Folks,I have just went through the 2006 thread with regards to Standpipes and Multiple FDC's etc. However I still have a couple of long winded questions. I apologize in advance.

When designing a combined system (standpipe/sprinkler system)the hydraulic calcs. includes calculating 500 gpm @ 100 psi for the most remote standpipe, and 250 gpm for each additional standpipe up to a max. 1,000 gpm. If the bldg. is partially sprinklered then up to max 1,250 gpm. If the building is completely sprinklered then you do not add the flow of the sprinkler system to the standpipe calculation.

NFPA 14-(5.2.5) Talks about a Manual Wet Standpipe System connected to a water supply that can maintain the water in the system but cannot deliver the system demand to the standpipe. The system demand is left for when the pumper truck arrives on-site.

So to my question. Do you then just base your hydraulic piping sizing on the most demanding sprinkler area: 1500 ft2 @ 0.1 gpm/ft2 + the combined hose allowance = approx. 250 gpm.

If so what size is the riser pipes for when the pumper truck arrives on site? Does the pumper truck have pretty much unlimited flow and pressure? Can they provide 1,000 gpm @ 100 psi at the top of a 4 story building? Typically what are the size of these pumper trucks pump?

Basically when sizing the riser for the Combined System do you just ignore the 500 gpm @ 100 psi at most remote standpipe if your considering it a manual standpipe? Why wouldn't you always call it a manual standpipe, seems it would save a lot of dollars? Does this need to be accepted from the AHJ?

Getting on to the multiple FDC's? I see from the 2006 thread, that most AHJ want a max. of 1 FDC and if there are multiples they want them interconnected inside of the building. My boss is questioning me (since I'm the most familiar with sprinkler in our HVAC firm, scary I know) on him seeing buildings with 4 FDC's on the side of the building. Each with their own sign: "EAST STANDPIPE" "WEST STANDPIPE" "NORTH STANDPIPE" and one final FDC for "SRPINKLERS". Does anyone know if this was an old requirement for each stairwell to having it's own FDC. Or if we went inside of these buildings would they all be interconnected. Which would be stupid then why would you ever install more then just one. Even if you had a building over 52,000ft2 foot print with 2 alarm valves would you even need more then 1 FDC? Where would you ever need more then 1 FDC? Never ever Ever?

And one final rant before signing off. I'm working out of Canada and our National Building Code feels the need to throw in their 2 cents worth. NBC 2005-3.2.5.9 States the following " If more then one standpipe is provided, the total water supply need not be more then 30 L/s (475 gpm)." And pretty much refer to the NFPA 14 right after, why wouldn't they just say for buildings 4 stories or higher, standpipes are required see NFPA 14.

As well NBC 2005 3.2.5.9. 6) "A fire department connection shall be provided for every standpipe?" LIKE WTF?

Anyway if anyone actually makes it through the whole rant and feels like replying to one or all questions, it is very much appreciated!!

Virtually all standpipe systems will need some type of pump. The exception is if you have very high city water pressures as seen in some areas of the country.

You can have manual or automatic standpipe systems. A manula standpipe is to be used when the building is between 30' - 75'. Once you break 75', you must have an automatic standpipe. A manual standpipe system will have a fire pump. It is the one that comes on the pumper truck

from the fire dept. You still need to calculate your standpipe system just like any other. Check with your local FD, but it is likely that the Fire Dept will be able to provide a minimum of 150 psi @ 1000 gpm at the inlet of the FDC. Therefore, you calculate the standpipe as you stated, but the supply is the fire dept connection.

For combined systems, you will have separate calculations. You will calculate the standpipe system to size the bulk mains and standpipes. You will then need to calculate the fire sprinkler system utilizing the city supply. I have seen several small 4-6 story office buildings where a 4" fire line is brought into the building, with a 4" backflow preventer, but is upsized to 6" at the FDC because the standpipes req'd 6" bulk pipe based on the calculations. We have also had jobs where a 300 gpm pump was installed to supply the sprinkler system. The standpipe demand was 1000 gpm, but that is satisfied through the fire dept connection.

As far as multiple FDC connections, I have frequently seen that with manual dry standpipes. Just run the standpipe up the stairwell and put an FDC at that stairwell. I have also seen more AHJs ask for a second FDC on larger projects. It is just to have a second line of supply to the standpipe system if the primary FDC is not usable for some reason.

I hope this makes sense. Have a good weekend.Per 2010 NFPA 14, 7.10.1.2.2 I'm providing 250 Hose allowance at all three (3) 2-1/2" Hose Connections of a Class 1 Standpipe System. per 7.8.1, I'm providing 100psi at the most hydraulically remote single 2-1/2" connection.The System is Manual and Combined with two separate Wet pipe Sprinkler Systems.Let me try and guess the answer to the unstated question., If it's manual wet combined system then pumper truck provides the 750@ 100 psig reqd by NFPA 14,

The water supply has to support that flow from an exterior hydrant without dropping below 20 psig on any portion of the underground piping (adjusted for elevation).

The water supply has to supply the worst case sprinkler demand, plus the required exterior hose stream.But it does not have to supply both the standpipe demand (nfpa14) and sprinkler demand (NFPA 13) at the same time. Sorry...fairly new at this.My Question is, Is it the intent of 7.8.1 to require 100PSI at all outlets simultaneously, or just the one most remote..? You already answered it in your first post. Pressure at the hydraulically most remote outlet can't drop below 100 psi while flowing your total demand.

Logic would dictate that if you can provide at least 100 psi at the most remote, you are providing more than that at the less remote outlets. Yes...this is where it gets a bit tricky. The Stdp System is a Horz. type and is Combined with 2 Wet Pipe Sprinklers. Of the three Hose Valves, One Connection comes off one of the Wet Sprinkler Sys and Two Connections come off the other. They Share the FDC. All three valves are at the same elevation, which is 30" AFF. Does it matter where the Hose Connections are in relation to one another? Seperate Fire area, Building Etc? The Fire Department is only allowing 150 PSI from their Truck, and the most remote Connection is 1200 ft away. I can Prove that each has valve can deliver 100/250 w/ 250 flowing as allowance at each of the other connections, but not 100/250 at all simultaneously. Hmm. If the hose connections "comes off the sprinkler sys", as in connects downstream of the sprinkler system riser, that is NOT an NFPA 14 standpipe system.. My opinion that is NFPA 13 system that has interior hose connections..

No wonder the calcs are not working, you are having to push that water though all the sprinkler system components.

These used to be used for storage, for workers to use to 'fight the fire', until it was finally admitted they did more harm than good by delaying the FD response.

I sketch scanned and added as an attachment would greatly benefit you at this point. People would be able to help point you in the right direction and get a full understanding of the situation.

It is a Class 1 Combined per NFPA 14 in a County Jail w/ an I-3 occupancy and the local FM's interpretation of 905.3.9 of the (Ca) CFC 2007 for a "Class 1 Standpipe System ...provided in all areas where 50 or more inmates are restrained". Given this, three Separate Detention Pods meet this criteria and so three single 2-1/2" hose connections are being provided, one at each of the Pods exterior sallyports. You may need to increase your pipe sizes in your A1-A2-C1-A1 loop. It doesn't matter that your particular installation has 1200' from the FDC, per NFPA 14, you are required to provide 100 psi at all outlets as a minimum. If you calc through the hoses and such, you may be able to include your city pressure. After all, the fire truck is just a "portable booster pump." Do you also have a problem of going above 175 psi on the sprinkler piping?????

If say your main pressure is 80psi. And you add 120 psi from the brt you will be at 200 Taken literally, NFPA 14 7.8.1 and 7.8.1.1 clearly states "100psi at most remote or top most outlet." Not all. I understand that in a vertical standpipe due to elevation, 100psi is implied as available at all connections, but at "any and all connections" and at the same time? I just have a hard time thinking that that's the intent.Seems to me that the Water Allowance of 500/250 for additional standpipes/connections is more of the objective. From a Fire Fighting Standpoint, I would agree that if you had 2 or 3 standpipes and/or hose connections in the same area.. like a roof top or open Mall Structure, the 100PSI at each at the same time makes sense. But in a "horizontal" arrangement with connections in completely separated fire areas, with no common means of access to one another...? Cdafd, Tried to convince the FD that the 100 psi static city pressure in addition to their 2500GPM booster pump (Hale Qmax)on thier 300Hp Engine should be more then sufficient to meet anything they wanted. Unfortunately and for some unknown reason, the FM is only allowing us 150PSI at the FDC, in a flat curve @ 750GPM. FYI...and although not shown on the Flow Diagram, All pipe is 6" and 4". 6" feeding 3 connections, 4" feeding everything else. I think everyone on here has stated that you need 100 psi at each outlet flowing simultaneously. If you can prove that the FD will not be able to use 2 or 3 hose valves at the same time to fight a fire, submit the plan as you want it and see if it gets approved. Then make sure you have insurance paid up just in case something goes wrong during a fire event. I think a good lawyer would eat you up on your detail there, but I am not an attorney, so I don't know for sure. I always tend to err on the side of being conservative if I find what I feel is a grey area. Only you can make the call on this and see how it plays out.

Good luck on it. Let us know what gets approved by all agencies involved. I find it pretty interesting how some of these things end up turning out.

The fd is probably saying they have a 750 gpm pump

They will crank it to maybe max 150 psi

That does not take into account the city main pressure added to it

Not a FPE but if you calculate a remote area I take it is assumed the rest of the heads have the same needed pressure

Same as the other posts if you hit 100 psi at the remote you should have at least 100 at all connections before it

Fd sometimes depending on nozzle used , it needs around 100 psi for it to work correctly The minimum requirement of NFPA 14 for a single standpipe riser shall be 500 gpm at a minimum residual pressure of 100 psi (maximum of 175 psi), so if you have 2 riser it should be at 750 gpm capacity and again the remotest shall be 100 psi minimum. If you calculate this set the "remotest" at 100 psi and you will found out that the pressure required from the other 2 1/2 in hose connection would be lesser compared to the remtoest Hose Connection.

If a low rise building can be allowed to have a manual standpipe, i.e. calc it with supply by fdc only, but sprinkler system needs a firepump, could you size the pump just for sprinkler demand? This would be a difference between a 200 gpm pump for sprinkler or 1000 gpm pump for 3 standpipes. In other words, if there was no firepump it would be ok with fdc, but if we add a firepump does the standpipe requirements somehow kick in so that it has to be supplied with same min psi and gpm through the automatic supply. It would be combination class 1 standpipes. Thanks for any help. I have done several as you mention. We calculate the standpipe system and size the piping based on using the FDC. You need to realize that a manual wet standpipe has a fire pump, it is just located on the responding fire truck.

We then size the fire sprinkler system and pump based on the fire sprinkler demand. It is not uncommon to see a 300-500 gpm pump used in a building like this.

Most of these I have done, we have a 6" FDC and 6" bulk to the split in the standpipe bulk to go up each stair. We also bring in a 6" underground and use a 6" bypass. The fire pump and all valves are sized per NFPA 20. It greatly reduces the costs of installation. So much depends on where you are located. IMO of all the standards NFPA #14 is the one most fiddled with by AHJ's.

Howard County, Maryland for example.

Standpipe Policy: May 24, 2001Memo to: Sprinkler System Designers / InstallersFrom:Donald L. Mock, Fire Protection EngineerSubject: Standpipe Design Criteria

The International Building Code requires standpipe systems to be installed in accordance with NFPA 14. Howard County has adopted by reference the 2000 edition of NFPA 14. Section 5-7 requires a minimum residual pressure of 100 psi at the most remote hose connection. The authority having jurisdiction can allow the residual pressure to be reduced to 65 psi at the most remote hose connection. We will allow standpipe systems to be designed to a minimum residual pressure of 65 psi at the most remote hose connection.

Howard County will also allow the following exception to the minimum residual pressure of 65 psi at the top most hose connection in fully sprinkled buildings when the building does not otherwise require a fire pump to meet the minimum sprinkler system design pressure.

The residual pressure of 65 psi is not required in fully sprinkled buildings where the highest floor level is not more than 75 feet above the lowest level of Fire Department vehicle access. The riser shall be sized so that the Fire Department can supply the minimum 65 psi at the most remote hose connection, based upon an FDC input pressure of 150 psi.

---------------------IMO I like what Howard County did. I could live with that.

Here in Georgia for all buildings you must meet the 100 psi, 65 psi if local AHJ agrees, except in buildings, other than a high rise, where all standpipe piping is 8" in diameter then you don't have to design to anything. When they made everything 8" Georgia did away with allowing manual

standpipes but, before this passed, I did a number as you and Travis suggested.

In my view you need to ask the local AHJ some specific questions.... doubt you will find your answer here.

Best of luck.

q1-i am designing a light hazard building with partial sprinkler protection and using cabinets for the rest of building so it's a combined system the flow rate for the sprinkler is about 200 gpm .what should be the system flow rate .i understand from nfpa 14 that it will be 250 gpm for cabinets plus 150 gpm for sprinkler am i right??i am using one main riser what should the diameter be?q-2 if i am designing a fully sprinklered system what should i do with the hose allowance ?should i put cabinets according to nfpa 14 ?will it be a combined system??

NFPA 13 and NFPA 14 are two different things. You have the fire sprinkler demand and separately you have the standpipe demand.

If I understand your question you have a partially sprinklered building so you need to add the sprinkler demand to the standpipe per 7.10.1.3.2I think, reading the code, you would add the 150gpm instead of the 200gpm.

If your building is fully sprinklered you can calculate the standpipes with the normal demand. I put the hose stream for fire sprinkler systems at the nearest hydrant or the connection to the water main.

What are the requirements for design flow for a combined system standpipe?

Let's say I am designing for NFPA 13 Ordinary 2, I read that the inside hose would be 100 gpm and outside would be 150 gpm (total 250 gpm inside/outside).. But the purpose of a 100 gpm hose (1-1/2") would be for first-aid fire fighting and clean up, not fighting a fire..

Then NFPA 14 requires four 2-1/2" hoses (1000 gpm total), but without any sprinklers flowing.

So does NFPA 13 or NFPA 14 not address the situation of design sprinklers flowing at the same time as 2-1/2" attack hoses?

I don't understand the logic of designing either fora) sprinklers + a clean-up hose, orb) four 2-1/2" attack hoses, but no sprinklers operating..

Am I just imagining that firefighers would want to leave the sprinklers operating and still hook-up to hoses? If so, the system would not be designed to accomodate both the hoses and a design fire area.

If anyone can shed some light, I would appreciate it!

(OP)1 Dec 09 23:22

firepe, there is a "qualified" fpe.. But a title means nothing to me, so I check their work before it goes to bid. Numerous code errors.

Right now the answers I have are "that's just the way it is". Or "they will boost the flow and pressure with an engine". It may also have something to do with statistics, and that very few fires grow past a few heads, so there would be flow available for an attack hose.

Either way, the NFPA 13 and 24 flow requirements are not additive.

ok, I'll bite..

If it's wrong and there are code errors then they're not qualified, are they?

As for NFPA 13 and 14 (not 24), and flow requirements...These are 2 separate and distinct standards, and are not intended to be intermixed. You simply either have a sprinkler system design demand including a hose stream allowance (which should be further divided into inside and outside hose), or you have a standpipe system with a specified flow requirement, which does NOT have to be simultaneously available with the sprinkler demand.

I think you need to look at it as sprinklers first, standpipes after. the standpipes are there for the FD to use, that's all, to assist the application of additional fire water when they arrive (if needed).

Now to really confuse things, let's use the standpipe system to feed the sprinkler system, that ought to stir things up.

But it does not have to. Keep it simple, 2 different standards, DO NOT MIX THEM. firepe,

I understand the 13 and 24 codes are not additive, not mixed, separate codes, etc. all that.. That was clear from the beginning.

The code jockey answer is take the highest of either 13 or 24 requirements. In my example, NFPA 24 would govern for the water supply design and requires 1000 gpm @ 100 psig.

My question was about a realistic scenario, not wording of the code. With a combined system standpipe (sprinklers fed by the same pipe as the attack hoses) why do the codes not allow for leaving the sprinklers on while the fire department is flowing simultaneous through attack hoses?

In other words what is the logic behind designing for either sprinklers or hoses when clearly both may/could be used at the same time.

I've explained some reasoning behind this. The idea is that the pumper truck will take the gpm allotted for outside hose stream and deliver this through the standpipe to the attack hoses. All this would be in parallel with the water coming from the fire pump feeding the sprinklers.. The hangup I have with that is the standpipe will be designed for ~1/2 the flow that would be needed in that situation. So the pressure drop would be alot greater and the fire fighters might need to shutoff the sprinkler flow to get enough flow/pressure for attack hose(s).

You've not furthered the discussion other than to a) question my abilities, and b) prove that you can read a code book and emphasize that I should not be thinking. just put my brain on a shelf, keep it simple, and read the code..

I meant to say NFPA 14 (standpipes), not 24 (private service fire mains).

correct me if I'm wrong here, but you asked an initial question that appeared to indicate some confusion on the application of two related standards, NFPA 13 and NFPA 14.

At that time I suggested you may want to find a "qualified" fpe to help you.

You reponded by stating that there already was a "qualified" fpe, and that "a title means nothing to me, so I check their work before it goes to bid. Numerous code errors."

So pardon me for thinking that you did not trust your "qualified" fpe's information and were back checking, and on a fishing expedition.

As for "furthering the discussion", well, again, I never questioned your abilities, I was simply trying to help you focus on the 2 standards as separate standards. Since you claim you understand this concept, yet still have questions about a "realistic scenario", does make me now wonder.

The standpipes are there to simply provide the fire department a convenient means to deliver fire fighting water for hose streams/mop up operations.

When designing combination systems, it is typical that the sprinkler system demand including the NFPA 13 hose allowance is NOT the most demanding system, the standpipe system IS, so there is an over design, a cushion if you will.

As an example, let's say you have a light hazard sprinkler system with a theoretical water demand of 150-gpm (.10/1500) and a hose alowance of 100-gpm, for a total of 250-gpm. A building with even just 1 standpipe would have a standpipe system design/demand of 500-gpm, which exceeds the sprinkler system demand by 250-gpm (not to mention the 100-gpm allowance in the sprinkler demand).

If you had a building with multiple standpipes and had a system "maxed" ou at a 1000-gpm standpipe system demand, there would be at least 750-gpm left over for the hose streams, in addition to the sprinklers.

So the point is that there already is some overlap built into the designs of these systems within the 2 standards. The fire department will have enough water to apply their hose streams from a properly designed standpipe system, and still leave the sprinklers in service, or they may decide to shut the sprinklers off. either way, this is already unstated, yet built into the standpipe system stadard's design criteria.

Your example is for NFPA 13 light hazard. This particular design exceeds NFPA requirements (highly protected risk), for 0.2 @ 3000. By the time one accounts for pressure overage (~30% in this case), the sprinkler and standpipe demands are roughly equal.

Sprinkler Demand: 0.2@3000 = 600 gpm x 1.3 overage = 780 gpm. Standpipe req't for two standpipes = 750 gpm

So there is no "overlap", no "cushion, if you will" to allow for even ONE hose.. There is nothing "already unstated, yet built into the standpipe system stadard's design criteria" for the higher hazards.

Since you claim you understand this concept, yet still can't understand my point, that does make me now wonder.

Pipenpums, yep, if I was in your shoes, I´ll appreciate the thoughts of experts if you are thinking of the 1350gpm(780+750) demand.

I´ve come across with similar situations but for industrial installations where the cost does not change much among the different hose demand scenario alternatives.

True, an expert designer is required and there is no room for amateurs for such a decision. But I agree with pipesnpumps. I´ve asked similar question to NFPA people and never got a decent response on what the NFPA really wants with respect to combined systems.

I reckon that NFPA 13 intention, according to NFPA101, is to state that sprinklers are enough, and that is useful to sell the idea that sprinklers are not expensive, this if when we are dealing, with a "flat line" of hose demand on the design curve (with no pressure requirement for this hose demand or no big diameters or big pump for other design scenarios).

But with combined systems, the design deals with lots of issues for the designer such as hose demand, pressure reducing devices, interconnection of risers rules, bigger diameter and pumps, etc. that leave place to bad interpretations sometimes.

I think that NFPA 13 or 14 should clarify more or give an appendix with guidelines for combined system, to avoid misunderstandings or bad interpretations.

So going back to the point, I hope more experts can give us their thoughts about combined systems. Personally in every combined system I've designed the standpipe is the most demanding by far in comparison to a sprinkler system.

Given a Class I standpipe and an extra hazard I occupancy the sprinkler piping should be sized according to hydraulic calculations, even though that sounds strange to have an extra hazard I in a combined system. One thing to remember is the standpipe also has the 100 PSI requirement (at the top for Class I) this has in every case pushed the standpipe demand well above that of sprinklers in my experience. I'm certainly no expert but seems to me the confusion comes up with having two separate systems joined with the word "combined".

You're trying to read to much into it.

With few exceptions standpipes and sprinklers have little to do with each other.

The most common exception is reducing standpipe demand to 1,250 gpm in a fully sprinklered building or perhaps a reduction in the required pressure at the top outlet if the building is equipped throughout with sprinklers.

Two completely unrelated hydraulic calculation sets are required. One for just the standpipe the other just for sprinkler as if the standpipe didn't exist. Hose stream for sprinkler would be 100 or 250 which I suppose could be added at the nearest fire hydrant or city connection. I've always been a little unclear about exactly where to add sprinkler hose stream so I always added it at the standpipe. If the standpipe is capable of deslivering 500 gpm to the two top outlets it should be able to easily handle sprinkler plus 100 gpm (most standpipes are in buildings of light hazard) at the nearest hose outlet.