ISO 16932:2020 “Glass in building — Destructive windstorm-resistant security glazing — Test and classification

BY ANDREA BRUSCHI                                                     
Head of Istituto Giordano S.p.A. Security and Safety Laboratory

The need to specify the windstorm resistance of building components began in the 1990s in the State of Florida when the area was hit by a number of severe destructive windstorms causing extensive damage to homes and many casualties.
 
Thus 2007 saw the publication of the first normative reference, ISO 16932, with the aim of classifying the resistance of security glazing products to destructive windstorms such as tornadoes and/or tropical cyclones (V > 50 m/s).

• Following an initial revision of the standard in 2016, in February 2020 ISO (International Organization for Standardization) published a new edition. The main changes compared to the previous edition are as follows:updated hazard to human life (in storms/cyclones) classifications
• modification of missile impact weight requirements.

Whilst in Florida testing of exterior glazing assemblies, whether window, door, curtain walling or anything else, is compulsory, in other countries such as in Italy, remains a little known standard because it is not mandatory and only over the last decade has the "destructive windstorm" problem affected our country as well.

WHAT ARE THE BENEFITS FOR A MANUFACTURER?
For an Italian manufacturer of special-purpose laminated glass, the main benefit from performing this test is a commercial one:
it is a spectacular test that highlights the need, in the event of tornadoes and/or cyclones, to protect the safety of those living in buildings having large glazed partitions.

THE TEST
More specifically, the standard describes a method to determine the resistance to impact from windborne debris generated during a destructive windstorm and at the same time the resistance to cycles of strong positive and negative pressure caused by gusts of wind.



For this purpose, the specimen is subjected to high speed impacts using an air cannon to propel two main types of missile:
 

• LARGE MISSILE comprising a piece of timber (lumber);
• SMALL MISSILE comprising solid steel balls.

The following table describes the missiles and impact speeds specified in the test procedure:
In order to determine the resistance to gusts of wind, the specimen is subjected to specific cyclic sequences of inward acting and outward acting pressure. At the same time, specimen deflection is measured and details noted of any damage.

Where the air pressure differential P depends on the wind zone in which the glazing is intended to be installed.

The test requires 3 glazing specimens of size L = 1100 x H = 900 mm.
 
 

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