Hot Air Drying

[ryano669]

I am bidding a job involving several preaction systems, where the specifying engineer has asked us to use the "hot air drying method" to thoroughly remove moisture from the preaction systems after acceptance testing. This is one of many steps they are taking to prevent corrosion. The others include a nitrogen generator for air supply, as well as corrosion inhibitor chemicals. I have never heard of the hot air drying method. I have asked for an explanation of the process from the CM, to which they replied you better just have it covered. Does anyone have experience with this method? I envision some sort of heated air supply filling the system, but common sense tells me the air would have to be so hot that it would damage the rubber gasketed fittings and possibly sprinklers. Thanks in advance for your help.

 

[cdafd]

I think that is when the enginneer stands near the pipe and talks??

good question new term


anyway:

http://www.generalairproducts.com/fireprotection/images/stories/DAPDesignDescription.pdf

http://www.generalairproducts.com/fireprotection/content/view/16/88/

 

[cdafd]

have not done cold storage in so long, maybe he means dryer??


7.9.2.4* Air or Nitrogen Supply. Air or nitrogen supply for systems shall be one of the following:

(2) Air compressor/dryer package listed for the application utilizing ambient air

 

[cdafd]

What is a manual dryer or dehydrator package? What is the purpose of a dehydrator?
A manual dryer (dehydrator) is used remove water vapor from the compressed air system. These dryers should not be used for critical applications like freezer rooms.


What are some advantages to using the Dry Air Pac over other air supplies?
The Dry Air Pac is the ONLY FM APPROVED package designed to provide the sprinkler system with moisture free air to a -40° F dewpoint. Its major components are integrally mounted on an air receiver to save floor space and are pre-piped and pre-wired for easy installation. This package eliminates the requirement to pull air directly from the freezer. When pulling the cold air directly from the freezer condensation begins to form in the intake piping which results in ice plug formation. Another drawback from using the cold air is that it prevents the lubricant from circulating properly which decreases both the performance and the life of the compressor.

http://www.generalairproducts.com/FAQ.htm#32

 

[cdafd]

Specify descant air dryers to reduce the amount of moisture
introduced to dry pipe and preaction sprinkler system
piping. This measure is only of value if all trapped water
can be removed from the piping system. Evaporation of the
residual water in the piping is a greater source of humidity
than the amount added in the system air. As an alternative,
nitrogen may be used to limit the amount of oxygen and
available humidity. However, limitations such as availability,
significant cost, or difficulties with transportation or
delivery should be considered prior to installing the nitrogen
system.

http://www.psdmagazine.org/ASPE_memberpdf/20060708/FocusonFireProtection.pdf

 

[stookeyfpe]

I would be very cautious of any chemical additives. In the 2002 edition of NFPA 13 it does not explicitly prohibit the use of additives for control of MIC but I can sure see problems between elastometric seals, accelerated pipe failures because of thinning of metal, and the Plumbing Code official requiring a backflow preventer on the sprinkler system.

As to the original question about the hot air method, I've never heard of it. If the building is heated, can you turn up the heater and open the system at your high and low points?

 

[ryano669]

CDAFD - I should have clarified this is not a cold storage system. It is a large data center. I am guessing the hot air dryer is to evaporate the residual water in the piping after testing. Seems like this would take a significant amount of heat. The compressor is just a standard 60 gal compressor which provides pressure to the nitrogen generator system.

Stookey - I agree we should stay away from chemical additives, but they are specifying the MICclean/MICtreat system. It seems like the industry has taken a hard turn toward corrosion prevention in the last few years.

Thank you both for your input.

 

[cdafd]

sounds like the dryer can be used on any type dry/ pre action system::


Specify descant air dryers to reduce the amount of moistureintroduced to dry pipe and preaction sprinkler systempiping. This measure is only of value if all trapped watercan be removed from the piping system. Evaporation of theresidual water in the piping is a greater source of humiditythan the amount added in the system air. As an alternative,nitrogen may be used to limit the amount of oxygen andavailable humidity. However, limitations such as availability,significant cost, or difficulties with transportation ordelivery should be considered prior to installing the nitrogensystem.

http://www.psdmagazine.org/ASPE_memberpdf/20060708/FocusonFireProtection.pdf

What are some advantages to using the Dry Air Pac over other air supplies?The Dry Air Pac is the ONLY FM APPROVED package designed to provide the sprinkler system with moisture free air to a -40° F dewpoint. Its major components are integrally mounted on an air receiver to save floor space and are pre-piped and pre-wired for easy installation. This package eliminates the requirement to pull air directly from the freezer. When pulling the cold air directly from the freezer condensation begins to form in the intake piping which results in ice plug formation. Another drawback from using the cold air is that it prevents the lubricant from circulating properly which decreases both the performance and the life of the compressor.

 

[cdafd]

if the owner is wanting an sir dryer even though not a cold storage system than guess that is what they get.


there has to be other dryer suppliers::

http://www.generalairproducts.com/fireprotection/images/stories/DAPDesignDescription.pdf

http://www.generalairproducts.com/fireprotection/content/view/16/88/

 

[ryano669]

It isn't the air supply in question. We are using nitrogen as the air supply. The dry pac only prevents more moisture from being introduced to the system. The problem is drying out the residual moisture in the system after acceptance tests. Thank you for taking the time to provide the links.

 

[LCREP]

No water or moisture in a system after it is trip tested? You got to be kidding me. What are you going to do drain every arm over and pendent head on the job?

OH I got it, trip the system, take the entire thing apart, put it out in the parking lot to dry and put it back together, it will be dry then. I sure that makes as much sense as drying the interior of the pipe out.

What stuff has this "specifying engineer" been smoking???


****************************************
Fire Sprinklers Save Firefighters’ Lives Too!

 

[cdafd]

maybe call the company and see if they have a set up that can be used with nitrogen?????


as stated by LCREP do not think there is anything out there to do what you are thinking


I think some one is mixing up fish and chips.