To protect human body from radiant heat, special type of protective clothing is necessary. There are different types of radiant heat protective clothing in the market but aluminized finished radiant heat protective clothing is considered as the best one. Radiant heat protective capability of the clothing is more dependent on the method of aluminized finishing. Smooth aluminized finished clothing radiates more heat and light than other type of finished fabrics, hence its radiant heat protective capability is better. It should be mentioned here that if the smoothness of the aluminized finished clothing is reduced or the clothing surface becomes dirty then the radiant heat protection capacity of aluminized finished clothing is reduced. Hence aluminized finished clothing is again finished with special type of resin coating very lightly, as a result increases abrasion resistance power of the clothing, Soil less and easily cleaned. It is experimentally proved that when aluminized finished clothing, is subjected to radiant heat together with other type of radiant heat resistant clothing, temperature generation on surface of the aluminized finished fabric is half of the other type of finished clothing at still air, and in case or running air, temperature generation on aluminized finished clothing is further reduced.
Beside the method of aluminized finish, fabric density is also related with radiant heat resistant property. Keeping the fabric weight, fiber composition and aluminized finishing method constant and only varying fabric density, lower density fabric shows better radiant heat resistant property than higher density fabric. The reason behind such result is that the lower density fabric contains more trapped air than higher density fabric. Thermal conductivity of trapped (Still) air is lower, hence lower density fabric shows better performance in radiant heat.Aluminized finished clothing shows good If radiant heat protective clothing resistant property but poor convective heat resistant property. If radiant heat protective clothing comes in contact to flame, as in case of a fire fighter clothing is not so good, but as clothing for a furnace man is good.
Fabric structure of the aluminized finished clothing is also related with radiant heat resistant property. Fabric may be woven, knitted or felted. Needle felted fabric shows better If radiant heat protective clothing resistant property. The reasons behind such result is that in case of woven and knitted fabrics, radiant heat, and conductive heat can easily pass through the trapped still air inside those fabrics but in case of felted fabrics the fibers in the fabric is arranged in scattered way hence radiant and conductive heat can’t easily pass through.
Presence of moisture in the radiant heat protective clothing has also relation with the radiant heat protective property. If presence of moisture increases in the radiant heat protective clothing, then the radiant heat protective performance is reduced.
Radiant heat protective clothing for fire fighters suit
Fire fighters suit should be made from three ply fabric. The outer ply fabric should be flame retardant, middle ply fabric should be vapor barrier and inner ply fabric should be thermal barrier. Outer layer fabric may be made from aramid fiber, blend of aramid and novoloid fiber or FR cotton As a outer layer fabric all the mentioned three types of fabric becomes embrittled within 10 seconds in contact to flame but the blended fabric of aramid and novoloid fibers are less brittle in such condition. Fire fighter suit made of above mentioned three types of outer ply fabric, if used during fire fighting; the wearer may be injured when in contact to flame for 28 to 50 seconds. The inner layer fabric is made of aramid fiber is not damaged in such situation. The middle laver fabric protects the user from the vapor and harmful chemicals fume when engaged in fitting against fire, but later may be sick due to the action of self sweating and vapor. For that reason the European fire fighters suit is made without the middle layer fabric.
As suitable clothing for fire fighter, three ply woolen fabrics may be used. The outer ply fabric may be made of wool serge which is fine but densely woven. The middle layer fabric is coarse and brushed woolen, works as heat resistant. The inner layer fabric works as lining made of light weight cotton fabric. As a fire fighter clothing, the effectiveness of the clothing is related to thickness of the clothing. Higher the thickness of the clothing betters the effectiveness of the clothing as fire fighter suit. It should be kept in mind that excessive thickness of the clothing will be none comfortable for the user due to heavy weight of the suit.
Fire fighter suit has been tested made from 56 types of fibers for their performance of fighting against fire. The fabrics were made from cotton, mixture of different cellulose fiber, aramid, wool, lather, asbestos, glass and ceramic etc. As a fire fighter suit, effectiveness of the clothing is more dependent on thickness of clothing than the fiber type.