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shane jamieson Posted: Nov 02, 2009 10:09 PM	Foam-Lok FL 2000 CC When it froths in drum how long to you turn off the heat for ? Or just tun off poly heat and keep iso side heat on ?
mason Posted: Nov 03, 2009 07:10 AM	A very good question. I had this problem frequently when I was contracting in South Texas. Many projects were in remote areas without power except your own generator. Temperatures would soar over 100 degrees for weeks at a time. We would require air conditioners on our trailers and foam trucks to keep the material cool enough to spray. (note: it is a good idea to have the ability to both heat and cool your trailer or truck to maintain manufacturer's recommended storage temperatures of material.) But, if the crews forgot to run the AC the whole drum would turn to froth. In extreme situations, the foam would spout like a geyser when it was opened. You would not want to spray while it is a froth. If the drum pumps pick up froth instead of liquid, the drum pumps can cavitate causing off ratio foam and a distorted spray pattern. If that is the case, you just have to move the drum to a cooler location and wait for the froth to dissipate. This will take some hours. The blowing agent should return into solution if allowed to cool. Some systems may require agitation to reblend the components) (note; the foam may have a slightly higher density because some blowing agent would be lost when it frothed.) I have sprayed water on the bottom of hot drums to cool them down when spraying in very hot temperature (over 100 degrees F) and there was no other way to cool the drums down. It worked fairly well, but be sure you do not allow any water to get inside the drum. Another technique that can reduce the potential for the b side to froth is to lay a nitrogen blanket over the B side. This reduces the frothing potential. If the drum is full or near full, the froth may only be at the top of the drum and not extend to the bottom. It may still be liquid at the bottom. You can very easily check this out by extending a clean pipe into the drum and drawing out material from the bottom of the drum. If it is liquid, then you can spray with this. Just be sure not to spray the whole drum out, since the froth will eventually be picked up as you use material. (in this circumstance change drum pumps after you get to the bottom 1/3rd of the drum). Sometimes the transfer pump action can cause the liquid to froth if it is too high a temeperature in the drum. So watch out for this situation also. As you suggested vary the heat to account for the elevated temperature of the b side and the a side. Your supplier should have the temperatures recommended for each side on the material data sheet. Take a thermometer and check out the temperature of the foam coming out of the drum (some rigs have temperature gauages at the incoming proportioner pump screen). If the incoming temperature is higher than the manufacturer's recommendations, it would not be advisable to use that foam until it cools.

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Comments

shane jamieson

Posted: Nov 02, 2009 10:09 PM

Foam-Lok FL 2000 CC

When it froths in drum how long to you turn off the heat for ? Or just tun off poly heat and keep iso side heat on ?

mason

Posted: Nov 03, 2009 07:10 AM

A very good question.

I had this problem frequently when I was contracting in South Texas. Many projects were in remote areas without power except your own generator. Temperatures would soar over 100 degrees for weeks at a time. We would require air conditioners on our trailers and foam trucks to keep the material cool enough to spray.
(note: it is a good idea to have the ability to both heat and cool your trailer or truck to maintain manufacturer's recommended storage temperatures of material.)

But, if the crews forgot to run the AC the whole drum would turn to froth. In extreme situations, the foam would spout like a geyser when it was opened.

You would not want to spray while it is a froth.

If the drum pumps pick up froth instead of liquid, the drum pumps can cavitate causing off ratio foam and a distorted spray pattern.

If that is the case, you just have to move the drum to a cooler location and wait for the froth to dissipate. This will take some hours. The blowing agent should return into solution if allowed to cool. Some systems may require agitation to reblend the components) (note; the foam may have a slightly higher density because some blowing agent would be lost when it frothed.)

I have sprayed water on the bottom of hot drums to cool them down when spraying in very hot temperature (over 100 degrees F) and there was no other way to cool the drums down. It worked fairly well, but be sure you do not allow any water to get inside the drum.

Another technique that can reduce the potential for the b side to froth is to lay a nitrogen blanket over the B side. This reduces the frothing potential.

If the drum is full or near full, the froth may only be at the top of the drum and not extend to the bottom. It may still be liquid at the bottom. You can very easily check this out by extending a clean pipe into the drum and drawing out material from the bottom of the drum. If it is liquid, then you can spray with this. Just be sure not to spray the whole drum out, since the froth will eventually be picked up as you use material. (in this circumstance change drum pumps after you get to the bottom 1/3rd of the drum). Sometimes the transfer pump action can cause the liquid to froth if it is too high a temeperature in the drum. So watch out for this situation also.

As you suggested vary the heat to account for the elevated temperature of the b side and the a side.

Your supplier should have the temperatures recommended for each side on the material data sheet. Take a thermometer and check out the temperature of the foam coming out of the drum (some rigs have temperature gauages at the incoming proportioner pump screen). If the incoming temperature is higher than the manufacturer's recommendations, it would not be advisable to use that foam until it cools.

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