# Wet changed to anti freeze system



## cda (Feb 21, 2011)

I understand the hardware components that need to be added/ changed to convert a wet to an anti freeze system

But would you require it to be recalculated because of the use of Anti freeze solution???


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## forensics (Feb 21, 2011)

have you heard???

No recalc is necessary but ...

ya might want to consider this statement by NFPA

NFPA issues safety alert regarding antifreeze in residential sprinklers

Fatal fire raises concern about antifreeze

July 6, 2010 – The National Fire Protection Association (NFPA) today issued a safety alert recommending that residential fire sprinkler systems containing antifreeze should be drained and the antifreeze replaced with water. The alert follows a research study and an initial set of fire tests conducted after a fire incident raised concerns about antifreeze solutions in residential sprinkler systems. The incident involved a grease fire in a kitchen where a sprinkler with a high concentration of antifreeze deployed. The fire resulted in a single fatality and serious injury to another person.

“Fire sprinklers are one of the most effective ways to save lives and property from fire,” said James M. Shannon, president of NFPA. “Until we can provide further information based on additional research that is currently underway, we are urging the public to continue the use of sprinklers but to follow our interim safety guidelines by removing antifreeze if it is in their sprinkler systems.

According to NFPA, the home is the place where most fire fatalities occur, and when home sprinklers are present, the risk of dying in a home fire decreases by 83%.

Shannon said based on testing conducted, 70/30% glycerin and 60/40% propylene glycol antifreeze may provide an unacceptable risk of harm to occupants in certain types of fire scenarios, in particular kitchen grease fires. There were successful tests where kitchen grease fires were extinguished or contained with a 50/50% glycerin solution but it was felt there should be additional testing to more fully understand if there is a risk associated with 50/50% glycerin solution.

NFPA offers the following interim guidance on residential sprinklers

Fire sprinklers are extremely effective fire protection devices, significantly reducing deaths, injuries and property loss from fire.

These systems should not be disconnected.

Until the results of further testing on antifreeze are available, NFPA recommends the following:

If you have, or are responsible for, a residential occupancy with a fire sprinkler system, contact a sprinkler contractor to check and see if there is antifreeze in the system.

•	If there is antifreeze in the system, as an interim measure, drain the system and replace it with water only. Problems associated with freezing of sprinkler pipes can be mitigated by alternative measures such as insulation. NFPA hopes to provide further guidance based on additional testing before the winter freezing months.

•	If you are putting in a new residential sprinkler system, design and install a system that does not require antifreeze.

“We are providing this safety alert as interim guidance based on the information we have right now,” said Shannon. “As soon as more information is available, we will update the public.”


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## forensics (Feb 21, 2011)

However...

If a system is changed to a dry pipe system then the system should be recalculated because the designer must increase the design area by 30% to compensate for the time required to exhaust the air and discharge water.


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## cda (Feb 21, 2011)

not trying to answer my own question:

 NFPA 13 2010 22.4.4.5.1 states "For antifreeze systems greater than 40 gal in size, the friction loss shall also be calculated using the darcy-weisbach equation shown in 22.4.2.1.3


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## Insurance Engineer (Feb 21, 2011)

CDA

I think they need to recalculate the system and here is why.

If they do not have a RPZ backflow devise, they will most likely need one with antifreeze if connected to a public water supply. A RPZ can suck up 5-15 psi, and make the hydraulics go from OK to now you need a fire pump depending on the original safety cushion on the design. Also NFPA may limit the % of antifreeze solution and type as well as requiring premix solutions, check out NFPA.org to be sure.

Also check out NFPA 13, 2010 ed. a lot of new things on antifreeze. If the system is >40 gallon capacity, then it must be calculated using darcy-weisbach  not Hazen Williams, which can require greater pressure depending on the design and antifreeze fluid used.

Other things to consider IF they convert to a dry system:

Increase hydraulic design area 30%

No pendent sprinklers in unheated areas

Pendent sprinklers in heated areas on return bend

Relocate fire department connection

Relocate and repipe the inspectors test connection

One minute to inspectors test connection depending on the size of the system.

Low Points???

Increase testing and maintenance

Remove vane water device if equipped


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## RBK (Feb 21, 2011)

If you are using the 2007 or 2010 editions of NFPA 13, you might want to check out section 22.4.4.5.1, and its commentary if you have the handbook.  The calculations for a wet system would have used the Hazen-Williams folmula, but antifreeze system over 40 gallons require a more complex formula called Darcy-Weisbach.  The simpler Hazen-Williams equation makes some assumptions about the fluid; they are true for water, but not true for antifreeze systems at low temperatures.  If they don't check the calculations with Darcy-Weisbach, it's possible that the system won't have the pressure needed to push the antifreeze out at lower temperatures.

Well, it looks like you found that section without my help.


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## cda (Feb 21, 2011)

Nah cheated. Copied from someone else


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