Safety & Security Window Film
The primary function of safety window film is to hold glass intact in the event of it being broken. The likelihood of injury to person or property is great in the course of normal glass breakage. It is proven that the application of safety film to existing glass can reduce damage and injury.
Many different events may occur that result in glass breakage. The nature of the event is likely to determine the type and extent of property damage and personal injury. The manner in which glass breaks is important, as it has a bearing on the above mentioned factors.
Who Buys Safety Film?
Anyone who wants to protect themselves from injury due to flying glass shards from acts of terrorism, vandalism, smash-and-grab burglaries and natural disasters. Other individuals who purchase safety film are institutionalized buyers or large corporate purchasers. Often these companies are multi-national companies or government buyers, e.g. General Services Administration, who decide on the purchase of safety film for strategic reasons related to their permanence in a given marketplace and to their own individual security concerns. BP made it a policy some years ago to install safety film in their office blocks and gas stations around the world. IBM, who instituted a similar policy, applied safety film to their buildings around the world some years ago.
Glass breakage occurs in one of the following ways:
- Thermal stress from absorption of solar radiation
- Tensile stress from the weight of the glass itself
- Mechanical flexing stress, i.e. from wind
- Impact stress from flying objects
- Twisting stress from building movements
There are many different events that can occur that will give rise to any of the above conditions, resulting in glass breakage.
Human Impact – Accidental Glass Breakage & Safety Film
One of the major causes of injury is human-to-glass impact. For this reason, there is existing legislation that covers the use of safety glazing materials in certain building constructions. This legislation is designed to protect individuals from bodily harm, should they walk into or through the pane of glass. The major cause of injury to the human body when impacting a pane of glass is what is known as the “guillotine effect.” This is where the person walks into or through the pane of glass with great speed. By the time the individual realizes that they have walked into the glass, they are already in a position where they have broken the pane of glass and do not have sufficient time to back-track. As soon as the glass is broken, due to the effect of gravity, it falls and injures the person.
Safety film decreases and virtually eliminates injury from this type of human impact. The glass, while it may be broken or cracked, remains adhered to the film, and in most cases, is still intact in its frame. The tensile strength of the film, coupled with its elasticity and high resistance to shear, greatly removes, if not virtually eliminates, the ability of a person to walk through a pane of glass.
This product can also be fitted to residential sliding doors and glass doors, particularly in areas where children are present. It may also be fitted in other risk areas such as sliding doors which lead to swimming pools. There is a high incidence of people walking through sliding glass doors near swimming pools, caused primarily by surface water glare and the presence of slippery surfaces around a pool.
Thrown Objects – Baseballs, Golf Balls and Other Threats
Many windows are broken either intentionally or unintentionally by thrown objects. Whether this is a child accidentally throwing a baseball through a window or a smash and grab robbery attempt, the results are the same. The projectile hits the glass with some degree of velocity, breaking the glass inward. This causes large dagger-like shards to fly into the room. Not only does this pose a risk to property, but it also poses a risk to unsuspecting individuals. Whether at home or in the office, people tend to put furniture near windows in order to enjoy the benefits of light, warmth, and view allowed by large windows. In the event of a thrown object, this presents the likelihood of injury.
Adding Security Film to Prevent Theft
In the case of retailers, there is a two-fold problem associated with a thrown object. First of all, the resultant glass shards can damage the merchandise on display in their windows. Secondly, because the glass generally breaks and collapses, it gives the robber an opportunity to quickly and easily reach into the window and remove something. The application of safety film to these windows will reduce, if not completely eliminate, both damage to people and property. In particular, to prevent a break-in installing security film (which is thicker and stronger) is recommended. Because the polyester film has a high degree of elasticity, it is resistant to such breakage. The type of object thrown will determine the chance that that object has of penetrating both film and glass. In most documented cases, the pane of glass itself remains intact in the frame with only a small hole where the object penetrated. This sustained protection serves to thwart the would-be smash and grab burglar. Should the robber persist in the attempt to gain entry into the premises, repeated efforts to smash a hole through the glass and film or to enlarge the existing hole will have to be made. The resultant time delay and noise factor is generally sufficient to scare off most would-be robbers empty handed – making an investment in security film well worth it.
Glass Broken From Explosions
Security Film offers “Bomb Blast Mitigation”. There are many types of explosions which can be accidental or intentional. The majority of accidental explosions are related to industrial manufacturing processes and can result in massive devastation. Intentional explosions are often motivated by political or revenge motives. Explosions may be caused by specialized explosive devices such as plastic explosives, hand grenades, or in the case of industrial explosions, gas leaks.
Whatever the cause, the results are the same. The explosion, by displacing air, creates a shock wave or (as it is more commonly known) an over pressure. This over pressure results in a vacuum being created where the blast has pushed air away from the blast center, generating a shock wave. Depending on the size of the shock wave, this could be up to several miles away from the initial explosion.
When the shock wave hits the glass, it causes it to break. The incidental area of damage surrounding the blast center depends upon the amount of energy the shock wave carries with it. The intensity of this energy will vary according to the distance of the window from the origin of the blast and the type and nature of the explosive. Over and above the possible damage to human life, the damage to property caused by shock waves and glass pressure is significant and can result in the partial or complete destruction of the contents of the building.
Installing Security Window Film has many benefits to minimize damage, and is why US Homeland Security specs safety & security film for their offices.
First, because the film has the ability to stretch without tearing it has the ability to absorb a large degree of the shock wave. As this large pressure of air moves towards the glass and pushes the glass inwards, the glass eventually gets to a point where it cracks and breaks. However, the film applied to the rear of this pane of glass continues to absorb the shock wave and stretches until it reaches the point that it can no longer bear the pressure, at which stage it will burst. In some cases, the shock wave, while great enough to break the glass, is not enough to shear the safety film. This results in the pane of glass being broken but held intact by the film. In these cases, not only are there no injuries, but there is no damage to the property inside the building. In other cases, the shock wave is sufficient to break the glass and shear the film. In a majority of these cases, the glass collapses in one pile attached to the safety film with minimal damage and virtually no injuries. In most cases, no less that 95% of the glass remains affixed to the film.
The initial shock wave itself creates a vacuum. Because of the vacuum created by the over pressure of air, there is an immediate rush of air back to the origin of the explosion. This causes the glass to be pulled back towards the original direction of the shock wave. This is why after an explosion the glass is in a convex rather that concave position. This is a major cause of concern because in the event of a skyscraper or multi-story building, the implosion force may be sufficient to pull that window from its frame. When there is a shock wave, the glass breaks, and the resulting implosion sucks it out into the street below, before the glass has had an opportunity to fall into the interior of the building. This causes a rain of thousands of glass shards onto the street below. This could easily occur in a crowded city center at lunchtime, and the injuries to people in the street below could be substantially greater than to the few inhabitants in the building at that time of day. In the majority of cases, if these windows had been coated with safety film, a large percentage of the window would have remained intact in the frame with most of the broken glass shards adhering to the film.
Safety Film for Extreme Weather Protection
Weather and geographic conditions can result in a variety of natural catastrophes, the most prominent of these being hurricanes and earthquakes. The nature of the stresses put on glass as a result of these two natural events differ somewhat.
Hurricanes produce intense winds which as in the case of explosions, create over pressures or pressures great enough to break glass. There is a difference between hurricanes and explosions. In the case of most explosions there is a single blast, whereas hurricanes sustain winds over several hours. This continuous buffeting of the glass may well result in breakage. Again, as in explosions, this over pressure of air bursting into the building is capable of creating a large degree of damage which is somewhat intensified by the addition of flying glass fragments, wind, and rain.
Another important consideration in the case of hurricanes is that the windows often form one of the weakest points of a building’s envelope. In the case of houses, the wind gets through the windows and into the structure where pressure accumulates and often results in the roof being blown off the house. This was particularly evident in the case of Hurricane Andrew in Miami, Florida during August 1992. In fact, so much attention was drawn to that single factor that Dade County changed the building codes so that window may be more adequately protected.
Safety film offers a high degree of protection in the case of such sustained winds. Should the winds get to the point that the glass can no longer hold the pressure, in many cases, the glass will break and the film will shear to some degree. The film and glass will often remain intact in the frame, preventing wind and rain from entering the building. At a minimum, it will prevent flying glass shards. This alone helps protect your home during mild hurricanes.
IMPORTANT NOTICE: This product is not approved in the State of Florida for use as hurricane, windstorm, or impact protection from wind-borne debris from a hurricane or windstorm. In compliance with Florida Statute 553.842, this product may not be advertised, sold, offered, provided, distributed, or marketed in the State of Florida as hurricane, windstorm, or impact protection from wind-borne debris from a hurricane or windstorm.
Safety Film for Earthquake Protection
The stresses caused by earthquakes are somewhat different from hurricanes and are related to twisting or mechanical flexing of the glass. The intensity of the earthquake will largely determine whether the glass breaks. Other contributing factors are the design and method of construction of the building. In the case of earthquakes of significant magnitude, thousands of panes of glass can be broken. In the Whittier, California earthquake of the late 1980’s. more than 110,000 panes of glass were broken. Because there is no implosion factor involved, this does not generally pose as great a threat as a large explosion. Yet, there is still a distinct possibility that a large portion of these panes of falling glass will result in substantial injury. Safety film will help hold the glass together in the event of breaking and can hold the glass into the frame to prevent further damage.