Certifying insulating glass units

Last year, the European Community published harmonized standards on insulating glass units. Every insulating glass unit put on the market in the EC will carry the CE label starting March 2007.

The CE mark indicates compliance with health and safety requirements set out in European directives, specified in the EN 1279 series. The letters “CE” stand for Conformité Européenne, French for European conformity. The CE mark must be affixed to a product if it falls under the scope of approximately 20 so called “new approach” directives. Without the CE marking, and thus without complying with the provisions of the directives, products in these categories may not be placed on the market or put into service in the 25 member states of the European Union and the members of the European Free Trade Association: Switzerland, Norway, Iceland and Liechtenstein and, on a voluntary basis, Turkey. 

In North America, fabricators  certify insulating glass units and other products. Some U.S. and Canadian IG manufacturers see Europe as an additional border for the export of products and therefore express a desire to have their products meet EN 1279.

Following is a comparison of applicable standards.

Program comparison
EN 1279 is a product standard on insulating glass units consisting of statements like testing, production quality control, and product compliance to durability. These statements are not unlike the requirements in ASTM International’s ASTM E 2190-2189-2188, also known as harmonization of insulating glass standards, used by the Insulating Glass Manufacturers Alliance of Ottawa, Ontario, and the Insulating Glass Certification Council of Henderson Harbor, N.Y., for testing references. First, let us identify the differences, and then study those that appear to be significant.

EN 1279 consists of five major items:
•  Product description
•  Testing on moisture vapor introduction after an artificial aging cycle
•  Testing on gas-loss rate through the seal after an artificial aging cycle
•  General demands on an organization, with an optional reference to the International Organization for Standardization’s ISO 9000 series system certification on quality control
•  Demands on daily production control.

The IGMA guide to quality-control manual, Insulating Glass Manufacturing Quality Procedure Manual, TM-4000-02, consists of the following major items:
•  Material description
•  Testing for moisture-vapor introduction after an artificial aging cycle
•  Gas-content determination before and after an artificial aging cycle
•  General demands on an organization and quality control, based on approximately 20 clauses of the International Organization for Standardization’s ISO 9000 series
•  Demands on daily production control items, like dimensional checks, desiccant loading and washing-water quality control.

Similarities and differences
The above ingredients are generally similar. Following are examples of how far these similarities extend.

1. Product description versus materials description. The harmonized EN 1279-5 refers in clause 4.1 to the product description, detailed in the so-called system description. The requirements of the system description are referred to in annex A of the EN 1279-1. The content consists of an extensive material description, where the IG manufacturer declares that he or she can process these on his or her company’s production lines. It is about identification of the type and brand of sealants, spacer bars, desiccants, glass panes and so forth. Principally, this is not materially different from the material description of the IGMA program. However, the system description also contains the dimensional parameters and deviations from perfect product. This must be set up by the IG manufacturer and expressed in action and absolute limits. Regarding the absolute limits, the IG manufacturer determines the scope of deviations from perfection where this IG manufacturer no longer assures the product’s durability, meaning such products cannot be sold. The action limits relate to deviations from perfection then used as references in the manufacturer’s production quality-control program.

2.  Testing on moisture-vapor introduction after an artificial aging cycle. As usual, there must be proof. All programs contain testing. The EN 1279 refers to this as being the initial type test according to EN 1279-2, under the boundary condition that EN 1279-4 is met via the sealant supplier. The IGMA program refers to ASTM E 2190-2189-2188 for the testing; again, this is testing of the moisture introduction before and after aging. Besides the fact that the aging cyclings are done under different conditions, such as temperatures and humidity, the effect is always to create a combination of environmental, thermometric and mechanical stresses. The principle of the conditions is the same, creation of stresses on the seal edge via pressure-load differences due to temperature changes in the surroundings and in highly humidified external environments to let moisture enter via permeation and leakage principles. After the aging, there is, however, a difference in the determination of the degree of moisture penetration. In ASTM E 2190-2189-2188, it is a pass or no-pass based on dew-point formation, while under EN 1279, the researcher analytically determines the amount of moisture absorbed by the desiccant via the 950-degrees Celsius test, meaning that the actual amount of moisture is measured by gravimetric measurement. A pass or no-pass is defined as a certain value of desiccant loading. In the new ISO drafts on insulating glass units, the ASTM E 2190-2189-2188 and EN 1279 methods are both mentioned.

3. Testing on gas-loss rate through the seal after an artificial aging cycle. The EN 1279 refers to this as being the initial type test according to EN 1279-3, under the boundary condition that the EN 1279-4 is met via the sealant supplier. The IGMA program refers to testing of the gas content before and after aging via gas-content measurements. Under the IGMA program, this procedure is a part of the certification route, if applied. The
EN 1279-3 determines the gas loss via analytical measurement of argon that leaks through the seal edge. Studies have shown that the results of the argon-leak test seem to give more “severe” warnings in practice than have been encountered in field studies. However, it is a part of the compliance for CE marking of IG products, and cannot be omitted. IGMA is performing studies on gas-loss rates to create a better fit to practice. The EN 1279-3 uses the gas-loss rate results only as a pass to a set requirement.

4. General demands on an organization. Both the European harmonized EN 1279-5 and the IGMA require demands on an organization. For IGCC, it is based on the verification of quality-control inspection via a traceability check during an audit and the control aspects through the total organization. For IGMA, it is a more systematic audit for procedures based on quality control. For this, it refers at least to the implementation of approximately 20 clauses fully overlapping those required for an ISO 9000 certificate, if made specific to the production of insulating glass units. The IGMA handbook for quality control gives good suggestions for implementation of specific items by IG manufacturers.

The harmonized EN 1279-5 refers to EN 1279-6 for its requirements. A small subset of ISO 9000 clauses are recognizable here. They include calibration of applied measurement devices, competence and responsibilities of personnel and the release of tasks to personnel, management reviews and documentation of all aspects relevant for insulating glass unit production. However, no details are given in how far one should go. In the EN 1279, reference is made to ISO 9000 to prevent overlap, but it does not require ISO 9000 certification in such cases. This last statement is important since IGMA refers to 20 clauses of ISO 9002:1994. Comparison of the requirements leads to the conclusion that in general demands on an organization, the IGMA program is overlapping the EN 1279-6 completely. But the EN 1279-6 does not overlap the IGMA requirements completely.

5. Demands on daily production control. The EN 1279-6 prescribes detailed tables on incoming material control, process control and product-end control. The EN 1279-6 is the core of CE compliance, and scrutinizing it for overlapping items with other quality programs will be difficult. When looking at the details of EN 1279-6, one finds that manufacturers must keep some records for a number of years. But the items listed are considered normal for good IG manufacturing sites. The requirements in the IGMA program strongly overlap the EN 1279-6, except for specific and mandatory systems of control-table registration directly needed for maintaining product compliance to daily production procedures. Solutions like cross-reference tables from the EN 1279-6 to the IGMA-IGCC or ISO 9000 clauses and procedures are allowed.

Logical differences
On the five issues related to product certification, there are not a lot of differences between the EN 1279 and IGMA certification programs. The differences between the testing procedures are mainly based on historical experiences and choices made in the past. Who knows if these can be harmonized in time.

The general quality demands in the IGMA program are better detailed than in the EN 1279, whereas in EN 1279 the level of detailing is open for any manufacturer as long as the requirements of the factory production control and factory production control tables are fulfilled.   

This difference is logical, since IGMA is a quality certification program, while the EN 1279 is a public CE certification program with the minimal requirements only, even though more is allowed. The table below summarizes the key issues to make the programs complement each other if you are an IG manufacturer and would benefit from having all the certification programs operate as effectively as possible.

The IGMA, IGCC and EN 1279 programs can work together to assure long life for IG units, but it can be challenging to combine the programs. The details of course need to be scrutinized. For more information, contact TNO, IGCC or IGMA.