186

CHAPTER 6

DESIGN AND DEVELOPMENT OF HOSPITAL BED LINEN

6.1 INTRODUCTION

The bed sheets used in hospitals are made of cotton or polyester

cotton blended fabrics, which seems to date from the past centuries. But these

hospital textiles need to ensure the comfort and hygienic level of the patient

and needs to be engineered with specific comfort properties. But no effort has

been made to make new textile materials that could help in reducing the

discomfort experienced by the patients.

This part of the research work aims at analyzing the comfort

characteristics of existing hospital bed linen and analyzing the biomechanics

of human body so as to understand the amount of heat and sweat to be

transferred by the clothing next to the skin. This chapter also analyses the

suitability of the lyocell fiber based single layered hospital textiles developed

and their effectiveness in ensuring the thermo physiological comfort

characteristics for the selected end use.

6.2 ANALYSIS OF EXISTING HOSPITAL BED LINEN

A questionnaire was prepared and survey carried out in various

hospitals to analyze about the type of mattresses and bed linen used in

hospitals. The existing hospital bed linens used in hospitals were collected

and analyzed for their comfort and hygienic properties.

187

Commercially used hospital bed linen, collected from various

hospitals were found to be made of 100% cotton yarn with count in the range

of 16s, 20

s, 30

sand 40

s Ne which are bleached or vat dyed in blue or green

color.

The yarn and fabric parameters are given in the Table 6.1.

Table 6.1 Yarn and Fabric parameters of hospital bed linen

S.No Fabric type Yarn

count

Ends

/cm

Picks

/cm

Fabric

weight g/m2

Fabric

thickness

(mm)

1 Cotton

Bleached

20 23.6 23.6 143 0.22

2 Cotton Bleached

Plain

30 48.8 25.2 138 0.19

3 Cotton Bleached

Twill

40 52 30 123 0.15

4 Cotton

Vat dyed -Blue

40 53.5 28.3 137 0.16

5 Cotton

Vat dyed -Green

16 7.08 5.11 208 0.40

The Hospital bed linen fabrics were analyzed for their comfort and

moisture management properties using standard test methods and are listed in

the Table 6.2.

188

Table 6. 2 Comfort properties of hospital bed linen

Fri

ctio

na

l

Fact

or

(F/N

)

S.N

o

Air

Per

mea

bil

ity

(cm

3/c

m2/s

)

Th

erm

al

con

du

ctiv

ity

(w/m

/k)

Wate

r

vap

ou

rper

mea

bil

ity

(g/m

2/2

4 h

rs)

Ab

sorp

tion

(sec

)

Sp

read

ing a

rea

(cm

2)

static dynamic

Ver

tica

l w

ick

ing

-

(warp

)

(cm

)

Ver

tica

l w

ick

ing

-

(Wef

t)

(cm

)

1 56.61 0.015 1600 0.9 3.51 1.78 1.15 0.43 4.50

2 13.39 0.015 1600 1.35 3.83 1.47 0.91 0.49 4.80

3 11.22 0.011 1600 2.52 3.31 0.77 0.62 5.00 5.50

4 6.387 0.015 2044.44 13.0 0.75 1.26 0.82 7.30 7.30

5 62.275 0.031 1777.78 0.7 1.00 1.56 1.18 4.21 4.08

6.2.1 Air Permeability of Hospital bed linen

Figure 6.1 shows the air permeability values of the five commercially

available hospital bed linen samples. Fabrics made of courser count yarn have

higher air permeability when compared to finer fabrics with higher ends and

picks per inch. This may be due to the lower porosity of fabrics with higher

cover factor. Twill woven cotton fabrics made of 40s count yarn has least air

permeability whereas the coarser fabric made of 16s count yarn has higher air

permeability.

0

10

20

30

40

50

60

70

cm

3/c

m2/s

1 2 3 4 5

20s 30s 40s 40s(b) 16s

Air Permeability

Figure 6.1 Air Permeability of hospital bed linen

189

6.2.2 Thermal conductivity of Hospital bed linen

Thermal properties of textile materials especially thermal conductivity

have always been the major concern, when the comfort properties of hospital

textiles are concerned. Figure 6.2 shows the test results of thermal

conductivity, which is a measure of the amount of heat transferred through

fabric in w/m2/k for the five different hospital bed linen fabrics. Among the

hospital bed linens, thermal conductivity is high for 16s count hospital bed

linen and least for 40s twill woven fabrics. Fabrics with courser count conduct

heat effectively when compared to finer fabrics. This may be due to the higher

porosity of courser fabrics.

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

w/m

/k

1 2 3 4 5

20s 30s 40s 40s(b) 16s

Thermal conductivity

Figure 6.2 Thermal conductivity of hospital bed linen

6.2.3 Water Absorbency of Hospital bed linen

Figure 6.3 shows the water absorbing capability of hospital bed

linen fabrics in terms of the time taken to completely absorb one drop of

water by the surface of the fabric. The courser fabric made of 16s count yarn

absorbes water very fast compared to other fabrics and the vat dyed blue

fabric made of 40s count yarn takes maximum time for absorbing water. Other

hospital bed linens exhibited moderately slower water absorbing property.

190

0

2

4

6

8

10

12

14

Sec

1 2 3 4 5

20s 30s 40s 40s(b) 16s

Water absorption

Figure 6.3 Water absorbency of hospital bed linen

6.2.4 Water spreading area of Hospital bed linen

Figure 6.4 shows the extent to which a water drop spreads on the

fabric which is an indicator of its drying rate. Amongst the hospital bed linen

fabrics, bed linen made of 20s, 30

s and 40

s cotton fabrics showed maximum

spreading area compared to other fabrics.

Figure 6.4 Water spreading behavior of hospital bed linen

191

6.2.5 Frictional Factor of Hospital bed linen

The static and dynamic frictional factor is measured for all hospital

bed linen and is shown in Figure.6.5. Among the hospital bed linen fabrics,

40s count cotton bed linen has less friction due to its finer yarn count and

smooth fabric surface because of twill weave structure.

Figure 6.5 Frictional factor of hospital bed linen

6.2.6 Water vapour Permeability of Hospital bed linen

Moisture vapour transfer is the ability of the fabric to transfer

perspiration in the form of moisture vapour through it. It is measured in terms

of the amount of water vapour passing through a square meter of fabric per

day. A fabric with low moisture vapour transfer is unable to transfer sufficient

moisture, leading to sweat accumulation and hence discomfort.The moisture

vapour transfer ability of the existing hospital bed linen is shown in the figure

6.6. The vat dyed blue fabric made of 40s count yarn has maximum water

vapour permeability and other fabrics exhibit comparatively equal water

vapour permeability.

192

0

500

1000

1500

2000

2500

g/m

2/d

ay

1 2 3 4 5

20s 30s 40s 40s(b) 16s

Water vapor permeability

Figure 6.6 Water vapour permeability of hospital bed linen

As far as wickability is concerned, the finer fabrics have maximum

wicking tendency both in warp and weft direction.

6.3 ANALYSIS ON THE PHYSIOLOGY OF HUMAN BODY

The heat and moisture transmission behavior of a fabric plays a

very important role in maintaining thermo-physiological comfort of the body.

The human body continuously generates heat by its metabolic processes. The

heat is lost from the surface of the body by convection, radiation, evaporation

and perspiration. In a steady-state situation, the heat produced by the body is

balanced by the heat lost to the environment by maintaining the body core

temperature around 37ºC.

A person can live comfortably only in a very narrow thermal

environment from 26°C to 30°C without wearing clothing. With clothing,

human beings can live and perform various physical activities comfortably in

a wide range of thermal environments from -40 ºC to 40ºC. So clothing plays

an important role in providing thermal protection for the human body and

creates a comfortable thermal microclimate. The amount of heat and sweat

generated by a sleeping person and a person confined to wheel chair is given

in the Table 6.3.

193

Table 6.3 Range of metabolic heat generation for various activities

Activities Metabolic heat generation

Sleeping 35 W/m2

Seated Quietly 55-65 W/m2

Standing 65-75 W/m2

Normal activities 80 W/m2

Heat generation

Body temperature at rest 37 ºC

Energy required for basic activity 40 kcal/hr/m2

Metabolic rate of a sleeping person 0.7 met(1 met is 58.15 W/m² or 50 k

cal/m2.h)

Heat disscipated through evapouration 50 .12 k cal/m2.h

Heat disscipated through clothing 38 k cal/m2.h

Insulation of air 0.14 m2 Ch/k cal

Insulation of clothing 0.18 m2 Ch/k cal

Total energy radiated by an adult male 2000k cal/day

Total surface area of female thermal

manikin.

1.8 m²

Sweat generation

Perspiration in unstressed condition for

resting person

15g/m2/h (or) 360g/m

2/day (or)

720 g/day/person

Perspiration in hot condition 100 g/m2.h

Heat disscipated through evapouration 50 .12 k cal/m2.h

The heat loss for every ml of water

evapourated

0.58 kcal

The maximum rate of sweating in an

acclimatized adult.

5 ml/min or 2000ml/hr

The transversal moisture diffusion 100 to 150 ml per day per m² of skin

Sweat generation for low activity 500 ml/day

Sweat generation for high activity 2 l /day

1 clo 0.18 m2 Ch/k cal = 0.155m

2 C/w

194

6.3.1 Heat loss from human body

Heat is generated within the human body by the combustion of

food. The heat is lost from the body by

Conduction and convection - about 16%

Radiation - about 60%

Evapouration of moisture - about 12%

Exhaled air - about 12%

Evapouration prevails at high ambient temperatures. Conduction

and convection prevails at low ambient temperatures. Heat is liberated in a

rate maintaining the internal body temperature at 37oC.The total heat loss

from an adult at normal activity is approximately 118 W (2 Met) in a room

with temperatures between 19oC and 34

oC.

The metabolic heat generated and the amount of heat transferred

from a person to surrounding by conduction, convection, radiation,

evapouration and through exhaled air is listed for a person under the

conditions of sleeping, sitting idle and normal activity below.

Table 6.4 Heat transferred from a person to the surrounding

Heat transferred from a person to the surroundingActivity Metabolic

rate Conduction

or convection

(16%)

Radiation

(60%)

Evapouration

of Moisture

(12%)

Exhaled air

(12%)

40.71 w/m2 6.51 w/m

224.43 w/m

2 4.88 w/m

24.88 w/m

2

73 w 11.68 w 43.8 w 8.76 w 8.76 wSleeping

0.7 met 0.11 met 0.42 met 0.08 met 0.08 met

46 w/m2

13.6 w/m2

27.6 w/m2 5.52 w/m

2 5.52 w/m

2

85 w 13.6 w 51 w 10.2 w 10.2 wResting in bed

0.8 met 0.13 met 0.48 met 0.10 met 0.10 met

58 w/m2

9.28 w/m2

34.8 w/m2 6.96 w/m

2 6.96 w/m

2

104 w 16.64 w 62.4 w 12.48 w 12.48 wSeated

1 met 0.16 met 0.6 met 0.12 met 0.12 met

65.56 w/m2 10.49w/m

2 39.34 w/m

2 7.87w/m

27.87w/m

2

118 w 18.88w 70.80w 14.16w 14.16w

Normal

activity

2 met 0.32met 1.20met 0.12met 0.12met

195

In estimating the effect of convection on the cooling of the body, it is

combined with conduction.

6.3.1.1 Heat loss by Conduction

The basic heat transfer equation for conduction is

d

TT(kA

t

Q )coldhot (6.1)

Where, in this case, A would be the area of the human body (1.8

m2)and k the thermal conductivity of the air surrounding the body(5.7 x

10-5

cal/s/cmºc). Under normal conditions the heat conducted by a human body

is 10.5 watts which is not sufficient to transfer the entire heat from the body.

6.3.1.2 Heat loss by Radiation

The basic heat transfer equation for radiation is

)TT(Aet

Q 4

cold

4

hot (6.2)

where A is the area of the human body(1.8 m2) and e is the

emissivity of the skin. In this case the human skin is near ideal radiator in the

infra red range and has an emissivity value of 0.97.

= 5.67 x 10-8

watts/m2/k

4 (Stephen – Boltzmann constant)

T hot = 307°K, T cold = 296°K,

Under normal conditions the heat radiated by a human body is 133

watts, which is more than adequate to cool the body.

196

6.3.1.3 Heat loss by Evapouration

At higher ambient temperature (>37ºC), the heat transfer

mechanisms like radiation, conduction and convection transfers heat into the

body rather than out. Since there must be a net outward heat transfer, the only

mechanisms left under those conditions are the evapouration of perspiration

from the skin and the evapourative cooling from exhaled moisture. Even

when one is unaware of perspiration, physiology texts quote an amount of

about 600 grams per day of "insensate loss" of moisture from the skin.

The cooling effect of perspiration evapouration makes use of the

very large heat of vapourization of water. This heat of vapourization is 540

calories/gm at the boiling point, but is even larger, 580 cal/gm, at the normal

skin temperature.

watts17)S3600

hr1()

hr24

day1()

cal

J186.4()

gm

cal580()

day

gm600(

T

q (6.3)

As part of the physiological regulation of body temperature, the

skin will begin to sweat almost precisely at 37°C and the perspiration will

increase rapidly with increasing skin temperature. Guyton reports that a

normal maximum perspiration rate is about 1.5 liters/hour, but after 4 to 6

weeks of acclimatization in a tropical climate, it can reach 3.5 liters/hr. The

maximum rate corresponds to a maximum cooling power of almost 2.4

kilowatts.

The general energy balance equation is as follows,

M –W =C + R + E +C res +E res + S (6.4)

Where

M metabolic rate, W/m2

W mechanical power, W/m2

197

C convective heat loss from skin, W/m2

R radiation heat loss from skin, W/m2

E evapourative heat loss from skin, W/m2

C res Convective heat loss from respiration

E res evapourative heat loss from respiration

S rate of body heat storage

The left side of this equation is internal heat production and the

right side describes the sum of heat exchanges from the human body. For

normal activities, the mechanical power is negligible and can be made equal

to zero. Under thermal equilibrium conditions, body heat production is equal

to body heat loss. There is neither heat storage in the body, nor dissipation of

stored heat from the body. Hence all the heat generated has to be dissipated

through conduction, convection and radiation.

6.3.2 Heat transfer through clothing

The basic metabolic heat generated in a body is to be transferred

through clothing. Heat transfer through evapouration of sweat is governed by

the water vapour permeability of fabric. For a body covered with clothing, the

amount of heat transferred by convection, conduction and radiation are to be

dissipated by thermal conductivity of the fabric worn next to skin assisted by

heat transfer through air. Hence thermal conductivity, air permeability and

moisture vapour permeability of a fabric determines the ability of a fabric to

ensure thermal comfort.

Clothing convective and radiative heat exchanges R and C can be

determined in various ways.

1. Clothing convective and radiative heat exchanges R and C in

W m2are determined principaly by:

198

I

rCR (6.5)

Where,

I is the thermal insulation of clothing (m2 °C W

1),

t is the temperature gradient across the clothing layer (°C)

(normally skin to clothing surface)

2. For static conditions with no air motion, R+C is determined by:

T

osk

cla

ocl

cl

clsk1o2

I

II

f/I

II

I

II)CWm(CR (6.6)

Where

fcl is the clothing area factor (the ratio in surface area between

the outer clothing surface and the nude person’s surface

area; dimensionless),

tcl the clothing surface temperature,

to the ambient operative temperature (°C).

Icl intrinsic clothing insulation

Ia insulation of surface air layer

IT insulation of clothing with surface air layer (m2 °C W

1).

3. R+C can also be determined, as in ASHRAE standard by:

R+C (Wm2 °C

1)= Fcl (hc+hr) (tsk to) (6.7)

Where,

Fcl - the dimensionless clothing efficiency factor

hc - convective heat transfer coefficient (both in W m2 °C):

hr - radiative heat transfer coefficient (both in W m2 °C):

The dimension less clothing efficiency factor Fcl can be determined

by using the formula,

T

rc

T

a

clacl

a

clI

)hh/(1

I

I

f/II

IF (6.8)

199

The amount of heat radiated is likely to change with air movement

and body motion due to the increased convection in and on the surface of

clothing layers.

Heat transfer through evapouration of sweat is governed by the

water vapour permeability of fabric. Hence thermal conductivity, air

permeability and moisture vapour permeability of a fabric determines the

ability of a fabric to ensure thermal comfort. The amount of heat to be

transferred by the fabric through thermal conductivity and moisture vapour

permeability is given in the Table 6.5.

Table 6.5 Amount of heat to be transferred

Activity

Amount of heat

conducted through

fabric

Amount of moisture

vapour through fabric

Sleeping 30.94w/m2

173.45 g/ m2/ day

Resting in bed 41.20 w/m2

196.40 g/ m2/ day

Seated 44.08 w/m2

247.60 g/ m2/ day

Normal activity 49.83 w/m2

280.00 g/ m2/ day

From the above Table it can be observed that the amount of

moisture vapour to be transferred through the fabric ranges from173 to 280

g/ m2/ day where as the water vapour permeability of the single layered and

multi layered fabrics developed are more than 1600 g/ m2/ day which is more

than sufficient to transfer the moisture vapour. Hence all the fabrics

developed are capable of transferring the moisture.

To ensure thermal comfort, the metabolic heat generated must be

dissipated through the cloth by conduction, convection or radiation. The

regression equations for the convective heat transfer coefficients

200

(hc [W/ (m2 K)]) for natural convection, driven by the difference between the

mean skin temperatures corrected using the convective heat transfer area and

the air temperature, and the convective heat transfer coefficient for a human in

three different posture, when the difference in body and ambient temperature

is around 5°C, are given in the Table 6.6.

Table 6.6 Convective heat transfer coeffeicent of human body

S.No Activity Formula for

hc [W/ (m2 K)]

Convective heat transfer

coefficient W/(m2 K)

1 Standing (exposed to

atmosphere) hc = 1.183 T0:406

1.183(50.347

) 2.068

2 Chair Sitting (contact

with seat, chair back

and floor)

hc = 1.222 T0:299

1.222(50.299

) 1.977

3 Sleeping (floor

contact) hc = 0:881 T0:368

0.881(50.360

) 1.573

The heat to be transferred for a sleeping person is 1.573 W/ (m2 K)

whereas the heat transfer through all single and multi layered fabrics

(annexure 1) are not sufficient to transfer the heat. If supplemented with an air

circulation the amount of heat transferred could be improved.

6.4 COMPARISON OF THE COMFORT LEVEL OF THE

SINGLE LAYERED HOSPITAL TEXTILES DEVELOPED

Single layered hospital textiles were developed from

Lyocell and its blends with polyester

Micro lyocell and its blends with Micro polyester

Bamboo yarns with Cotton and lyocell

Bamboo charcoal yarn with lyocell

201

In all of the above mentioned fiber combinations, blended yarns

and fabrics were produced by varying the blend proportion and weave

structures. Among each set of fabrics, the fabrics having maximum comfort

properties are analyzed for their ability to fulfill the performance requirement

of hospital textiles. The following fabrics were found to have maximum

comfort properties and they are compared in terms of the essential properties

such as air permeability, thermal conductivity, water vapour permeability,

water absorption and water spreading ability.

Table 6.7 Comfort properties of selected single layered fabrics developed

Fabric

Lyocell

(100%)

Lyocell/

Polyester

(70:30)

Microlyocell/

Micro

polyester

(85:15)

Micro

lyocell

(100%)

Bamboo/

Lyocell

(25:75)

Bamboo

: Cotton

/Lyocell

(25:75)

Bamboo

Charcoal/

Lyocell

(50:50)

Air

permeability

cm3/cm

2/s

138.38 95.80 103 77.4 146.53 138.4 178.0

Thermal

conductivity,

w/m/k

0.022 0.011 0.034 0.043 0.038 0.097 0.0303

Water vapour

permeability

g/m2/day

6564.0 4435.1 4618.3 5133.2 2128.88 2993.73 2394.99

Water

absorption,

sec

7.00 6.00 0.03 0.02 0.01 0.03 8.00

Spreading

area, cm2

3.90 7.45 5.12 4.00 3.80 4.63 3.25

6.4.1 Analysis of the air permeability of hospital textiles developed

Figure 6.7 shows the air permeability of the few selected hospital

textiles developed. It is observed from the figure that the bamboo and bamboo

202

charcoal fiber based blended fabrics show higher air permeability than the

lyocell, micro lyocell blended fabrics. This trend may be attributed to the fine

micro pores present in the bamboo fiber. Blending of polyester with lyocell

reduces the air permeability. The air permeability value ranges from 77.4 to

178. Bamboo charcoal fabric has the maximum air permeability.

Figure 6.7 Air permeability characteristics of single layered bed linen

developed

6.4.2 Analysis of the Thermal conductivity of hospital textiles

developed

Figure 6.8 shows the thermal conductivity characteristics of the

selected single layered medical textile fabrics. Thermal conductivity is

maximum in the case of bamboo: cotton /lyocell, which may be due to the

best combination of the thermal conductive fabrics such as bamboo cotton

and lyocell.

203

Figure 6.8 Thermal conductivity characteristics of single layered bed

linen developed

Lyocell/polyester blended fabrics have the least thermal

conductivity due to the presence of polyester followed by micro lyocell and

micro polyester blended fabrics. Bamboo and bamboo charcoal blended

fabrics have higher thermal conductivity.

6.4.3 Analysis of the Water vapour permeability of hospital textiles

developed

Figure 6.9 shows the comparison of water vapour permeability of

the selected hospital textile fabrics. It shows an interesting trend of higher

water vapour permeability for the lyocell and micro lyocell blended fabrics

which may be attributed to the fine and smooth structure of lyocell fiber and

presence of polyester which reduces the formation of bonds between the

water molecules and hydrophilic fiber there by increasing water vapour

204

permeability. The bamboo fibers due to their higher attraction towards water

have lower water vapour permeability.

Figure 6.9 Water vapour permeability characteristics of single layered

bed linen developed

6.4.4 Analysis of the Water absorption of hospital textiles developed

Figure 6.10 Water absorption characteristics of single layered bed linen

developed

205

From the figure 6.10 it is observed that the lyocell, blends of

lyocell: polyester and bamboo charcoal fabrics have lower water absorbency.

The bamboo rich fabrics and the micro fiber fabrics have excellent water

management properties.

6.4.5 Analysis of the Water spreading area of hospital textiles

developed

From Figure 6.11, it is clear that water management ability of the

micro fibers and lyocell/polyester fabrics are better than other fibers.

Presence of polyester and polyester micro fibres influences the water

spreading ability of micro fiber and lyocell/polyester blended fabrics.

Figure 6.11 Water spreading characteristics of single layered bed linen

developed

Hence it can be concluded the hospital textile fabrics made of

lyocell/polyester and microlyocel/micro polyester blended fabrics have better

performance when compared to other fabrics.

206

6.5 COST ANALYSIS OF HOSPITAL TEXTILES

The cost of widely used hospital textiles made of cotton is given in

the Table 6.8. Depending on the count and fabric specification, the cost of

fabric per meter ranges from Rs.44 to Rs.72. The cost of hospital textiles

developed from the new generation fibres is given in the Table 6.9. The

Fabric cost /m2 ranges from Rs. 95 to Rs. 100 for single layered fabrics and

the single and multi layered fabrics made of Bamboo charcoal yarn costs

around Rs. 160 to Rs.450. Since the bamboo charcoal yarn is imported from

china and the yarn cost is high, compared to other fabrics, the bamboo

charcoal fabric cost is high. The multi layered fabric made of bamboo and

lyocell combination costs around Rs.110 to Rs. 155. The cost of newly

developed hospital textiles are 1.5 to 2 times costlier than the existing fabrics

made of cotton.

Table 6.8 Cost analysis of Existing bed linen

Cost of Existing Bed linen

S.No EPI x PPI Warp count x

Weft count

Size(cm) Cost per

piece(Rs.)

Cost/meter2

(Rs.)

1 26.7 x 26.7 30S x 30

S145 x 216 140 44.87

2 36 x 25 40S x 34

S102 x 216 100 45.87

3 42x 22 40S x 40

S160 x 216 190 55

4 22 x 16.5 2/40S

x 2/40S 145 x 216 225 72

5 17.3 x 14 10S x 10

S145 x 216 145 46.47

207

Table 6.9 Cost analysis of Hospital textiles developed

S.No Fibre type Yarn cost

(Rs)

GSM Grey

Fabric

Cost/ m

(Rs.)

Bleached

fabric

Cost/ m

(Rs.)

Dyed

fabric

Cost/ m

(Rs.)

1 Lyocell 360 150 71.5 77.5 90.3

2 Lyocell: Polyester 370 180 69 82.5 96.9

3 Bamboo 360 150 65.5 77.5 90.3

4 Bamboo:cotton/

Lyocell

340 150 70 76 89

5 Bamboo charcoal 3000 150 100%- 456

75:75 - 356

50:50 - 258

25:75 - 159

- -

6 Micro polyester:

Micro lyocell

500 150 75 84 90

7 Bamboo charcoal/

Lyocell Multi

layered Knitted

fabrics

BC-3000

MP- 500

L- 360

300 400 418 442

8 Bamboo/ Lyocell

Multi layered

Knitted fabric

B-340

L-360

MP-500

250 120 135 155

Bamboo charcoal/

Lyocell Multi

layered Woven

fabrics

BC-3000

MP- 500

L- 360

170 237 247 260

Bamboo/ Lyocell

Multi layered

Woven fabric

B-340

L-360

MP-500

170 86 96 110

Cost of mattress with Air circulation device

9 PU foam - 1000

Hollow fibre - 1000

Air circulation device - 2500

Total cost - 4500

Non woven and fabric cover - 1500

Mattress with air circulation device and air

permeable water impermeable cover: 6000

208

6.6 CONCLUSIONS

From the analysis of the comfort and moisture management

properties of existing hospital bed linen fabrics, it was found that fabrics

made of courser count yarn have higher air permeability when compared to

finer fabrics. The thermal conductivity is high for 16S count hospital bed linen

and least for 40S twill woven fabrics. All hospital bed linens exhibited

moderately good water absorbing property except the vat dyed blue fabric

made of 40s count fabric. The hospital bed linen fabrics made of 20

S, 30

S and

40S cotton fabrics showed maximum spreading area compared to other

fabrics. Coarser fabrics have high frictional coefficient and 40 S

count cotton

bed linen has less friction due to its finer yarn count and twill weave structure.

All the bed linens have equal water vapour permeability of around 1500 to

2000 g/m2/day.

From the analysis of the selected hospital textiles developed from

each category, it is observed that the bamboo and bamboo charcoal fibre

based blended fabrics have higher air permeability than the lyocell, micro

lyocell blended fabrics. Lyocell /polyester blended fabric have the least

thermal conductivity and bamboo, bamboo charcoal blended fabrics have

higher thermal conductivity. Higher water vapour permeability is noted for

lyocell and micro lyocell blended fabrics and the bamboo fibre fabrics have

lower water vapour permeability. The bamboo rich fabrics and the micro

fiber fabrics have excellent water management properties. Presence of

polyester and micro polyester influences the water spreading ability of micro

fibre and lyocell/polyester blended fibre fabrics.