What do you mean by special garments. Explain it with minimum 10 examples.
Ans:In the modern world, to perform risky work, it is necessary to wear special garments. It is especially used in risky environment. Because it is responsibility of the employers to protect their employees from any harmful effect during working at any risky environment.
The garments are used for protection of human body or life during working at any risky environment is called protective clothing or special garments.
Some special garments:
1. Heat and flame resistance clothing.
2. Protective clothing for radiant heat.
3. Fire fighter clothing.
4. Armed force clothing.
5. Protective clothing for space shuttle.
6. Clothing for coal miners.
7. Chemical resistance clothing.
8. Racing clothing.
9. Driving clothing.
10. Swimming clothing.
(b) Write down the objects of special garments.
1. To protect the employees body and life from the risky environment.
2. To protect human body from harmful effect of heat, flame and radiation.
3. To perform risky work.
4. It ensures proper working condition in risky operation.
5. It resistant heat and flame.
(c) Give the technical specification of racing driving cloth.
Ans: Special types of clothing are needed for the racing drivers. Blend of glass fibre and wool are used to spur the yarn and this yarn is used to weave the fabric of special construction. To spin the yarn β glass fibre is blended with wool fibers. The detail a Fabric SOP specification is given below:
Outer layer fabric: 85/15--wool/glass fiber
1. Structure: 2/2 twill
2. Mass (g/m2): 350 (gm/m2)
3. Yarn/cm: for warp 17.3 and weft 15.7
4. Yarn linear density: R 80Tx/2 all wool
5. Alternative arrangement: R 94 Tex/2, 70/30 wool/glass
Inner layer fabric: all wool knitted.
1. Structure: 22 rib with successive tucks.
2. Mass (gm/m2): 175
3. Loop length: 0.6 cm
4. Yarn linear density: R 44 tex/2
2. (a) Describe the heat & flame resistance clothing.
Ans: The people working in the steel mill, moulding factory, welding factory, glass item manufacturing factory etc. have to face heat and flame everyday. So, to protect their body heat and flame.
Human body and skin is heat sensitive. If human body is subjected to 45°c, he/she feels burning effect and 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/her.
If it is necessary to work at very high temperature for longer period, then the clothing should be of higher thickness. Because higher the thickness of clothing, lower compactness of the fabric, higher the heat resistant property of the cloth.
If it is necessary to work at a high temperature for short time then thicker fabric with more weight of industrial gloves, which shows good thermal resistant at 270° c for short period of time.
Molten iron, aluminum and magnesium splinter if drops on cloth, the clothing should be able to protect the human body from any damage. If the clothing made from very heavy and thick woolen fabric.
Protective clothing made of 540 gm/m2 thick woolen fabric can protect human body and if 350 ml molten iron, steel brass or copper fall on clothing then fabric weight should be 270-350 gm/m2 woolen fabric is sufficient. For this purpose, woolen fabric should be knitted structure as because knitted fabric shows better performance than woven fabric.
As per protection, length of time the following four types of fabric are listed below as per merits.
● Zirpro wool
●85/15 Zirpro wool/glass fiber
● Aramide fiber
● Fire resistance cotton (FR cotton).
(b) What is zirpro wool & zirpro finish?
Ans: Zirpro finish: To increase on woolen fibre, mix compound of titanium and zirconium is used for finishing wool fiber is called zirpro finish.
Zirpro wool: When zirpro finish is done on woolen fabric then the finished fabric is called zirpro wool.
(c) What types of fibers are suitable for making heat and flame resistance cloth as per merits?
Ans: The following fibers are suitable for making heat and flame resistance cloth as per merits.
● Zirpro wool
● Zirpro wool/glass fiber
● Aramide fiber
● Fire resistance cotton (FR cotton).
5) (a) Describe the loss of heat through clothing by radiation method.
Ans: Heat radiation means infrared radiation or microwave radiation. All the materials take part in radiation. Heat loss by radiation method can be expressed by the following theory:
Where, E= amount of heat energy loss
T= Temperature °k
e= Emissivity of body
The value of ‘e’ depends on the surface of the body and due to variation of color of the same body.
(b) Mention the factors which are dependent on heat loss and gain.
Ans: The following factors which are dependent on heat loss and gain. They are:
1. Temperature of the body
2. Surrounding temperature of the body
3. Emissivity of different materials.
6. (a) What is breathable fabric?
Ans: Breathable fabric is a fabric form which water molecules can not pass through but water molecules as vapor form can pass through special property of this type of fabric are called breathable fabric.
(b) Write down the problemable reasons for feeling discomfort during clothed situation.
Ans: When we are clothing, we can not expect discomfort due to that clothing. But in reality sometimes discomfort may occur due to some reasons. The problemable reasons for feeling discomfort during clothed situation are-
1. Due to weight or pressure of the clothing on the body or skin. Specially if the clothing pressure on the body or skin surface reaches heat in diatolic blood pressure which is 80 mm mercury or 120 g/cm2.
2. During cloth situation sweating occurs especially if sweating wets two third portion of body skin surface.
3. If capability of constant body core temperature is failed in only weather or in any physical activity level.
(c) Draw a table for type of work, rate of work, equivalent work evaporation for different activity level of human.
Ans: At different activity level of human, the work don is expressed as watt in the beneath table.
From the above mentioned table it was seen that the heat generation by human body varies depending on physical activity level. If physical heat generation is higher than heat loss also higher to maintain constant body core temperature. More that loss by human body means heat loss by sweating and moisture increase. To loss body heat as moisture. Design of clothing should be made carefully so that discomfort does not arise during clothed situation.
· To avoid such problem, special type of fabric has been recently developed through which water molecules can not pass through but water molecules as vapor form can pass through special property of this type of fabric are called breathable fabric.
7. (a) Describe the different types of breathable fabrics.
Ans: Breathable fabrics are mainly three types which are as follows:
1. Cotton ventile: It is the oldest types of breathable fabrics very compactly woven and finished. When the fabric becomes wet the cotton fibers swells, as a results, fabric becomes more compact hence water molecules con not pass through the clothing but water molecules in vapor form can easily pass through.
2. Cotton fabric with micro holes: It is special type of coated fabric. The coating contains very fine holes through which water molecules can not pass through but water molecules as vapor form can easily pass through Gortex is an example of this class of special fabric.
3. Hydrophilic film coated fabric: The fabric is coated with hydrophilic film. These films absorbs vapor from one side and passes the absorbed vapor in other side of the fabric bt water molecules can not pass through the film coating.
The polymer coating i.e polymer solution contains certain iso cyanate and special polymerization system is used.
(b) Describe a test method of breathablity of a fabric.
Ans: To asses the breathability o f clothing, different method of testing can be employed and results ma be very depends on thet method. A test method is described to test breathability, the quality of clothing.
A glass of water keeping 5 mm empty from top and should be weighted first for the weight of water only. Then cover the top side of the glasss by the experimental breathable clothing. At this moment, maintain 35°c temperature at the water of the glass. Then contain mild air flow on the clothing. During the test process, water from glass will evaporate and create vapor pressure on the breathable fabric. Due to lower moisture in the atmosphere (std RH 65% & temperature 20°c) the vapor from the in side the glass will pass through the breathable fabric. As a result, weight of water in the glass will be reduced. Again measure the weight of the water in the glass after 24hours by using different weight of the water in the glass. By this process breathability quality of clothing could be determined.
Engr. Kh. Mashiur Rahman Email: email@example.com