TECHNICAL BULLETIN 1128 UPDATES

You may recall our recent email newsletter, blog, and LinkedIn/Facebook postings of our Technical Bulletin 1128 “MECHANICAL INSULATION IN TYPICAL REFRIGERATION APPLICATIONS”.

 

Responses to our Bulletin have been very positive, and our friends have made some good suggestions/clarifications that we thought we should consolidate and send along.

Listed below are comments from a few Followers along with our response to each. Thank you to each and every one who responded. Your questions and comments are appreciated.

·         The Bulletin states that EPS and XPS melt at 165°F and that is not technically correct. We should have rather said they begin to “soften” at 165F. Yet we believe the ultimate conclusion remains the same - -  that the maximum service temperature is generally 165°F for both EPS and XPS.

·         The Bulletin’s data on XPS was based on public data then available on the major manufacturer’s website.  We overlooked data from another XPS manufacturer that more recently entered the XPS billet market. This newer manufacturer creates billets by gluing together sheets of XPS.  These billets have a stated Water Absorption (WA) of 1.0% versus the 0.5% presented in the Bulletin, and the actual range for WA can be from 0.3% to 1%.

·         The new manufacturer of XPS also states R value is 5.0, but the manufacturer does not indicate (on information available to us) whether this is an “aged” value or an “initial”.  The 3.9R value stated in the Bulletin is from the supplier of XPS billets that are a continuously extruded material, and the 3.9R is presented as an aged value per ASTM procedures.

·         Based on some test results just received for Phenolic, we should update its WVT to 3.3 perm-in and its WA to 0.9% by volume.  In the Bulletin’s Table 2 (Water Vapor Transmission for Different Insulants) this would place it after expanded polystyrene and above Trymer 2000XP polyisocyanurate when sorted by WVT. Note that the Phenolic properties still meet the ASTM C1126 standards for both WVT and WA. 

Dyplast’s Technical Bulletin has been updated and is available at:  http://www.dyplastproducts.com/Customer_Bulletins/TECHNICAL_BULLETIN_1128.pdf.

As always, Dyplast welcomes comments and suggestions and strives to present accurate information useful to the industry.

Dyplast updates Technical Bulletin: Mechanical Insulation for Refrigeration Applications

 [Read More: http://is.gd/HuNXzq]

 Summary: Manufacturers and suppliers of mechanical insulation and system accessories typically provide datasheets listing a host of physical properties. This Bulletin offers that the importance of thermal conductivity (k-factor[1]) and water vapor transmission (WVT[2]) of the insulant typically far outweighs the impact of other physical properties. Thus refrigeration system specifiers, engineers, procurement managers, contractors and owners should focus heavily on these two physical properties when comparing alternative insulation materials.

 In essence, compromising the k-factor of the insulant costs a lot of money via energy losses as well as process inefficiencies. Specifier/engineers and end-users should strive for a credible cost vs. benefit analysis before thermal conductivity is sacrificed for the sake of another physical property.

 Vapor barriers, on the other hand, are the first line of defense against moisture intrusion - - with the insulant as backup defense. Since there are now several suppliers offering zero-perm sheets, tapes, and mastics, specifiers and owners have no reason to compromise by selecting a vapor retarder with poorer perm ratings. The permeance of the insulant, as a backup to a damaged or a poorly-installed vapor barrier, is also a critical factor when selecting an insulant since over the life of the system it may be a lifesaver.

 Of the insulant and vapor barrier alternatives available, Dyplast’s ISO-C1^® polyisocyanurate is the obvious choice for refrigeration applications. ISO-C1’s combination of 5.7 R-factor per inch (at 75°F) and WVT permeability of 1.65 perm-in is superior to any other alternative insulant, which is each handicapped by either a lower R or a higher WVT. And for vapor barriers, DyPerm^™ Wrap and Tape offer zero-perm performance, besting the better-known alternatives.

 

 [Read More: http://is.gd/HuNXzq]

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[1] Simplified, the k-factor (thermal conductivity) is the measure of heat that passes through one square foot of material that is 1 inch thick in an hour per unit temperature difference.  The lower the K value, the better the insulation. C-factor is the k-factor divided by the thickness of the insulation material. The R-factor per inch can be determined by R=1/k.  The higher the R factor, the better the insulation.

[2] The Water Vapor Transmission Rate of a material is referred to as its permeability, stated in perm-inches; independent of the materials' thickness. Dividing the permeability of a material by its thickness gives the materials' permeance, stated in perms. ASTM E96 measures a material’s rate of Water Vapor Transmission per unit area per unit of vapor pressure differential under test conditions, expressed as perm-inches (grain/hr·ft²·in Hg·in) of thickness.