large military cold storage facility, sweating lines and ice formation
First time poster, long time lurker. I’m a civilian contractor stationed in the south pacific, Marshall Islands. I’m the department Mechanical Engineer, which stands for Mr. Everything, whereas sooner or later, they'll wordsmith it into being mechanical in nature, even if it’s not.
I’m looking at a problem at a large cold storage facility. The dimensions of the combined cooler/freezer areas are 60' x 130', comprised of both freezers and reefers. The overall height of each cooler box is 21'7". There's been some damming of ice up high in one of the coolers, especially to one corner. My suspicions were there's water coming from above the coolers. Upon in person inspections, this turned out to be the case. The whole building is approx. 8 years old, so not too deteriorated. All the lines look to have armaflex installed in a correct manner, however a majority of them are wet to the touch, some have ice forming at the seams. There’s standing water in quite a few areas, and the water seems to be migrating down the seams of the panels, and in between the walls. I have ice forming on the opposite wall of a freezer, in a 38 degree cooler, but no ice forming on the opposite freezer wall, hence my suspicion of migrating top down. I need to remedy this problem.
There’s a dedicated cooling system/AHU for the space above the cooler boxes in the servicing area, so the air is tempered, not open to atmosphere. The TXV was iced over, but this is the smallest of my problems. Im sure fixing it will help the sweating issues.
1) go over the old armaflex with a second layer for double insulation. This would require new pipe hangers to accommodate the increased diameter.
2) install new armaflex
3) tape all seams of existing armaflex
4) Extend ducting off dedicated AHU to blow over troubled areas (keep in mind, 60’ x 130’ is a lot of real estate).
I know we’ll have to take the freezer out of service to recaulk eventually. I need to fix the sweating issue before I get to this point.
Any suggestions to keep the supply and return lines from sweating and pooling water would be appreciated.
Thanks in advance.
All I can say is that it makes me sick to my stomach to just think about how much work it would be to thaw all of those lines and reinsulate them successfully... Good luck to you
you need to address sealing seams and points of air and moisture infiltration .there should be no way that moisture should seep thru
Do you know what thickness wall the insulation is? Ive had this issue before. If its 3/8 wall there is your problem!
You may need to go with 3/4 or 1 " wall
When you reinsulate you need armaflex glue and then armaflex glue some armaflex tape over the seam to. Do NOT trust the aramflex tape sticky back. Glue the stuff on with armaflex glue. This is going to be labor intensive. Be prepaired to have armaflex glue all over you.
From the pics posted it appears that the insulation has become saturated in some areas and/or the wall thickness isn't sufficient for the application.
Since it looks like 1" wall on the low temp lines, that would suffice according to the general guidelines from Armaflex for refrigeration installations, but since you're in a rather humid climate additional insulation thickness may be needed...even though the space is air conditioned.
I have seen many instances where Armaflex has failed due to moisture permeation over time. My favorite local supermarket has an exposed ceiling and it's quite noticeable after only about 6 years since installation. The only solution in such cases is replacement in my opinion.
Here's the Armaflex websites download page with lots of info which you may find useful:
Thanks for the input. an extra set of eyes and opinion is appreciated.
so this isnt 2 guys, 20 hour job
a couple of questions:
1) can the armaflex be dried out and reused, i.e. retape the seam? this installation is probably one of the newest on island.
2) what about logic of adding another layer over the too of the existing armaflex. ive seen armaflex in worse shape than this, from a visual standpoint, it looks fine. reseal the existing, add one more layer of armaflex.
it seems any direction i go, this will turn into a multi step project, i.e. getting the insulation remedied, drying out the freezer/cooler boxes to seal seams etc.
To determine if the existing Armaflex is salvageable I usually use the squeeze test, which is basically checking for absorbed water. If it's frozen solid it's shot. If water squeezes out like a sponge it's shot.
Originally Posted by cchavis
There's really no way to dry this stuff out so that it's back to original specs.
With the climate you are in the only answer is to thaw it out and reinsulated with new sorry.
What you are seeing is why I try to put lines on inside of box whenever possible. Replace w/ thicker isulation and lower humidity outside box only way to fix.
Thanks for all the input guys, much appreciated. i need to work up the numbers, find some armaflex at a good price!!
you also have the option of jacketing on top of the new armaflex, metal/or pvc /silicone. costly ,but permanent fix, May be good option for customer in high humidity enviroment and large enough operation. stan
Keep it simple to keep it cool!
wow i just looked up Marshall Islands on Google Maps!!! Now that's a remote location!!! The islands look like they are sunk underwater and just the outsides are above water on the satellite view! How on earth do you live there!
Keep it simple to keep it cool!