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International Conference on Advancements and Futuristic Trends in Mechanical and Materials Engineering (October 5-7, 2012)

Punjab Technical University, Jalandhar-Kapurthala Highway, Kapurthala, Punjab-144601 (INDIA) 7

HUMIDITY AND TEMPERATURE IN TEXTILE INDUSTRIES

Devanand Uttam*

Department of Textile Engineering, Punjab Technical University, G. Z. S. Campus, Bathinda, Punjab, India

* Corresponding author e-mail:- d_a_uttam@ yahoo.co.in

ABSTRACT

Relative humidity and temperature are found to play a very vital role in the successful processing of material in a

textile mill. These are essential in order to maintain product quality and reduce imperfections. Any imbalance in

humidity and temperature in textile manufacturing and storage facilities can have many serious implications in

moisture regain, static charge generation, fibre/yarn/fabric’s strength, product weight, dust in environment and

comfortability to workmen. Both factors have a tremendous effect on the smooth flow of the fibres through different

machines. The ideal conditions for the same material in different sections differ slightly. Knowledge of humidity

and temperarature, its role, measuremement and maintaining systems are very helpful in successful processing of textile material as well as reduction in health hazards in textile mills. In this paper, all above aspects are covered.

Keywords: Atmospheric conditions, humidity, relative humidity, humidifier, temperature.

1. Introduction

The atmospheric conditions with respect to

temperature and humidity play very important part in

the manufacturing process of textile yarns and

fabrics. Temperature alone does not have a great

effect on the fibres [1]. However the temperature

dictates the amount of moisture the air will hold in

suspension and, therefore, temperature and humidity

must be considered together. The properties like

dimensions, weight, tensile strength, elastic recovery,

electrical resistance, rigidity etc. of all textile fibre

whether natural or synthetic are influenced by

moisture in the fibre. Different classes of fibres

namely vegetable, protein or animal and manmade

are found to require different degrees of relative

humidity and temperature [2]. Both the factors have

a tremendous effect on the smooth flow of the fibres

through different machines. The ideal conditions for

the same material in different sections differ slightly. Failure to maintain these conditions result in several

hazards such as:

i. static charge generation due to friction,

ii. to much of fly in the atmosphere,

iii. chocks in machines,

iv. lap up on rollers, and

v. sometimes breaking of fibres.

2 Humidity

Humidity is dampness or moisture, on its

association with spinning and weaving relates to the

condition of the atmosphere of the rooms in which

spinning/weaving operations are in progress. This

moist condition of the air involves two factors: the

actual amount of moisture and the relative amount.

Strange to say, the actual amount of moisture in a

spinning and/or weaving room is not the deciding

factor. The definition of terms related to humidity are as under [3]:

Humidity is a term used to describe the amount of

moisture present in the atmosphere. This can be

described in terms of absolute humidity and relative

humidity.

Absolute Humidity is the weight of water present in a

unit volume of moist air. It is the actual density of

water vapour in the atmosphere and it can be

expressed in terms g/m3 or grains/foot

3.

Where, W1 - Weight of water present in the air

V - Volume of the air

Relative Humidity is the ratio of the actual vapour

pressure to the saturated vapour pressure at the same

temperature.

Where, Pa - Actual vapour pressure

Ps - Saturated vapour pressure

3 Influence of Atmospheric Conditions

Many properties of textile materials vary

considerably with moisture regain, which in turn is

affected by the ambient temparature and relative



humidity (RH). If a dry textile material is placed in a

room with a particular set of ambient conditions, it

absorbs moisture and in course of time, attains an

equilibrium. Practically, all the textile fibres show

increased pliability or spinning capacity and greater

resistance to static electrical influence with increase

in amount of moisture.

3.1 Impact of temperature

Temperature plays an important role in successful

processing of material in the textile industries. Different fibres require different degree of

temperature for better performance. Mechanical

properties of fibres and yarns also depend on the

surrounding temperature conditions to which these

are exposed during the textile process.

Due to high heat dissipation from spinning as well

as weaving and knitting equipment there is a

significant increase in temperature conditions

particularly in the vicinity of the machinery and their

driving motors. The natural wax covering cotton

fibres softens at these raised temperature conditions, thereby adversely affecting the lubricating property

of wax for controlling static and dynamic friction.

Increase in temperature beyond the design limit also

reduces the relative humidity condition near the

processing elements of the machinery. Hence textile

air-engineering design has to take care of controlled

air flow within the textile machinery for dissipating

heat generated at the source and it is customary to

carry the waste heat along with the return air to the

return air trench. The quantity of return air going to

exhaust or recirculation is regulated for controlling

the inside design conditions. Modern spinning equipment is designed to operate at high spindle

speed. However high ambient temperature always

tends to curtail the speed limit of operation.

Moreover, the sophisticated electronic controls in

modern textile machinery also require that inside

temperature in the department should not exceed

33°C or so.

It is also necessary to limit the range of

temperature to which the textile machinery is

exposed, since the structure of the machinery

containing many steel and aluminum parts which expand at different rates with temperature rise (due to

difference in co-efficient of thermal expansion) will

be subjected to mechanical stress.

Hence, along with maintenance of stable relative

humidity conditions recommended for different

textile processes, it is also desirable to maintain the

temperature level within a range, without fluctuation.

Generally one common source of heat supply from a

boiler house is used in textile mills. The heat is

distributed by means of any convenient heat carrier

to separate heated buildings as: water heating, steam

heating, air heating [4]

3.2 Impact of humidity

3.2.1 Influence of humidity on fibre properties

Some of the important properties of a textile

fibre are closely related to its behavior in various

atmospheric conditions. Most fibres are hygroscopic

in nature, that is, they are able to absorb water vapour

from a moist atmosphere and desorbs or loss water in

a dry atmosphere. The changes of moisture in the

atmosphere results in change of moisture in the

material and this will change in the physical

properties of the material such as dimensions, tensile

strength elastic recovery, elastic resistance, rigidity

etc. [3]. For example:

a. Cotton absorbs moisture more rapidly when

exposed to high humidity and a result, weight

and strength of the material increased and other

properties will be changed. b. Manmade regenerated fibres like viscose, acetate

etc show a reduction in strength with increase

in moisture content and correspondingly increase

in elongation.

c. Man made synthetic fibres such as polyester and

nylon will not be affected much with moisture

because they are not fully hygroscopic.

d. However wool shows a slight decrease in

strength with increase in the amount of moisture.

3.2.2 Influence of humidity on processing

Textile processing is also influenced with the changes in the amount of moisture in the atmospheric

conditions [3]. Under ideal humidity condition, the

following advantages are realized during processing.

i. Reduction in the generation of static charges.

ii. Reduction in fibre damage during processing

iii. Material is more easily workable due to

increased pliability

iv. Reduction in dust and fly.

v. Allows for the retention of moisture already

present in the material

vi. Permit greater bodily comfort to the workers.

4. Measurement of Atmospheric Conditions

The instrument used in the determination of

humidity are known as Hygrometers or

Psychrometers [3, 5]. In the textile mills and testing

laboratories the following instruments are mainly

used:

i. Wet and dry bulb hygrometer (plain or aspiration

psychrometer)

ii. Hair hygrometer or thermohygrograph

iii. Electrolytic hygrometer

Wet and dry bulb hygrometers (Fig. 1) are

popular in textile mills. It consist two identical

thermometers. Bulb of one thermometer is covered

by muslin sleeve which is dipped into a reservoir of



distilled water. This is known as wet bulb

thermometer and it give wet bulb temperature.

Second thermometer which bulb is uncovered gives

dry bulb temperature.

The difference between these two temperatures

is noted and the hygrometric table is referred for the

dry bulb temperature in one column and the

corresponding difference of the wet bulb indicates

the percentage relative humidity. For example:

Dry bulb temperature: 88 ºF

Wet bulb temperature: 78 ºF

Difference of temperatures: 10 ºF

RH% (from the table): 58 %

Fig. 1: Wet and dry bulb hygrometer

(adopted from the ref. no. 3)

5. Environmental Conditions in Various Departments

Temperature and humidity for different

departments are mention in the Table 1.[3,2.6,7].

5.1 Mixing and blow room

One of the objects of mixing is to allow the fibres

to regain their original form and proper humidity

after they are released from the heavy stresses and

strains while in the bale form. For this, the bales are

left in open state for about 24 hours in a chamber

where adequate humidity is maintained [2].

In blow room if more humidity in the department the clinging becomes more and thus the cleaning

efficiency drops. If humidity is sufficient, the fibres

gain strength and thus damage to fibre is minimized.

In order to attain such conditions at all times, a blow

room is equipped with over head steam pipes

adjustable for dry and wet steam, humidification fans

and duct lines capable of injecting into the

department, dry or humidified hot or cold air as per

requirements.

Table 1 Temperature and humidity for different

departments

S.

No

Department

Relative

humidity

(%)

Temp.

(º C)

1 Mixing room 60-70 27-33

2 Blow room, Carding

and Drawing Section

50-60 27-35

3 Combing 55-65 27-35

4 Speed frame 50-60 27-35

5 Ring spinning Section 55-65 30-35

6 Rotor spinning 60-70 30-35

7 Winding / Warping 60-70 27-33

8 Sizing 70-80 25-30

9 Weaving 77-82 25-30

10 Standard Testing

Environment 65 2 20 ± 2

11 Standard Testing

Environment for

tropical and subtropical

regions like India

65 2 27 ± 2

5.2 Carding and other sections

Wide fluctuations in humidity and temperature in carding cause either to much of fly in the department,

web sagging, web flying or lapping on doffer etc., as

in this state, the material becomes quite sensitive to

temperature and humidity. In carding section no jet

steam nozzles are required, become live steam is

detrimental to card fillet wiring. Rusty wire points

spoil carding quality and weaken the fillet

foundation.

In drawing and combing section similar effect can

be seen. In speed frames and ring frame sections

lower humidity makes the material go dry and soft and encourage fly and static generation. End

breakages will excessive, and bobbin becomes soft

and bulging. Excessive humidity results in roller

lapping, undrafted ends and uneven drafting. All

these adversely affect the product quality.

5.3 Weaving and Knitting

Weaving rooms for cotton fabric making are

designed to maintain high relative humidity of 80% to 85% at the warp sheet level i.e. at 'loomsphere' as

high humidity helps to increase the abrasion

resistance of the warp. Whereas it would suffice to

maintain general humidity condition in the room at

around 65% R.H., Knitting operation also requires a

stable relative humidity condition at 55% ± 5% for

precise control of yarn tension. Hence it is important



to maintain stable relative humidity conditions within

the prescribed tolerance limits at all steps of textile

processing [4].

5.4 Seasonal Care

. The mill requires different manipulations in

different seasons to maintain humidity and

temperature. The direction of winds too has similar

effects. During summer in several places, the outside

weather is quit humid and it requires lot of skill and a

suitable plant to get desired temperature and relative

humidity. A dehumidification or refrigeration plant

might become quite necessary in order to avoid

raising of temperature beyond desired level. In

winter, the atmosphere goes dry at to attend required

humidity conditions initial heating of the department

become necessary. If the machine temperatures are

not raised, condensation occurs leading to rusting of

parts [2].

6. Maintaining Humidity and Temperature

6.1 Central humidification plants

Central Humidification plants are of masonry

type, the components of the plant housed inside a

civil room with brick wall and RCC slabs and usually

located adjacent to the department at strategic

locations based on the nature of the truss for the feasibility of layout of overhead ducting with

minimum length of travel and based on the ease of

connecting the underground Trenches with minimum

bends [8].

Fig. 2: Schematic diagram central humidification plants (adopted from ref. no. 09)

1. Fresh air damper 7. Supply air fan 13. Duct collector fan 2. Water pump 8. Manual control damper 14. Rotary air filter

3. Air straightner 9. Supply air duct 15. Extract air fan 4. Spay nozzle 10. Department (spg.,wvg etc.) 16. Exhaust air damper

5. Water drop eliminator 11.Return air duct 17.Return air damper 6. Washer air damper 12. Duct Collector 19. By-pass air damper

In the humidification plant (Fig. 2), the fresh air

enters from air damper (1) pass through air

straightener and spray nozzle where water is added in

the air. The water drops present in the air are

eliminated by water drop eliminator (5). The humid

or re-circulated air forced to department (10) through

the supply fan (7), manual control damper (8) and

supply air duct (9). The air return from the

department through the return air duct (11) with the

help of duct controller (12) and duct controller fan

(13). The return air having some dust, short fibres

etc. which are filtered by rotating air filter (14). The

filtered air extracted with the help of extracted air fan

(15) is thrown outside. This return air either re-enter

by return air damper (17) or by bypass air damper

(18).



6.2. Centrifugal spot humidifier (or water automiser)

For maintaining a sufficiently high humidity in

the mixing, winding and weaving sheds etc. a

“Centrifugal spot humidifier” is used (Fig. 3). The

water is so finally atomized that the drops are

completely evaporated and there is no need in the

arrangement of sewerage lines. This can be used for

textile industries in various departments such as

ginning, mixing, blow room, cone winding, yarn

conditioning, yarn packing and loom shed, etc. where

high humidity required [10].

6.3 Air conditioning

Air conditioning is the control of air temperature,

humidity, cleanliness and distribution of air.

Temperature control involves heating the air in

winter and cooling it in summer. Heat may be generated from a control heating plant using hot

water or steam as a heating medium. Cooling may be

caused by piping the coolant from a centralized

compressor plant to local areas where air is run

through the coil. Self contained air conditioners may

be installed directly in the room to be cooled.

Fig. 3: Schematic diagram of “Centrifugal spot

mini humidifier” (adopted from the ref. no. 10)

Fig. 4: Schematic diagram of a standard air conditioner (adopted from the ref. no. 5)

1. Warm insulated valves (Inlet) 10. Chamber with filters (Section with filters) 15,16. Drop catchers 2, 5, 8. Chamber (Section) 11.Valve for air supply) 17. Air heaters

3, 6, 9. Valves 12.Outlet opening 4. By- Pass arrangement 13.Fan

7. Spray chamber 14. Supports

Humidity of the air is adjusted by adding moisture

to it in winter and by removing moisture from the

moist summer air. Air is cleaned of foreign materials

such as dust etc. by forcing air through a spray of

water, passing air through filters and electrostatic

precipitation. Air motion is achieved by proper

positioning of incoming air ducts and exhaust out

lets. Odors and Bacteria in air are removed by

passing air over chemicals. In textile mills, there is necessary to create an

artificial climate (i.e. certain temperature, humidity

and mobility of air) by means of ventilation and

humidifying units. The air conditioning system

comprises installation for heating, cooling, cleaning,

humidifying and drying the air. It is equipped with

automatic control devices [5].

It consists of sections arranged in consecutive

order and performing different functions (Fig. 4).

Outside air flows through worm insulated valves (1)

into the chamber (2) and further through the air

heater (17) into the section (5).



In summer the passage through the air heaters is

closed and the air flows into the section (5) through

the valve (3) and the by-pass canal (4).Moreover,

through the valve (6) there is an air intake from the

ambient air of the shop into the section (5) for its

further cleaning in the conditioner.Mixed air passes

from section (5) into the spray chamber (7) where the

air is humidified, dried, cooled, and heated

depending on its condition in the shop. Passing

through the water screen in the spray chamber (7),

the air is cleaned from dust and charged with

negative ions. At the entry and exit from the spray

chamber there are drop catcher (15) & (16) provided.

Further from spraying section air flows into the

chamber (8) where the air coming from the shop is

subjected to a second recirculation through the valve

(9). There from the air enters the section (10) with

filters for its dedusting. Next from the chamber (10) the air passes via the connecting section (2’) in the

second heating block and finally it supplied into the

shop through the outlet opening (12) of the fan (13).

The air supply is adjusted by valves (11)

7. Conclusions In textile industry, atmospheric conditions with

respect to temperature and humidity play very

important role in properties of textile fibres, product

quality and manufacturing process of yarns and

fabrics. Relative humidity will improve regain in the

material, maintain yarn strength, reduced static

charge build-up, maintain product weight, reduce fly

and dust, provide cooling etc. Mechanical properties

of fibres and yarns depend on the surrounding

temperature conditions to which these are exposed

during the textile process. Different fibres require

different degree of temperature for better

performance. For maintaining desire humidity and

temperature in the ambient atmosphere, centralized

air conditioning system is more suitable than other

systems as it control humidity, temperature,

cleanliness and distribution of air.

8 References

1. Humidification in Textile Mill, http://www.

cottonyarnmarket.net/OASMTP/HUMIDIFICATION%20IN

%20TEXTILE%20MILL.pdf, Assessed on 25.06.12

2. Pattabhiram, T. K., Relative humidity (1997), Essential

Elements of Practical Cotton Spinning, Somaiya

Publications Pvt. Ltd. Mumbai, pp.189-195.

3. Angappan, P., Gopalakrishan, R. (1993), Moisture relation

and Identification of fibres, Publisher S.S.M.I.T.T Staff and

Student’s Co-op. Stores Ltd., Komarapalayam, Forth

Edition, pp.1-37.

4. Roy M.M, Humidification for textile, Air Conditioning and

Refrigegeration Journal, http:// www.ishrae.in /journals_

20042005/2005jan/article 02. html, Assessed on 24.06.12

5. Onivov. E.(1981) Major recommendations on the

maintenance of buildings and operation of heating,

ventilating, humidifying and lighting systems in cotton

weaving mills, Hand book of cotton weaving, MIR

publication Moscow, pp.216-231.

6. Patel, S.P. Role of Humidity & Temperature and

Humidification Systems For modern Spiining Plant, NCUTE

Training Programme on Ring Spiining, Doubling and

Twisting, Textile & Engg. Institute, Ichalkaranji, pp.79-95.

7. Poddarji (1992), Humidification, ventilation and lighting,

Colourage, pp.67-68.

8. Central Humidification Plants, http://www. excelair. co.in

/centralhumidificationplant.html, Assessed on 28.06.12.

9. Schicht, H . H.(1983), Air Engineering: The application ofair

engineering in Textile mill, Textile Month, February,pp.43-

46.

10. http://www.tradeindia.com/fp6276/Centrifugal-Spot-

Humidifier-Unit.html, Assessed on 28.06.12.

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