Antifreexe systems for storage

[WallyFP]

Hi,

FM Global 2-0 Section 2.4.7.1 says that a 30% solution propylene glycol antifreeze system is acceptable if the ambient temperature of the protected area is maintained at or above 25°F (-4°C), as well as at or below 200°F (95°C) at all times.

Are there limitations to this (aside from the temperature ranges) or is it a viable option for any wet system design with using FM Approved piping/heads if the protected area is between 25°F and 200°F as noted. I would assume that a premixed 30% propylene glycol solution would need to be used.

I know there was a concern in the past with using them with ESFR heads becuase of combustibility of some antifreeze solutions (primarily greater than 50% mixes), but I wouldn't expect a 30% propylene glycol and 70% water solution to even have a fire point.

Thanks for your time.

Wally

 

[cdafd]

Is this a general question or are you looking at a project??

If so how many sq ft??


Also you may need to calculate the Darcy–Weisbach formula depending I what edition of 13 you design to

 

[WallyFP]

Thanks cdafd,

To your question of what size, I'm looking at it for a system that's about 25k sq.ft. But that was really my question... are there limitations (other than those for wet pipe systems)? Using FM 8-9 (a national recognized standard) as an alternative to 13, it appears to allow (per 2-0 2.4.7.1) the 30% or less propylene glycol (PG) systems as long as the ambient temp is between 25 and 200 deg F. Seems perfect for a 30-35 deg cooler. I would like to use it with K-25 quick respose heads using a design from 8-9 and I can't find any reason that this is not allowed. As to the Darcy Weisbach method, I'm not sure that there would be much difference between it and HW at the proposed temp and only 30% PG, but I agree that calcs should at least be run to determine that.

Thanks for your time.

Wally

 

[Sdpaddler50]

Wally, i have never been involved with one of these AF systems, and only briefly read the FM 2-0 section you reference, but what you are noting sounds correct to me. If this project is for an FM insured (building occupant, or building owner) you should contact the local office of FM. They have a plan review department staffed by an engineer who can answer your questions. For very large, high value projects, FM will often assign an engineer to work directly with you, from design to installation. But, at 25K sq ft, i can tell you this particular project wont qualify for that level of servicing.

 

[WallyFP]

Thanks Sdpaddler50,

It is not an FM insured but I occasionally use FM standards as an alternative to NFPA 13 per the equivalency clause (section 1.5). Funny how now a days some of the FM standards are more friendly than NFPA - used to always be the opposite. I did contact the local FM office yesterday for a clarification of their standard and the initial response was that AF systems could not be used for much other than loading docks, canopies, etc. (<20 heads) - no storage and no large systems. I don't read it this way except for where you have temps less than 25 deg F that require a higher concentration of antifreeze. I have gone back to them to try to clarify - I don't think they see many of these. I think there has a been a reluctance to use AF systems in the past for large systems since PG is a combustible liquid in higher concentrations and it can also become extremely viscous at cold temperatures. There is a small temperature window in which these are applicable. Lots of questions... I appreciate your response and if I get a different ruling from FM, I will provide to the board.

Wally

 

[Sdpaddler50]

Wally, I am an ex FM guy, who has not dealt with these either from a design standpoint. I did do a survey of an existing warehouse about 3 years ago when i was with FM that had a PG system. It was only a brief couple hours i spent there looking at some other issues, but if i remember correctly the PG system protected about 100K sq ft of high pile storage. Yes, the flammability of the earlier PG systems was an issue if i remember correctly as well. You may want to throw this out on a sprinkler forum group. NFSA, AFSA, etc. Also, Travis Mack is often on this board, and he is a sprinkler designer so he may have some insight as well.

 

[Sdpaddler50]

As far as FM being more user friendly for some storage arrays; 8-9 was compltely re-written several years ago. In a nut shell, smart guys with PHD after their name found you can protect high pile storage more effectively with pendent, QR, 165F heads, large orifice heads based on full scale fire testing at the lab to achieve ADD. Keep in mind, they have the largest fire test lab in the world. The "ESFR" term has been done away with, and sprinklers are either "storage" or non storage. These new designs use big heads, and often have hose demands of 250, as opposed to 500. Here is a link to a good article in SFPE.

http://magazine.sfpe.org/sprinklers/whys-behind-fm-global-data-sheets-2-0-and-8-9

 

[WallyFP]

Thanks Sdpaddler50, I also paid my dues with 10+ yrs with FM (pre merger). The protection tables are much more user friendly now, but not so much with 2-0 and the installation guidelines. Yes, the overall water demands using some of the new FM designs are significantly lower than those of NFPA (granted - you have to design to the building height rather than the storage height). I guess everything has a trade off! Thanks for the link.

 

[Sdpaddler50]

Hi Wally, nice to hear of someone else who has left the mother ship and working in NFPA land besides me. Can you shoot me a private email; sdpaddler50@yahoo.com