well.

Jonathan Joseph

6/26/2020 10:25:09 am

In California we have a California Fire Code and are hose pull is greatly decreased. Fire departments use 2 1/2 in hoses that 100ft and with the 250 gpm and 100 psi the nozzles spray 30ft. minimum
A remote area of a sprinklered building can not be more than 150 feet from the hose connection if it does exceed 150 feet an additional hose valve shall be installed.

I would definitely address this to your local authorities as well as your State Fire Marshal because there has to be some compromise. Always remember that the NFPA Standards are a minimum standards of installation and design.

Hope that helps

David Hartrman

6/27/2020 10:05:16 pm

Thank you. Reducing distance from hose valve to most remote areas in sprinkled buildings from 200 ft to 150 ft would definitely make a difference.

Brian Gerdwagen FPE

6/26/2020 10:32:46 am

This requirement is to provide the fire department with something before the truck shows up and boosts the pressure. There is also no way that the fittings installed will handle 285 psi at the FDC. You can make an 11 story building work without a PRV. It will be close, but the usual break point is 12 stories. You may begin to have the 175# rated fittings fail if you have an older building.

If we want to stop installing automatic or manual wet-standpipes and revert to manual dry with 300# fittings, that is great. It would eliminate a lot of the design headaches and fire pumps from buildings that do not need them for sprinklers, only the standpipe demand.

I have always thought combining the hose connections and sprinklers has been a bad decision. You can not control how much you are over-discharging the sprinklers when you increase the pressure for the hose lines.

Glenn Berger

6/26/2020 10:33:31 am

The local Fire Department requirement needs to be clear to the Design and/or Construct working in that municipality. I have seen this done as City Amendments to the State and National Building and Fire Codes. Also each system designer should have a meeting with their corresponding city official to understand local conditions.

Rob Bambino

6/26/2020 10:39:52 am

250' of hose for an interior attack is a bit much. Generally, 150' is the reach of the hose, and that is why we would require intermediate hose connections on the floor if the hose stretch exceeds the 150 from the stairwell. With that in mind, at 150' of 1 3/4 hose with a adjustable nozzle would be much less than your 285 figure, and generally at 100' for 1 3/4 its a 30psi loss.

David

6/27/2020 10:02:10 pm

Thank you very much for your input on this. I agree that a 250 ft stretch is a tall order and a worst case scenario.

I believe NPFA 14 allows for 200 ft from hose valves on a floor to the most remote location in a sprinkler protected buildings and 150 ft for unsprinkled. I added an additional 50 ft for the practice of connecting to the hose valve on the landing below the fire floor.

My understanding is that there is 30 psi loss per 100 ft of 1.75” when flowing 150 gpm. My figures are based on 175 gpm. I do understand that this is asking a lot for 1.75” hose, and that 150 gpm is more the industry standard. I’m using my departments standard practice in my example.

I like the idea of requiring more hose valves when stretches greater than 150 ft exist. Do you require that they be in a protected stairwell?

If we flow 150 gpm instead of 175, use smooth bore nozzles, and reduce hose stretches to 150 ft, we would be able to get our required pressures down to something closer to 100 psi at the valve connection. Thank you.

Fred

6/29/2020 07:31:44 am

Fire Departments should not be using higher pressure fog nozzles on their high rise packs for many of the reasons you mentioned. Higher pressure such as 100 psi at the tip vs 50 psi on a smooth bore. Their have been LODD due to this type of setup over the years and it is not advised and frowned upon in the fire service today. Besides pressure another issue is debris in the system can clog and restrict water flow in fog nozzle where the smooth bore will pass most debris. Some departments that use 1.75" as high rise hose need to understand the flows in buildings in their jurisdiction, so maybe it works for them, but at least use a smooth bore for a lower operating pressure and debris possibility. Some departments are switching to 2" hose with 2.5" couplings for lower operating pressures and higher flow, as typical 2" hose has only 1.5" couplings.

Firefighters like the shortest possible hose stretch and will pick the stairwell closest to the fire. Firefighters prefer not to hook up to hose outlets in corridors as conditions in a fire can change rapidly and prefer that the hose line leads to a safe location out such as a fire rated stairwell, not in the middle of a corridor. I never understood the reasoning for these corridor hose outlets or some buildings that had such long hose stretches until I got into the codes. I would never hook up to a corridor outlet unless fire was knocked down and contained from a sprinkler activation. Buildings with no sprinklers, we would always stretch from a stairwell. Just figured I would give a retired fire suppression guy perspective that is now into the code side of things, trying to learn from all of your awesome posts! I have learned so much reading here and Joe's awesome site.

Bruce Verhei link

6/29/2020 06:58:45 pm

1. Hooking up the on floor below. This is a historical practice rooted in the open stairwells of the past. I find it unlikely you are operating in tenement-like conditions. You are in a rated stairwell, inspected by a stalwart building inspector, with maintenance inspection by a steely eyed fire inspector. There is a least one rated door between you and the fire. The fire inspector ensured even the smoke seal is in place. Hook up on the fire floor. Save 50’ of hose. Advance your FD into the ‘80’s.

2. There are now 50 psi fog nozzles available. Appropriate sized solid tips also available for 1 3/4 or 2” lines. You may find some larger departments are using 2” coupled 1 1/2” lines. You may want to investigate friction loss in latest hose. Friction loss continues to drop in modern hose.

3. Debris. Time to convert to Knox or similar caps and plugs. Combine this with an actual, not theoretical, ITM program. Eliminate the problem at the source.

Does your department have an inventory of all fire protection systems needing periodic ITM, and a real FPS program? Example: If a third party inspection and testing of that standpipe is due in July 2020 do you send a reminder postcard in June? Do you have a way to run a report by the 10th of August and confirm you’ve received ITM reports for every system due in July.

I should be able to look at the standpipe or kitchen H&D or FACU and confirm it is on your city’s inventory.

If not you have a bigger problem with that standpipe than design pressures. I mean this to all Fire rep’s reading this, not you in particular.

4. Fred, intermediate standpipe outlets. There was a failure to understand that exit distances and standpipe hose bundles lengths were associated when exiting chapters of the ‘97 UBC & UFC were totally rewritten by a consultant hired by a multinational aerospace firm. The exiting chapters of the IBC and IFC were largely derived the ‘97 Uniform codes.

Not surprisingly Boeing’s consultant proposed longer exit travel distances in almost all non-H occupancies.

Common exit distances used to be 150’ not sprinklered, 200’ sprinklered. Now most code minimum standard exit distances in multistory buildings are 200’, and 250’ respectively.

Adding intermediate outlets at a later date was a fix, and not a great one.

5. Paul Grimwood, Kent Fire and Life Safety, Kent England, has convinced me that the basic layout of outlets is poor practice. As a best practice he advocates a FF’s lobby off the stairwell. Standpipe outlets and the elevator intended for FF’s use during fire are at this lobby. Use of outlets in lobby does not allow smoke to contaminate the stairwell, as attack lines don’t prop stairwell door partially open.

As second best he advocates provision of the metric equivalent of 2 x 2 1/2” outlets 36” onto the floor past the stairwell door. Again, the stairwell door opens and closes as FF’s pass through, but doesn’t stay open. Stairwell pressurization functions as designed.

Two outlets are necessary to put two attack lines in service. In large office areas this may be necessary to put adequate fire flow in play. In residential corridors this allows backup line to protect attack line crew, especially if a window blows out on windward side of building.

I would following Paul Grimwood if you don’t do so already.

Best.

Bruce Verhei

Jessica L.

7/1/2020 10:52:00 am

Thank you all so much for sharing this conversation!

Chris Baker

4/22/2024 11:35:51 am

Do we really need that extra 25psi for pumping the FDC if we aren't flowing upwards of 1400lpm/370ish US Gal, though?

Fire Department Hose Loss vs. Standpipe?

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