ABOUT PU FOAM Expanding polyurethane foams have existed for many years but with the upturn in fast track construction necessity has lead to the generic PU foam being modified and tweaked so that it is more suited for todays building methodology.
Hand Held or Straw Foam Applicators are the most common types used. These are aerosol propelled with a simple straw dispenser that attaches to the valve. They have a limited usage life once opened and cannot be reused once they have been restored. See pages 24-25.
Gun Grade or Gun Foam is produced to a predominantly closed cell formulation, unlike Hand Held, which means it yields a higher extrusion rate. The benefit of gun grade is the gun allows for precision application meaning less wastage due to its variable valve. The gun should be purged with the gun foam cleaner after each use. See pages 24-25.
Fire Rated Foam. Normal foams are classed as self-extinguishing which means they will not support flames but they offer protection against them. Fire Rated Foams however, do offer fire retardant properties and are available in both hand held and gun options. With stringent building regulations dictating the use of such products, the correct foams for such applications should be tested to European Standards EN1366-4 and EN1366-3 which has superceded BS476 pt 20.
These foams make ideal backing material to fill joints prior to sealing as the expansion ensures the void is completely filled thereby offering complete fire protection. Fire sealing applications can include: joints between dry wall or composite panels, gaps around window and door frames, gaps around switches and socket points, pipe access openings in order to maintain the integrity of the fire wall. See page 24.
Mega Foam. Bond it have a unique foam that is gun grade quality but in an aerosol format. With a specially patented valve it allows the tin to be used at 360 degree angle with either a special plastic adaptor of with the use of a standard applicator gun. See page 24.
WATCH POINTS Make sure any foam tins are warmed to room temperature prior to use. This can be done by putting it in a bucket of warm water. Do not use naked flames or any other heat source to warm tins as they will explode.
Store foam cans upright whilst stored or in transport. Shake cans vigorously before use and apply foam with the can inverted (unless using Mega Foam). Moisten dry surfaces before application to help the foam cure and improve adhesion. Protect surrounding surfaces prior to application as the foam is incredibly tacky.
Maintain foam guns keeping them clean by using a Gun Foam Cleaner after you change cans. This will prevent the gun from clogging and becoming unusable. Remove excess wet foam immediately after application. Check the manufacture dates as most foam only has a shelf life of 12 months (Mega Foam has 18 months).
Do not puncture tins. Store only at temperatures of between 15 and 200 C, climates
that are too cold or too warm will affect the performance of the foam (Mega Foam has lower operating temperatures). Do not store or use this product in the vicinity of naked flames.
UNDERSTANDING FIRE FOAMS A good example of the benefits of the CEN and ISO “global harmonisation of standards” can be seen with Fire Rated PU Expanding Foam. The German National Standard for these products is DIN4102, there are three classes within this standard: B1, B2 and B3; B1 being the least flammable. However, even the German DIN4102 B1 classification often does not satisfy the building requirements for fire resistance in the UK.
Confusion has been caused by the DIN4102 standard being marketed in the UK as B1 or B2. B2 foams are generally a cheaper option but in terms of their fire resistance capabilities, they are well under par.
It is imperative that if you are using products that MUST comply with fire resistance, then you MUST use a B1 foam. As explained, EN standards are accepted as national standards in CEN member states, EN1366-4 is the European standard for linear joint seals and is accepted as a national standard in CEN member states including the UK. Refer to page 22 for details on our B1 Fire Foam.
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APPENDICES: Polyurethane Foams
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