According to the UK Government, “terrorism presents a serious and sustained threat to the United Kingdom and UK interests abroad.”
Although recent terrorist activity in Europe has increasingly involved so-called marauding terrorist firearms attacks, the threat from terrorists using improvised explosive devices still remains.
Where such attacks do take place, particularly in urban areas, most injuries result from the blast damaging building glazing systems. As such, building owners and/or occupiers need to determine if any additional measures are required to mitigate or protect glazing from the effects of a bomb blast.
What kind of buildings can benefit from window protection?
In a bomb attack, a single square metre of glass can produce up to 1,800 deadly shards. These flying glass shards cause more damage, injury and death than the explosion itself. Anti-shatter films can protect embassies, government buildings, corporate and commercial buildings, schools and universities, as well as classified buildings.
A shatter-proof film protects your business, property, employees, and the public by protecting against shards of glass in the event of a natural disaster, civil unrest, or bomb explosion.
A completely clear film, it is very versatile and can be fitted to all areas of a building, providing an economic retrofit solution instantly.
Benefits of bomb blast nets and films
In case your window breaks due to a blast, bomb blast nets or films will hold the broken glass pieces together, maybe even within the frame. Of course, the biggest benefit here is added safety measures, but this can also make it easier for you to get back to work faster. If you need to keep your business open and continue to work, after a window break, you will be able to. The film will just hold the glass shards together until the window is ready to be repaired.
Bomb blast nets and anti-shatter films are easy to install, and when you work with us, a technician will visit your building and add the film to your windows. As an upgrade, it doesn’t take much time to accomplish and is a quick and easy process. The primary reason to install these is to keep your employees and customers safe, should this type of emergency happen.
Bomb blast net curtains (BBNC)
These are normally used in conjunction with anti-shatter film systems to stop the glass being projected further into the building. This type of window protection is particularly recommended for wood framed windows with small panes, such as Georgian style frames.
Using special construction, these nets have a shatter strength of 5kg per square cm. They are flame-retardant to British Standard requirements and are available in various shades. Every bomb blast net is weighted at the hem at the rate of 400 gm per metre. Together with its top rail and retaining box, each net is custom made to the exact window size, which is essential if it’s to provide maximum security.
The bomb blast net’s main function is to catch and retain the many pieces of shattered glass. The fabric spinnakers out and stops the flying shards of glass which, because of the anti-blast film, will be composed of larger pieces travelling at a slower velocity than if the glass was untreated, carrying them safely to the floor and preventing them from flying around the building causing severe damage.
– White mesh polyester filament marquisette fabric
– 400gsm thickness
– 550KTNs bomb blast resistance
– Flexible bottom hem weights
– Fire retardant to BS5867 part 2 type B
– Five-year manufacturer’s warranty
– High and low temp washable
Anti-shatter film (ASF)
Anti-shatter film can be used to hold glass together should an explosion or a break occur, and will often remain in the frame, massively reducing injury and damage.
In essence, the forces required to break the glass are increased due to the additional imparted strength of the protective film. According to the CPNI, this option can reduce the damage of flying shards of glass by as much as 50%.
Where anchoring is specified as a requirement of certain types of buildings, the type of frame and structure will be designed and installed to exact specifications, in order to guarantee optimal performance.
These high-tech safety films are optically clear 50, 100- or 175-micron films which are invisible when correctly applied to the inside of the glass surface. They hold shattered glass in place, and they not only help to contain the bomb blast but they also minimise the effects of bricks and similar items thrown through the glass.
An anti-blast film needs to be applied to the glass; this helps to prevent it disintegrating so that the net can contain it more effectively. Correct installation is vital as every installation is manufactured to precise window measurements in order to perform at its best.
– Protection from shattered glass during a nearby bomb explosion
– Important health and safety measure for government and commercial buildings
– Completely clear and colourless
– Blocks 99.999% of harmful ultraviolet light
An explosion inside or near a building can cause disastrous damage to the building’s external and internal structural frames, and create a massive blast out of razor-sharp glass panes and shards in various sizes.
The Centre for the Protection of National Infrastructure (CPNI) states that up to 95% of all injuries from a bomb are caused by flying or falling glass, and therefore the quality of glazing protection is vital.
Structural characteristics of the building and glazing system may also influence the potential impact, so it may be necessary to get expert advice on these aspects as part of the assessment. There are also many unknown variables, not least the size of the explosion and the proximity to the premise under assessment. The channelling effect of other buildings and street architecture can also change the way the pressure wave affects buildings.
Peel test certification for ASF
The strength and reliability of the adhesive bond used on ASF can be easily tested by carrying out a peel adhesion test. This test has been developed to measure the effectiveness of both newly installed and aged ASF.
Peel test certification for the ASF could be up to 10 years old in some cases, or even in certain brands of film. Any ongoing changes in BoPET (bi-axially-oriented polyethylene terephthalate) manufacturing and the adhesives used, may also mean that previous test results may no longer apply. Evidence of certification should be reviewed to confirm that the film supplied will provide the level of mitigation expected.
Known deficiencies of ASF over time can include loss of strength and the base film becoming brittle due to ultra-violet degradation and loss of adhesion to the glass. These deficiencies are generally not visually apparent so the importance of carrying out the peel test is even more vital. Some of the old films used in the past are also very thin compared to the current standards so they should be replaced straight away, there is no peel test needed as they are inferior to current standards and would fail the test anyway.
Other problems which might affect the useful life of the film can include:
– De-lamination at the edges of the ASF
When should you conduct a peel test?
Peel tests should be carried out between 28-90 days after installation or as and when it is necessary to ascertain the effectiveness of the ASF already in place or gain an indication of how much longer the film may be used for.
For newly installed ASF, peel tests should be carried out following these time frames guidelines after installation:
– 28 days for 100 micron film
– 42 days for 175 micron film
– 90 days for 300 micron film
These time frames are only a guideline as there are elements like tinted glass, window elevation and inside or outside temperature, that will all have an impact. These factors can affect the ability of the wetting solution to evaporate, and therefore the length of time before a film can satisfactorily hold weight may be longer than that quoted above.
Wetting solutions are applied to the ASF before being applied to the glass. Once in position, excess moisture is removed by applying pressure to the film using an outward sweeping motion with a non-scratch plastic application tool. The liquid used in applying the film plays a critical role in the adhesion strength of the film to the glass and its mitigation performance.
Using the wrong wetting solutions like plain water with additives, may damage the adhesive bond between the film and the glass, which means the film won’t be able to contain the glass fragments under a blast load. This issue will not be evident until a peel test is carried out later in the curing period.
Any homemade solution containing alcohol, washing-up liquid, or windshield washer could really damage the adhesive bond and should never be used.
At Grosvenor Contracts, we take pride in offering a personal service, so please don’t hesitate to call our helpful team. We’re always happy to talk and advise you on the perfect solution to your business needs.