Must calculation be done by manufacturer/contractor?

[cornemo]

I'm currently in a discussion with a terminal owner who has been told that the (flow) calculations for the fire fighting and foam systems have to be done by the manufacturer/supplier(like Tyco). He says that calculations made by an independent engineering company are not valid unless they are approved by the manufacturer/supplier of the system.

I can't find any reference in NFPA for the above statement. If I check for example NFPA 11, chapter 4, 4-4.2 for example it says that "Complete plans.......shall be submitted by the engineer or contractor...." Which in my opinion allows an independent engineering company to do the calculations.

Is there any reference in one of the many NFPA codes which adresses the issue of who can/must make the calculations for the system? Or does someone have experience with this issue?

Thanks in advance for your replies.

With regards, Corné

 

[rbulsara]

Although I am electrical, here are my two cents:
Eventually it depends how the specs are written and responsibility are allocated. Even then, if the system is sold as a "pre-engineered" system by the mfr. they should provide the calcs. If mfr. uses a proprietary software to size pipe sizes, lengths, bends and validate flow, they need to stand by that. Usually those software need to have FM approval or UL listing (if in the USA).

Also if the contractor determines field layout of the piping, he needs to back that up. Although all calcs may need to be approved by a PE familiar with the design, independent or not, it should not matter.

Rafiq Bulsara

http://www.srengineersct.com

 

[sprinkler1000]

In water based systems, if there is a consulting firm doing the project, then it is in its scope to do calculations.
The specs sometimes ask the contracting firm to revise if there are significant changes in the final layout.

If the owner hires the contracting firm and the contracting firm does the design, then is up to it.

I dont have experience with foam or other systems but sometimes (in water mist or inert gas,if I am not wrong) the NFPA gives only guidelines and the manufacturer is the one that makes the calculations and pipe dimensioning.

 

[cornemo]

Thanks for your replies. Still my original concern is there: Does NFPA explicitly tell that the manufacturer/supplier must do the engineering/flow calculations?

 

[rbulsara]

Whoever is making the final decision as to size and layout , which means "design", should do the calculations and take responsibility for it. It does not matter to NFPA or the authority having jurisdiction, as to who the "engineer" works for.

Set of design documents are not the final shop drawings.

Rafiq Bulsara

http://www.srengineersct.com

 

[cdafd]

Sounds like it is a specific requirement by the one paying the bills, regardless of what nfpa says

 

[pipesnpumps]

The NFPA does not specifically state that the manuf.or supplier must do the calcs.

This is no different than sprinklers.. The engineer can GUESS at the pipe routing and do calcs, but until each head is laid out and the pipe is installed, the final design calcs cannot really be done..

Same for clean agent systems. The amount if liquid agent delivered to each nozzle depends on the final physical configuration, and in the case of clean agent systems the system manufacturer has specialized software to calculate the liquid mass fraction at each tee, discharge time, etc.. The specifying engineer does not have this knowledge, heck alot of the time they don't even ask for any given extinguishing or design concentration. As an AHJ I require the installing contractor to provide these calcs as part of their shop drawing submittal.

As others have said, an AHJ doesn't care who does it as long as it is done right. I don't see how an independent third party can calculate foam injection for a system they didn't design, but I am not well versed in that subject.. I would think there are manuf. specific issues with such a system to ensure proper mixing and flowrates of water to foamer.

To put it in simple terms, and to repeat what was said above, whoever has the final say and full knowledge of the design of the system must do the calcs. I would say the terminal owner is correct, but I would check with the foam system supplier to find out the usual process..

 

[b1ueshift]

I don't think you will find anything in any NFPA standard that says a manufacturer should design the system. NFPA standards generally don't say who is responsible for what. This is a contractual matter which is outside the scope of a typical standard.

I assume you're talking about medium expansion AFFF type system with a venturi type foam inductor.

In my experience with foam systems, the most reliable way to guarantee that a system works within specifications is for the installing contractor to do a discharge test, gather up a sample of foam and sent it to a laboratory for testing.

In my experience as a former Tyco employee, they will generally only do this type of system calculation if they are the installing contractor (Tyco owns a number of installation contractors around the world).

 

[b1ueshift]

I think if the terminal owner wants the calculations to be done by the equipment supplier, they will need to go to a company like Tyco and give them a contract to design, supply and install the system completely.

Otherwise, you can likley get a supplier to have a look at the calculations, but they won't do it for money, they will have a 'free look' without a contract and accept no liability if these calculations turn out to be wrong.