Standard Test Method for Determination of Long-Term Thermal Resistance of Closed-Cell Thermal Insulating Foams

Designation Number:
CAN/ULC S770
Standard Type:
National Standard of Canada - Domestic
Standard Development Activity:
New Edition
ICS code(s):
91.100.60; 91.120.10
Status:
Proceeding to development
SDO Comment Period Start Date:
SDO Comment Period End Date:
Posted On:

Scope:

This procedure defines the long-term thermal resistance (LTTR) of a foam product as the value
measured after 5-year storage in a laboratory environment and provides means for its prediction based on
an accelerated laboratory test.


This procedure, based on ASTM standard test methods ASTM C1303 and ASTM C518, can be
applied to a wide range of preformed as well as field manufactured insulating foams. This procedure
estimates the change in the thermal resistivity of insulating foam products by means of slicing and scaling.


This procedure addresses faced and unfaced products without consideration to the effect of facers
on the LTTR of the product.


NOTE: This method is not intended for products with impermeable membranes such as those with sheet metal facers, which will retain most of their initial R-values. Reference: M. A. Kabayama, Long-Term Thermal Resistance Values of Cellular Plastic Insulations.


This test procedure is applicable to cellular plastic insulation manufactured to retain a gas or mixture
of gases, other than air, for a period longer than 180 days. If the thermal resistivity of a product changes by
more than 3 % over this 180 day period, this test procedure shall be applied. This procedure specifies
reference time, sampling and testing requirements and is based on ASTM standard test method
ASTM C1303 to determine LTTR for closed-cell foams such as extruded polystyrene, sprayed
polyurethane, and polyisocyanurate.


This procedure does not purport to address all the safety concerns, if any, associated with its use. It
is the responsibility of the user to establish appropriate safety and health practices and determine the
applicability of regulatory limitations prior to use.

Project need:

The following revisions are being balloted for CAN/ULC S770. 1. Clause 1.4 of the Scope states that the standard applies to products that retain a gas or mixture of gases, other than air, for a period longer than 180 days. The second sentence of this clause that specifies that the procedure applies to products that show a change of more than 3% in thermal resistivity after 180 days is not clear as it does not specify how to determine this criterion; it has been removed and replaced with the new informative Annex C (see below Item 6, Annex C). The new Annex would allow innovative products including those with no current material standard to be addressed. At the same time, products such as XPS, PIR and SPF are still required to determine LTTR according to CAN/ULC S770 as per their respective material standards. If a member of those sectors believes they have a product that does not age, i.e. it shows a change of less than 3% in thermal resistivity after 180 days, they can request this be addressed through their respective material standard Task Group. 2. The last sentence of existing clause 1.4 has been moved to new Clause 1.5 and existing Clause 1.5 has been renumbered to Clause 1.6. 3. Referenced standards listed in Clause 2.1 have removed the dates of these standards to be consistent to ULC’s style manual policy. Tables and figures have also been moved to the body of the standard to align with the style manual. 4. Revisions to the reporting section 8.1 K has been made to clarify that it is the average of the initial and the average of the aged thermal resistivity of the surface slices and of the core slices that shall be reported. 5. A new Sub Clause 8.1 O has been added that requires reporting of the LTTR for 25, 50 and 75 mm to be consistent with the requirements of material standards that reference CAN/ULC S770. The existing Sub Clause 8.1O has been renumbered to 8.1 P and modified to specify that the type of blowing agent is to be declared by the manufacturer 6. The addition of a new Informative Annex C is to provide manufacturers, labs, listing and certification bodies information and procedure on how to determine if a new or innovative foamed plastic insulation product with or without an existing standard can be exempted from the requirements to test according to CAN/ULC S770.

Note: The information provided above was obtained by the Standards Council of Canada (SCC) and is provided as part of a centralized, transparent notification system for new standards development. The system allows SCC-accredited Standards Development Organizations (SDOs), and members of the public, to be informed of new work in Canadian standards development, and allows SCC-accredited SDOs to identify and resolve potential duplication of standards and effort.

Individual SDOs are responsible for the content and accuracy of the information presented here. The text is presented in the language in which it was provided to SCC.