Frequently Asked Questions | glassmac

Frequently Asked Questions

You could find frequently asked questions about Insulated Glass (IG) Unit production.

Insulated Glass Unit (Double Glass - IG Unit)

In order to prevent one layer glass disadvantages, insulated glass units developed.

Definition of a Gas-Filled Unit

A gas-filled unit contains a gas or gas mixture introduced into the unit for the purpose of significantly improving the thermal and/or sound insulation properties beyond that of an air-filled unit. The type(s) and quantity(ies) or gas must be specified.

Why Gas Filling?

The purpose of gas filling is typically to reduce the heat transfer and improve the energy efficiency of the insulating glass unit. Gas filling can also be a means of reducing the sound transfer through an insulating glass unit and improving the acoustical properties.

To further improve thermal properties, IG units are sometimes filled with inert gas. Regular air in the space between the lites tends to circulate, down to the cold surface and up to the warm, creating heat loss by convection. Certain gases reduce this convection and conduct less heat than plain air.

Which Type of Gas?

For better thermal insulation, gases do have to offer a low heat conductivity, but for practical reasons should also be cheap, colorless, nontoxic, odorless, non-flammable and non-reactive with glass, sealants and spacer material. The so-called "noble gases" Argon and Krypton offer these properties. 

Due to its very cheap price and high availability worldwide, Argon is used in most applications. Krypton is significantly more expensive and therefore used less often, eventhough it achieves great results even inside unit interspaces thinner than 8 mm.

Characteristics of Argon Gas?

Argon is colorless, odorless, non-flammable, non-reactive, inert gas and nontoxic as a solid, liquid, and gas. Argon is chemically inert under most conditions and forms no confirmed stable compounds at room temperature.

Effects of Gas Filling to Insulation

       PRODUCT

GLASS THICKNESS

Insulating Glass Unit (R Values) 
W/m²K (EN 673)

     (12 mm)
Spacer

    (16 mm)
Spacer

Air

ARGON

Air

ARGON

ISICAM KLASİK (Clear Float Glass)+ (Clear Float Glass)

4 mm + 4 mm

2.9

2.7

2.7

2.6

6 mm + 6 mm

2.8

2.7

2.7

2.6

ISICAM SİNERJİ (TRC Ecotherm 2)+ (Clear Float Glass)

4 mm + 4 mm

1.6

1.3

1.3

1.1

6 mm + 6 mm

1.6

1.3

1.3

1.1

ISICAM KONFOR (TRC Ecosol 2)+ (Clear Float Glass)

4 mm + 4 mm

1.6

1.3

1.3

1.1

6 mm + 6 mm

1.6

1.3

1.3

1.1

Which Concentration of Argon Gas Should be achieved?

It is your own choice to define the properties of your products, and that is also true for the concentration of Argon in your units, and for the consecutive properties of your product. But if you define them once, you have to obey your own specifications for all units of this type of product. Thus you have to make sure that your gas filling concentration is reliable and stable. With several gas filling techniques, it is possible to receive a gas filling concentration of 90 %. Therefore typical products are based on this definition as well. Eventhough you are free to aim at other values, this value is used in most cases and 90 % +/- 5% is somehow a standard today.  

According to Insulating Glass Manufacturers Alliance (IGMA) guidelines, the gas fill level of an IG unit, if it is declared ‘gas-filled,’ must be at least 90 percent. (European standards [DIN 1286, Part 2] specify a maximum permitted gas loss of one percent or less per year. There are no comparable North American standards.)

Is it difficulty to purchase Argon gas?

Argon can be bought by most local gas suppliers worldwide as it is frequently used for welding purposes as well. No high purity is needed. 

Sometimes transport and renting of gas cylindres is more expensive than the gas itself. Very few safety rules should be obtained, as Argon is not at all harmful., but non-toxic and non-flammable. 

Does Argon Stay Inside the IG Units?

Sealants are designed to offer a loss rate of Argon below 1% per year. Infact the typical retention values are much better. Argon and Krypton can be assumed to stay inside the unit for decades. However, this is very much dependent on the sealing workmanship in production. Certainly discontinuities of butyle (promary sealant) cannot be accepted at all. 

Several techniques are used to fill the IG cavity. However all techniques result in a mixture of fill gas and air. It is generally accepted that the IG unit should achieve a 90% fill gas concentration. In time this concentration will gradually evaporate, at a rate estimated from 0,5 to 1% per year. IG units filled with argon do not degrade significantly until they reach 75% concentration, which means up to 20 years of durability.

What are Important Properties Distinguishing Manual Gas Fillers?

In the early days, gas fillers needed an information about the units´ dimensions, as the volume to be filled had to be calculated. Filling was time-controlled, based on the asssumption of a given gas flow rate. These fillers are no longer used in Central-Europe at all, as they were found to be unreliable and too complicated in daily use.

Nowadays, gas fillers have an individual gas sensor for each filling output, which checks the actual concentration reached, on-line. If the wanted concentration is reached, the gas filler stops automatically. Thus, operators only have to press a button, while the gas filler does all the rest.

Even calibration nowadays can be done without external intervention, fully automatical. Any adjustment and external calibration needed would only be a source of problems. Gas Fillers should work as easy as possible, as unskilled workers should be able to do this work.

Suction Controlled High Speed Gas Filling

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How to Test Argon Gas Filling?

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