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Circle-D Posted: Sep 24, 2010 10:45 PM	thermal barrier needed here?? Mike, I have a customer that wants me to spray the outside of a pellet dryer. This is a horizontal cylinder 10'6" in diameter and 32' long. The operating temperature is about 170 degrees. This dryer is outside of the building. The burner that provides the heat is fired by sawdust but there is no danger of the flame getting near the foam. I assume where this machinery is located outside that no thermal barrier would be needed, only a coating to protect from UV. Am I correct in this assumption?? Thanks for your reply.
mason Posted: Sep 25, 2010 02:13 PM	With the operating temperatures of 170 degrees F, you want to make sure they don't overheat the tank. Sometimes the foam is so energy efficient the temperatures raise over 200 degrees. If the foam gets too hot it will discolor, then char affecting the physical properties and adhesion. So, to be safe get some stick on temperature sensor disks. (typically available at at sandblasting supply store that specialzes in tanks). They change color at different temperatures. Get some that change at 200 degrees and at 180 degrees. That way if the foam blisters due to high temperatures you have some proof it wasn't a bad foam application. I'll let Mike handle the thermal barrier issue, but being external tanks there are different rules.
Circle-D Posted: Sep 25, 2010 09:28 PM	Mason, Good idea with the discs. I assume you would install them on the surface of the foam after it has been sprayed? I plan on using a high temp foam from NCFI. It goes by 14-006, have you any experience with this. I could not find an ESR on it. The salesman will get back to me on Monday. The data sheet says "continuous service maximum temperature exposure should not exceed 250F. Design to tolerate limited exposure to 300F. I figured this would be enough cushion as to not push the foam to its limit all the time. What do you think?
mason Posted: Sep 27, 2010 06:57 AM	Actually you place the thermal discs on the metal. Then yourI first pass is at 1/2 inch so they don't get too hot. I am very conservative when reading data sheets. After years of spraying hot tanks, I have learned to not trust surfaces that reach more than 200 degrees, regardless of the data sheet from the manufacturer. But it is true that some foams can take significantly more heat than others.
Posted: Sep 28, 2010 12:22 PM	Skip, Thermal Barrier requirements are only an “interior” requirement involving “enclosed occupied spaces”, so you are correct in your assessment. However, there may be other code requirements that come into play. This would depend on the cylinder’s proximity to other buildings, power lines, pipes, instruments, walkways, etc. Make sure you are made aware of all other conditions in the immediate area where this cylinder is located to be sure. Also, the burner may be of some concern. Even though the flames might not impact the foam, the heat generated might, depending upon the configuration. Again, as I keep mentioning in other discussions, you have to keep thinking of “worst case” scenarios. I do have considerable experience with fire issues in refineries and other industrial settings, so if you know the details, I will be happy to help. (Thanks Mason for your input, as my knowledge of such issues is very limited!) Mike Kiser

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Circle-D

Posted: Sep 24, 2010 10:45 PM

thermal barrier needed here??

Mike,
I have a customer that wants me to spray the outside of a pellet dryer. This is a horizontal cylinder 10'6" in diameter and 32' long. The operating temperature is about 170 degrees. This dryer is outside of the building. The burner that provides the heat is fired by sawdust but there is no danger of the flame getting near the foam. I assume where this machinery is located outside that no thermal barrier would be needed, only a coating to protect from UV. Am I correct in this assumption?? Thanks for your reply.

mason

Posted: Sep 25, 2010 02:13 PM

With the operating temperatures of 170 degrees F, you want to make sure they don't overheat the tank. Sometimes the foam is so energy efficient the temperatures raise over 200 degrees. If the foam gets too hot it will discolor, then char affecting the physical properties and adhesion. So, to be safe get some stick on temperature sensor disks. (typically available at at sandblasting supply store that specialzes in tanks). They change color at different temperatures. Get some that change at 200 degrees and at 180 degrees. That way if the foam blisters due to high temperatures you have some proof it wasn't a bad foam application.

I'll let Mike handle the thermal barrier issue, but being external tanks there are different rules.

Circle-D

Posted: Sep 25, 2010 09:28 PM

Mason, Good idea with the discs. I assume you would install them on the surface of the foam after it has been sprayed?
I plan on using a high temp foam from NCFI. It goes by 14-006, have you any experience with this. I could not find an ESR on it. The salesman will get back to me on Monday. The data sheet says "continuous service maximum temperature exposure should not exceed 250*F. Design to tolerate limited exposure to 300*F. I figured this would be enough cushion as to not push the foam to its limit all the time. What do you think?

mason

Posted: Sep 27, 2010 06:57 AM

Actually you place the thermal discs on the metal. Then yourI first pass is at 1/2 inch so they don't get too hot. I am very conservative when reading data sheets. After years of spraying hot tanks, I have learned to not trust surfaces that reach more than 200 degrees, regardless of the data sheet from the manufacturer. But it is true that some foams can take significantly more heat than others.

Posted: Sep 28, 2010 12:22 PM

Skip,

Thermal Barrier requirements are only an “interior” requirement involving “enclosed occupied spaces”, so you are correct in your assessment. However, there may be other code requirements that come into play. This would depend on the cylinder’s proximity to other buildings, power lines, pipes, instruments, walkways, etc. Make sure you are made aware of all other conditions in the immediate area where this cylinder is located to be sure.

Also, the burner may be of some concern. Even though the flames might not impact the foam, the heat generated might, depending upon the configuration. Again, as I keep mentioning in other discussions, you have to keep thinking of “worst case” scenarios.

I do have considerable experience with fire issues in refineries and other industrial settings, so if you know the details, I will be happy to help.

(Thanks Mason for your input, as my knowledge of such issues is very limited!)

Mike Kiser

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