John D. Cowan & Associates, Inc.
An Ohio corporation founded in 1964

Sketch of Jack
 

 

 

The Real Question:
Are we frying eggs or are we baking bread?

 

     Think about it!! To accelerate curing of concrete, heat of hydration must be retained and in most cases, additional heat energy must be added to the curing environment. The curing environment is "THE ENCLOSED CHAMBER" created by the insulated covers. By definition (Funk & Wagnalls) an oven is: "An enclosed chamber in which substances are heated or cooked; used also for baking, annealing, etc. , as in a kiln or assaying furnace." Without a doubt, the primary objective to be achieved with insulated curing blankets is to "build an oven or KILN" around the workpiece. FOLKS. ..WE ARE BAKING BREAD.

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     Now...as for frying eggs: "To cook or be cooked in boiling fat, as oil, lard, butter, etc.; also to cook with hot oil in an open pan above afire." Clearly,. curing concrete is not even remotely related to "cooking in an open pan above a fire." As a matter of fact, the heat energy we wish to retain should surround the workpiece to augment the heat of hydration of the mass to accelerate the cure. So what does baking bread vs frying eggs have to do with insulated blankets? Well, it has a lot to do with the way the insulating blanket performs. You want and need an insulator that provides the best performance in an oven or kiln application; an insulator that has the best performance or "R" rating based on ASTM 236 -GUARDED HOT BOX TEST. Of the ASTM test procedures that are used to determine "R" ratings, this ASTM 236 test procedure is the purest and truest simulation of actual plant use conditions. ASTM 236 rates the "INSULATING SYSTEM" based on the air-to-air heat transmission from the hot environment to the cold. This is real world testing for insulated blankets for the plant cast concrete industry. Now, you are probably saying, "Wait a minute, what's this about different ASTM test procedures for "R" values? "R" is "R", isn't it?" The answer is; materials have varying heat transfer characteristics under differing sets of conditions. Just as concrete has multiple design stresses depending on the application of load, (e.g., tensile, compression, bending and shear} insulation media has varying "R" properties when dealing with conductive, convective or radiant heat sources. The "R" mode (up, horizontal, down} varies with a given media. All of this means that you must determine which test method most nearly matches your intended use of a product and THEN select the best "R" rating for your application.

     Let's go back now and look at "frying eggs." Where does this fit in this discussion of "R?" We have been told that a closed cell flexible foam product 1/4 " thick has substantially the same "R" value as our PT 55 style insulated curing blanket. It is alleged that our stated "R" values are "not for real" because a 1/4" foam product has substantially the same "R" rating "according to our test." How does Poly-Void answer this allegation ? With a very, very important question!! The question is, "What test procedure did you use?" The answer to Poly-Void's question is --ASTM 177, the guarded HOT PLATE test procedure. In this test folks, WE ARE FRYING EGGS. 

      The test sample is laid on a hot plate and the opposite side, "the cold side" of the specimen is carefully measured for heat transmission by conductance. Frankly, we are surprised that ours performed as well as it did under this gross misapplication. Are we saying that ASTM 177 is not a good test? Are we saying that ASTM 177 is not a valid test? The answer to both, is a resounding NO. What we are saying is, ASTM 177 IS NOT THE APPROPRIATE TEST PROCEDURE FOR CONCRETE CURING APPLICATIONS. You wouldn't ask for a tensile strength test for a product that had to meet harsh compression loads, would you? The same logic must be applied to . insulating products. The HOT PLATE is for "FRYING EGGS" and the GUARDED HOT BOX is for "BAKING BREAD." If you were looking for an insulation media to be placed in direct, intimate contact with a heated surface, ASTM 177 is the test to ask for. If you are looking for an insulation media to create an efficient kiln for curing concrete, ASTM 236 is the REAL WORLD test for you.

Poly-Void's PT series of insulated curing blankets incorporate reflective insulation technology because virtually all of the energy being dissipated from the mass of the concrete, the steel in concrete, the steel forms, and the live steam introduced to boost the curing process is "RADIANT" heat. ..and OUR PRODUCTS REFLECT RADIANT HEAT ENERGY!! Hundreds of successful operating Poly-Void insulated systems support this statement of fact. Don't be misled by inappropriate test data. Question the test procedure. FRIED EGGS HAVE NO PLACE IN YOUR PLANT.

Ralph A. Welch -President

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WITH THE HIGHEST
CERTIFIED R FACTOR IN
THE "UP" (the way you use it) MODE.

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OFFERING THE BEST RETURN ON INVESTMENT AS COMPARED TO ANY OTHER CURING BLANKET YOU CAN BUY, AND THAT IS A FACT.
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