The people working in the steel mill, molding factory, welding factory, glass item manufacturing factory etc. have to face enough heat and flame every day. Hence their life risk is higher for save need to Heat and flame resistant clothing and save their body and life from the risk of flame and heat, it is necessary to provide them flame and heat resistant work wear. Human body and skin is heat sensitive. If human skin is subjected to 45°C, he/she feels burning effect and at 72°C, burning occurs in the skin, and blister is formed in the skin. If flame and heat resistant work-wear is worn, under such risky condition, gets some time to save him.
Why need to Heat and flame resistant clothing
If it is necessary to work at very high temperature for longer period, the clothing used should be of higher thickness and very compactly woven, Because, higher the thickness of clothing lower the compactness of the fabric, higher the heat resistant property of the clothing, because lower density of clothing means higher volume of still air. Still air shows better heat resistant property. Higher the still air in a fabric, higher the heat resistant property of that fabric. There is a limit up to which still air can retain by a fabric. If fabric density is very low when still air can’t retain by the fabric, then that fabric shows lower heat resistant property.
If it is necessary to work at higher temperature for short time then thicker fabric with more weight shows better heat resistant property. For example in case of industrial gloves thickness weight and resiliency is important. Gloves made of jersey wool fabric having pile fibers shows good thermal resistance at 270°C for short period of time.
Molten iron, aluminum and magnesium splinter if drops on clothing, the clothing should be able to protect the human body from any damage. In this situation, clothing made of very heavy and thick woolen fabric works satisfactorily. Protective clothing made of 540 grams per square meter thick woolen fabric can protect human body if 350 ml. molten iron, steel, brass, or copper falls on clothing. To protect human body from molten splinter of aluminum or magnesium, protective clothing made of 270 to 350 grams per square meter woolen fabric is sufficient. For this purpose, the woolen fabric should be knitted structure as because knit structure shows better performance than woven structure.
Clothing made of zirpro woolen fabric and caliban finished cotton fabric can protect human body from molten splinter of aluminum. Clothing made of aluminized finished fabric also shows satisfactory performance but the surface of the fabric must be smooth so that molten splinter can’t sticks with the fabric surface.
At clothed situation, time takes to feel burning on the body or to form blister on the skin due to flame contact, is considered as flame retardency property of the clothing. Higher the safe protection time better the flame retardant clothing made of zirpro wool, aramid, glass and FR cotton fabric subjected at 1200°C and found that to form blister on the skin time takes more in case of clothing made of zirpro wool. That means protective clothing made of zirpro wool works better against flame contact than the others. As per protection length of time, the above mentioned four types of fabrics are listed as per merit;
- Zirpro wool
- 85/15 zirpro wool/glass fibre
- Aramid fiber
- FR Cotton
Experimentally it is also found that flame protective clothing made of two ply zirpro wool fabric, the outer ply twill fabric of 290 grams per square meter and inner ply rib fabric of 230 grams per square meter shows longer time flame retardancy than the 552 grams per square meter single ply zirpro wool fabric. In case of flame protective clothing two ply fabric shows better performance than the single ply heavier fabric as because in case of two ply fabric, entrapped still air between two ply shows better thermal resistance, When zirpro finish is done on woolen fabric then the finished fabric is called zirpro wool. To increase flame retardancy property on woolen fibre, mix compound of titanium and zirconium is used for finishing wool fabric is called zirpro finish.