Safety
Safety in relation to glass can be succinctly put as:
“Using appropriate products to reduce the possibility of severe cutting
and piercing injuries.”
Safety Glass Classification in Relation
to Accidents
The British Standard used for classification of ‘Safety Glasses’
is BS 6206: 1981 ‘Specification for impact performance
When talking about Human Impact the loading considered
is that which relates to a human being having accidental contact with the
glass. As soon as the word ‘accidental’ is used, the loads cannot
be quantified. The variables that relate to this occurrence are as follows:
- Size and weight of person
- Part of the body that impacts the glass; hand, leg, head, trunk and their
relative hardnesses
- Velocity (speed) of the body when impacting the glass
- Angle of impact; e.g. 90º (normal to) or 5º (glancing)
The only definite conclusions that can be made are that the impacts are from
a semi-hard body acting over a relatively small, unspecified area. The duration
of loading should be short though of indeterminate length. Over the many years
that the subject of Human Safety has been studied, a considerable amount of
data has been collected on accidents. Analysis has given data on:
- The age and sex of those involved in accidents
- The type and position of glazing involved in accidents and has allowed some
quantification of the energy dissipated in an accident.
Classification Methods
The British Standard used for classification of ‘Safety Glasses’
is BS 6206: 1981 ‘Specification for impact performance requirements
for flat safety glass and safety plastics for use in buildings’. BS
6206 requires that the glass does not break or breaks safely (as defined in
BS 6206) when subjected to a pendulum impact from a lead-shot filled bag weighing
45 kg. This impact method is designed to represent accidental impact from
a human body. Three classification levels are achievable – Class A,
the highest, when the impactor is swung through a drop height of 1219mm, Class
B, 457mm drop height, and Class C, 305mm drop height. Class A safety glass
is not required by any of the regulations or standards related to human impact
safety, but is part of the requirement for some types of barriers in BS 6180
‘Barriers in and about buildings’, where containment, guarding,
or prevention from falling is required. BS 6206 defines the term breaks safely
by reference to the outcome of the impact test.
- Toughened glass breaks safely if the glass breaks into
sufficiently small fragments after impact, i.e. if the weight of the 10 largest
crack-free particles weigh less than the equivalent of 6500mm² of the
original sample.
- Laminated glass, wired glass and filmed glass are deemed
to have broken safely if, after the impact, any glass fragments which fall
off are not too large (defined in BS 6206) and it is not possible to pass
a 75mm diameter sphere through any opening formed in the glass. Other glass
products used for glazing, e.g. annealed (ordinary) glass, or heat strengthened
glass, do not break safely, and can only pass the requirements if they do
not break in the test.
The test requires either a standard size or the maximum size of pane available
if this is smaller than the standard size. The test specimen size is 865 x
1930mm.
A safety glass only complies with BS 6206 if it is marked as doing so. The
standard requires that all installed panels shall be marked to include the
following:
- An identifiable name or trademark or other mark capable of identification
through a suitable source
- The type of material
- The number of the British Standard, i.e. BS 6206
- The classification relating to impact test behaviour
(Class A, B or C).
These marks shall be permanent and applied before installation in a position
to remain visible after installation. All suppliers of final cut sizes of
safety glass should mark the glass in accordance with BS 6206.
Safety Considerations in Buildings
Our Technical department is always available to answer your queries and
to offer our expert advice
The Standard Patent Glazing Co. Ltd Flagship House, Forge Lane,
Dewsbury, West Yorkshire, WF12 9EL
Tel 01924 461213 Fax 01924 458083 mail enquiries@patent-glazing.com www.patent-glazing.com
The Purpose of Safety Regulations and Standards
The regulations, standards and expert advice on safety glazing are concerned
with reducing the possibility of severe cutting and piercing injuries. Making
anything completely safe is impossible, and the same applies to glazing.
But it is possible to put appropriate glazing products in the most vulnerable
positions, which are termed “critical locations” in the regulations
and standards. In none of the regulations or standards which make requirements
for safety glass, does the type of glass receive major attention. The requirements
are all couched in terms of conformity with BS 6206 classification levels.
Only where glass can be used which is not required to be a safety glass,
to BS 6206, do the regulations and standards refer to the type of glass.
Hazardous Areas
Over the years since 1966 several studies have been made, around the world,
to gather data on accidents. From this and other research data it has been
possible to produce a list of areas, where, if glass is used in buildings,
there can exist an increased risk of accident and care should be taken on
glass specification.
Hazardous areas:
- Doors and side panels to doors
- Low-level glazing
- Swimming pools and bathrooms
- Buildings with special activity, e.g. gymnasia
Various British Standards have, over the years, given advice onappropriate glass types to use in these various locations. Currently, the subject is covered by Building Regulations, Part N in England & Wales, Part P in Scotland and Part V in Northern Ireland, as well as by BS 6262: ‘Code of practice for glazing for buildings’: Part 4 ‘Safety related to human impact’. Knowing the areas in which safety glasses should be used and the appropriate class of safety glass to use are essential. With this knowledge the appropriate safety glass can be obtained from the glass manufacturer/processor. When installed, safety glass reduces the risks of serious injury in the event of accidental impact.