Nitrogen for Ice Plugs
Nitrogen for Ice Plugs
(OP)
We distribute nitrogen generators that filter the oxygen out of air to leave nitrogen present as a supervisory pressure for dry fire protection systems. The main market for this product is the prevention of corrosion in dry fire protection systems. There may be an important market we are missing altogether. We believe that nitorgen will provide a tremendous advantage over simply trying to dry compressed air as by eliminating the oxygen, as well as continuing the drying process, you virtually eliminate condensation. Plus, nitrogen can shrink or even eliminate existing ice plugs. Has anyone had success with nitrogen as a supervisory agent in dry systems for cold storage?





RE: Nitrogen for Ice Plugs
RE: Nitrogen for Ice Plugs
I am wondering about ice plugs in cold storage applications. I have come to find that these dry systems protecting cold storage or freezers, may have ice plugs that have developed between the interface of the cold air and the warm air of the supplied air compressor that prevents the systems from working properly when called upon and there is no required testing or maintenance procedures required to determine if ice plugs are present.
Can anyone weigh in on this idea?
RE: Nitrogen for Ice Plugs
Travis Mack
MFP Design, LLC
www.mfpdesign.com
RE: Nitrogen for Ice Plugs
RE: Nitrogen for Ice Plugs
RE: Nitrogen for Ice Plugs
from NFPA 25, 2011
14.4 Ice Obstruction. Dry pipe or preaction sprinkler system
piping that protects or passes through freezers or cold storage rooms shall be inspected internally on an annual basis for ice obstructions at the point where the piping enters the refrigerated area.
14.4.1 Alternative nondestructive examinations shall be permitted.
14.4.2 All penetrations into the cold storage areas shall be
inspected and, if an ice obstruction is found, additional pipe shall be examined to ensure no ice blockage exists.
****************************************
Fire Sprinklers Save Firefighters' Lives Too!
RE: Nitrogen for Ice Plugs
I have been told that if nitorgen is used as the supervisory pressure as opposed to air, that the nitrogen will not allow condensation to form because the oxygen is no longer present in the compressed air and that with the use of nitorgen, the nitorgen will actually shrink or completely eliminate any existing ice plugs that may be present.
Doea that sound factual?
RE: Nitrogen for Ice Plugs
Once the existing ice plug is removed, the nitrogen could be used to reduce or eliminate the occurrence of future plugs. But, it doesn't seem feasible for it to eliminate a current ice plug - unless I am missing something from my basic chemistry days.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
RE: Nitrogen for Ice Plugs
RE: Nitrogen for Ice Plugs
1. Are the majority of ice plugs in cold storage applications seen at the interface of the cold/warm temperature or are they seen primarily at the drum drip location?
2. When there is an ice plug present, is there a drop in pressure that would register on an air gauge down stream of the plug or does the plug lock in the air pressure?
Thanks for your help with tihs!!
RE: Nitrogen for Ice Plugs
1. Are the majority of ice plugs in cold storage applications seen at the interface of the cold/warm temperature
YES If the air does not come out, the valve, dry or pre-action ( if double locked) does not trip, the fire is not controlled.
2. When there is an ice plug present, is there a drop in pressure that would register on an air gauge down stream of the plug or does the plug lock in the air pressure?
Nope only location of the gauges is at the sprinkler valve, if the ice is plugged you would have no idea by looking at the gauge.
****************************************
Fire Sprinklers Save Firefighters' Lives Too!
RE: Nitrogen for Ice Plugs
Travis Mack
MFP Design, LLC
www.mfpdesign.com
RE: Nitrogen for Ice Plugs
The gauges and pipe are still on the riser side before a plug where the cold and warm meet I do not see how this would work.
Did I miss something??
****************************************
Fire Sprinklers Save Firefighters' Lives Too!
RE: Nitrogen for Ice Plugs
****************************************
Fire Sprinklers Save Firefighters' Lives Too!
RE: Nitrogen for Ice Plugs
RE: Nitrogen for Ice Plugs
I have to assume that the people that write the standards are far more intelligent than myself and I recall there being a pretty thorough description of the new piping requirements (this came about in the 2002 edition) was so that a pressure differential would indicate an ice plug.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
RE: Nitrogen for Ice Plugs
Some ice plugs are solid (100% blockage). Many of the ice plugs in these systems create severe obstructions with partial ice plgs which develop inside the pipe with an open hole in the center (imagine a donut with a very small hole in the middle that runs 6-8 feet long down the length of the pipe). I have seen instances were 90-95% of the pipe cross section of the 8 in. diameter pipe is obstructed by ice. Either way..........the fire protection system will not operate as designed!
The primary location for the ice plugs will be the first few feet as the pipe enters the refrigerated area (caused by condensation over time). ANY moisture inside the sprinkler system piping will eventually find it's way to this section of pipe over time due to condensation laws. This is one of the many reasons why standard dry-pipe valve systems should NOT be used to protect refrigerated area systems; the priming water is drawn into the system and creates the ice plug & also leads to dry rotted rubber seat at the dry-pipe valve.......VERY common problem and a significant percentage of the people in our industry are simply are unaware of this issue. If these "sprinkler people" were knowledgeable in this arena, we would not see standard dry-pipe valve systems protecting these areas and we would see most or all of the NFPA & FM Global required components (including the "easy to remove sections of pipe" for ice plug inspections!).
Instead, many customers think I am trying to make them spend money for expensive alterations simply because some jack-leg sprinkler contractor was the low bidder! I end up spending a significant amount of time explaining the problem and removing sections of sprinkler piping to show the customer the ice plugs; however, this is not enough proof to spend $10,000, so I have to explain the entire condensation process, show them the NFPA documents outlining the proper design and convince them the system is not reliable as installed. WOW, that is a really long run-on sentence!!
RE: Nitrogen for Ice Plugs
Many people are looking towards a regenerative dryer a s asolution to the problem and while this may be helpful, it is not the total solution. If you can eliminate the oxygen through the use of nitrogen as the supervisory pressure, would that prevent condensation from forming?
RE: Nitrogen for Ice Plugs
Now, if the system trips, you will have to be sure to eliminate all of the water and fully displace the O2 in the piping with N2 again to prevent the condensation from developing.
The N2 plan seems more foolproof than the air dryer, but if the system is properly maintained per NFPA 25 with the air dryer, then I would assume that would be effective as well. Again, proper maintenance is the key.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
RE: Nitrogen for Ice Plugs
RE: Nitrogen for Ice Plugs
Any thoughts?
RE: Nitrogen for Ice Plugs
RE: Nitrogen for Ice Plugs
In another application in fire protection, by eliminating the oxygen in the piping and running at least 95% nitorgen, you can eliminate corrosion from developing on metallic pipe.
RE: Nitrogen for Ice Plugs
And if, like TravisMack, you are supporting the claim that condensation forms via oxidation, please explain where the free hydrogen comes from. The half a part per million H2 found in air?
RE: Nitrogen for Ice Plugs
Same could be accomplished using very dry air I imagine, but N2 is likely cheaper to get than -80 dew point air.
RE: Nitrogen for Ice Plugs
The nitrogen generator system also comes with an automatic purge device installed at the end of the system that will purge the nitrogen out of the system at a rate of less than 1pd per 24 hours. The generator is designed to pump to a higher inlet pressure than the static pressure in the system. Due to the low dew point of nitorgen, -40F, it will absorb any residual moisture in the system and through the purging/cycling action, will remove the moisture from the system.
While we know this system performs remarkably well in preventing corrosion on the internal metallic piping, we are now considering the benefits of preventing the build up of ice plugs in cold storage applications.
As you review my prior postings you may see that I am asking for some input as to your thoughts on this system being beneficial to the prevention of ice plugs.
Farthest thing from my intention is to start or suggest any "wild donkey" claims.(I like that expression and will use it in the future with the author's permission.)
RE: Nitrogen for Ice Plugs
RE: Nitrogen for Ice Plugs
RE: Nitrogen for Ice Plugs
I agree that removing O2 will prevent corrosion. I was addressing the condensation bit. Dry air will also absorb moisture. Seems to me you could save a lot of cost by doing all of the above while skipping the nitrogen generating part.
I have no doubt that you could shrink an existing plug by passing a dry gas over it long enough. Water does not need to be liquid to evaporate.
RE: Nitrogen for Ice Plugs
What causes an ice plug to form at the warm to cold interface of a mechanical system?
Is it moisture or oxygen that causes the condensation to form, or is it both?
Is a dry air pack that dries the air as good as a system that dries the air but also filters out the oxygen molecules from the air?