Last week we discussed NFPA 14 and the design standards and required static and residual pressure parameters for installation. It is important to remember that standpipe systems designed prior to 1993 have a required operating pressure between 65 psi and 100 psi. Standpipe systems designed Post 1993 have a required residual pressure between 100 psi and 175 psi. Outlets are required to produce 250 GPM. REMEMBER, if the standpipe valve is a Pressure Reducing Valve, it does not matter how much pressure the fire department pumper pumps into the system, you WILL NOT get more pressure than the valve is set to give you. Also remember, NFPA 13 specifically recommends the use of 2.5” hose for standpipe operations because of these factors.
Smooth bore nozzles can be operated at nozzle pressures from 40 to 60 psi. Obviously, the less the nozzle pressure, the less the nozzle reaction and GPM. The more the nozzle pressure, the more the nozzle reaction and the more the GPM flowed.
Below are typical nozzle tip sizes with flows at 40, 50, and 60 psi that you may see on different high-rise packs:
15/16" – 165 GPM @ 40 psi, 185 GPM @ 50 psi, 202 GPM @ 60 psi
1" – 188 GPM @ 40 psi, 210 GPM @ 50 psi, 230 GPM @ 60 psi
1 1/16” – 212 GPM @ 40 psi, 237 @ 50 psi, 260 @ 60 psi
1 1/8 " – 238 GPM @ 40 psi, 266 GPM @ 50 psi, 291 GPM @ 60 psi
1 3/16" – 265 GPM @ 40 psi, 296 GPM @ 50 psi, 324 GPM @ 60 psi
1 1/4" – 293 GPM @ 40 psi, 328 GPM @ 50 psi, 359 GPM @ 60 psi
You may find 15/16" tips on 1.75" hose and 2" hose.
The 1" tip is a common tip for 2" hose.
The 1 1/16” tip is a lesser known but great tip for 2” hose. With it, you can achieve near commercial flows if you have enough pressure. If you have enough pressure, you can achieve the flow the 1 1/8” tip.
The 1 1/8 tip can be used on 2" hose or 2.5" hose. If used on 2" hose expect high PDP that will exceed most standpipe capabilities. More often than not, you will find departments that use this set up coming off an engine for their commercial flow.
The 1 3/16" tip has been called "the missing tip". It is relatively new. At a NP of 40 psi it flows 265 psi, the equivalent of a 1 1/8” tip and when over pumped at 60 psi it flows 324 GPM, which is the equivalent of a 1 1/4" nozzle at 50 psi.
Lastly, the the 1 1/4 tip is used by departments across the country. It has a high nozzle reaction and by many is considered too much for a two man nozzle team. Departments with heavy manning, such as Chicago, use this tip.
A couple of words on nozzle reaction. Dennis Legear, (google Legear Engineering Consultants) has stated that the recommended maximum nozzle reaction for 2 people on a line is 115 lbs.
A 1 1/8" nozzle pumped at 50 psi produces a nozzle reaction of 99 lbs. A 1 3/16" nozzle at 50 psi produces 111 lbs.
Hose and nozzle selection is important. The two go hand in hand. When choosing your weapons, you want high-volume, low-pressure systems with acceptable nozzle reaction.
Departments across the country use anything from 1.75” hose to 2.5” hose for their standpipe operations. It is important to spec your hose and nozzle package for your jurisdiction. If all of your mid rise and high rise buildings were built post 1993 then 2” hose may be a very acceptable choice for you.
If your jurisdiction has mostly buildings built prior to 1993, then you should be strongly considering the use of 2.5” hose because of the 65 psi to 100 psi range.
Another thing to think of when choosing hose size is the type of occupancy your buildings are. If all your high rise buildings are hotels or apartment type buildings that are compartmentalized then lower flows such as the 210 or 240 GPM range may be acceptable to you.
If you have commercial, open floor plans that present the opportunity for rapid fire growth, then you will want to consider higher flows that come for the 1 1/8” and 1 3/16” tip.
It is extremely important to remember the staffing levels should not decide what size hose you buy and use. The fire decides what size hose you should be using.
My department has long used 1.75” for standpipe operations. Up until a few months ago, we did not even have 2.5” hose at the department. Now, some of our newer engines are running pre-connected 2.5” with play pipe style nozzles. Before this we used 3” hose strictly as defensive exterior hose lines.
When the last hose order was placed, we purchased 2” hose with 2.5” couplings as well as new “offensive” nozzles for this hose. We have 8 companies with this new set up. Most of our buildings are Pre 1993 NFPA 14, including the Top Ten Tallest Buildings in the city which are a mix of commercial and residential.
Because of this, for our jurisdiction, I’m an outspoken proponent of 2.5” hose. However, as stated above, we will have a mix of 2” hose with 1” tips, and 1.75” hose with 15/16” tips anytime we get a high rise fire.
Below I’ll break down FL for a few different hose sizes at different lengths so that you can see where certain packages are not acceptable for Pre 1993 NFPA 14 systems.
1.75" hose with a 15/16" tip flows 185 gpm.
- 150 ft lay - 80 psi FL + 50 psi NP + 5 psi elevation = 135 psi
- 200 ft lay - 106 psi FL + 50 psi NP + 5 psi elevation = 161 psi
- 250 ft lay - 133 psi FL + 50 psi NP + 5 psi elevation = 188 psi
2" hose with 2.5" couplings with a 1" tip flows 210 gpm
- 150 ft lay - 37 psi FL + 50 psi NP + 5 psi elevation = 92 psi
- 200 ft lay - 49 psi FL + 50 psi NP + 5 psi elevation = 104 psi
- 250 ft lay - 62 psi FL + 50 psi NP + 5 psi elevation = 117 psi
2.5" hose with a 1 1/8" tip flows 265 gpm
- 150 ft lay - 21 psi FL + 50 psi NP + 5 psi elevation = 76 psi
- 200 ft lay - 28 psi FL + 50 psi NP + 5 psi elevation = 83 psi
- 250 ft lay - 35 psi FL + 50 psi NP + 5 psi elevation = 90 psi
All of these FL figures are text book except for the 2” hose. The 2” hose FL numbers are for our Firequip 2” hose at my department. As always, know your hose. When purchasing hose, have the hose manufacture flow test hose for you so you can see the actual flows. There are 1.75” with half the text book FL. Also, some 2.5” hose may be closer to 3” and have less FL.
Look back across the FL numbers above. The 2.5” hose is the only hose that has all operating pressures between the minimum and the maximum allowed pressures in a Pre 1993 standpipe system and the lowest required pressure is still 10 more psi than the minimum allowed pressure of a pre 1993 system.
Remember for standpipe operations, we want a high-volume, low pressure weapon. We want commercial flow capabilities even on residential high rises. A couple of reasons are due to the possibility of wind driven fires and due to "reflex time". Reflex time is the time from when you arrive on scene to the time water goes on the fire. What might be a small kitchen fire when you arrive could very well be pushing down a hallway by the time you are hooked up and ready to fight the fire. The average reflex time for high-rise fires is around 15 minutes. Remember, fire doubles in size every minute.
Set yourself up for success by putting a 2.5" hose in service to start with. You will be covered for fire flow and for low pressures that may be found in standpipe systems.