By Abhijit Phadke
Fire Retardant plywood is a type of plywood which is treated with special fire retardant chemicals at the time of manufacture, so that it becomes better at resisting fires. It is also known as FR grade plywood.
It is commonly used in public places, where the risk of fire has to be reduced such as for making the woodwork in the kitchens of large restaurants, or for the interior woodwork done in public theatres and halls, and the wood used in the railway compartments of our trains. It can also be used in homes and offices, for car interiors, and any other such places where the risk and spread of fire has to be reduced.
The Indian quality standards for manufacture of FR grade fire resistant plywood are specified in document IS:5509. The rate of burning of the plywood should be more than 20 minutes, the time taken for flames to penetrate the plywood has to be more than 30 minutes.
Chemicals such as diammonium hydrogen phosphate, are used to make fire retardent plywood. The addition of fireproofing chemicals, gives the plywood better fire proofing qualities such as,
1. Lesser tendency of spark and ignite.
2. Slow burning, having a decreased tendency of the fire to spread over the surface of the plywood.
3. Low flammability and lesser smoke generation.
4. Higher flame penetration time.
The usage of FR grade plywood for making home furniture is quite limited, however for the discerning customers, for whom cost is not a major concern, and who want to reduce the chances of fires in their homes, FR grade plywood can be a good choice. Other than the additional fire-retardent properties of FR grade plywood, all other characteristics of FR grade plywood are more or less similar to the regular plywood used that is used for making home furniture.
The sizes and thicknesses of fire retardant plywood are same as those for the commercial MR grade and the Exterior BWR grade types of plywood. Thickness usually ranges from 4 mm to 18 mm, while standard size sheets such as 8' x 4' are commonly used.