a presentation on how to use air permeabilty tester tall presentation given by zeeshan rajput at muet jamshoroo

3. ContentsContents
1)1) IntroductionIntroduction
2)2) Importance of testImportance of test
3)3) ObjectiveObjective
4)4) Construction of machine & working PrincipleConstruction of machine & working Principle
Machine modelMachine model
5.5. InstructionsInstructions
1.Standards1.Standards
2.Prepration of sample2.Prepration of sample
3.Operation3.Operation
4.Calculation4.Calculation
6.6. Factors affects on permeabilityFactors affects on permeability
7.7. ReferencesReferences

5. IntroductionIntroduction
Air permeability of a fabricAir permeability of a fabric
is a measure of how well itis a measure of how well it
allows the passage of airallows the passage of air
through it.through it.
OROR
The volume of air in mmThe volume of air in mm
which is passed in onewhich is passed in one
second through 100mm^2second through 100mm^2
of the fabric at a pressureof the fabric at a pressure
difference of 10 mm headdifference of 10 mm head
of water .of water .

6. Permeability is a measure of the ability of a porous material to transmit fluids.
It is an important property of technical textiles particularly in protective applications,
such as auto and wearable airbags where even the low permeability of the fabric can
extend the interactive time in impact. Limited permeability of parachute fabric can
stabilise its descent.
Fabric permeability relates to its geometric structure strongly as well as to the path of
streamlines for flow through the structure. Therefore, development of an analytical fabric
permeability model requires a background of fluid mechanics and knowledge of
mechanics of textile fabrics.
Permeability is dependent upon the porosity of the fabric. The porosity is largely
determined by the tightness of the fabric weave. Therefore any fabric that has
reasonably tight weave is suitable for this perspective

8. Importance of testImportance of test
Wear comfortWear comfort
Maintenance of wear comfort is directly relate to air permeability as,Maintenance of wear comfort is directly relate to air permeability as,
PerspirationPerspiration : perspiration helps to lose heat through the body when: perspiration helps to lose heat through the body when
its enrapture rise heat is taken from the body byits enrapture rise heat is taken from the body by
waterwater
vapours in order to supply the heat needed tovapours in order to supply the heat needed to
evaporat the moisture from the skin .evaporat the moisture from the skin .
HypothermiaHypothermia : In cold weather high loss of heat as during working can: In cold weather high loss of heat as during working can
cause frostbite or hypothermia which can causecause frostbite or hypothermia which can cause
irreparable body damage or even death.irreparable body damage or even death.
DehydrationDehydration : in hot weather perspiration is the only problem and: in hot weather perspiration is the only problem and
the sensation of wetness, it can cause dehydrationthe sensation of wetness, it can cause dehydration
oror
heat stroke by large heat lose.heat stroke by large heat lose.

10. ObjectiveObjective
Finding different values of air flow from fabricFinding different values of air flow from fabric
samples at different pressures , for testingsamples at different pressures , for testing
required quality of fabric for require use .required quality of fabric for require use .

11. Air permeability of fabrics with various densities

13. Machine model : MO21SMachine model : MO21S
Machine measure permeability byMachine measure permeability by
drawing air through the specimen with adrawing air through the specimen with a
vacuum pump.vacuum pump.
air flow measured by a selected flow meter .air flow measured by a selected flow meter .
instrument has 4 flow meter.instrument has 4 flow meter.
ranges of air flow 0.05 ml/sec to 416 ml/secranges of air flow 0.05 ml/sec to 416 ml/sec..

14. This is the schematic diagram or internal structure of machine you can get a clear
idea that how
internal parts are connected or assembled with each other.
Schematic Diagram
Air pump
Flow meter tubes
Manometer
Clamping device
Pressure valve
Pressure valve

15. Construction of machineConstruction of machine
• clamping device for securing the testclamping device for securing the test
specimen in a flat tensionless state.specimen in a flat tensionless state.
• device to prevent air leaking from thedevice to prevent air leaking from the
edges called guard ringedges called guard ring
• a pressure gauge or manometer toa pressure gauge or manometer to
measure the pressure drop from sidemeasure the pressure drop from side
of the specimen to the other.of the specimen to the other.
• an air pump to draw a steady flow ofan air pump to draw a steady flow of
air through the clamped specimenair through the clamped specimen
• a means of adjusting the airflow rate toa means of adjusting the airflow rate to
achieve specific pressure drop fromachieve specific pressure drop from
one side of the specimen to the other.one side of the specimen to the other.
• a flow meter to measure the actuala flow meter to measure the actual
rate of air flow through the specimenrate of air flow through the specimen

17. InstructionsInstructions
• StandardsStandards
• Preparation of samplePreparation of sample
• OperationOperation
• calculationcalculation
For testing sample and operating machine we need to know following in formations

18. standardsstandards

19. Air flow range = 0.05 to 416.0 ml/secAir flow range = 0.05 to 416.0 ml/sec
4 * flow meters = flow meter no.1 = 0.1 to 1.0 ml/sec4 * flow meters = flow meter no.1 = 0.1 to 1.0 ml/sec
flow meter no.2 = 0.4 to 5.8 ml/secflow meter no.2 = 0.4 to 5.8 ml/sec
flow meter no.3 = 4 to 40 ml/secflow meter no.3 = 4 to 40 ml/sec
flow meter no.4 = 4 to 400 ml/secflow meter no.4 = 4 to 400 ml/sec
0402 0301

20. Standard Measuring Chamber = BS5636:1990Standard Measuring Chamber = BS5636:1990
Test Area = 508 mm^2+- 1mm^2Test Area = 508 mm^2+- 1mm^2
Orifice diameter= 25.432 mm +-0.25mmOrifice diameter= 25.432 mm +-0.25mm
Test specimen = subject to sample sizeTest specimen = subject to sample size
Recommended Measuring Chamber =Recommended Measuring Chamber =
ENIso9237:1995ENIso9237:1995
Test area = 20 cm^2 +- 0.5 %Test area = 20 cm^2 +- 0.5 %
Orifice Dia = 50.46mmOrifice Dia = 50.46mm
Test specimen = subject to sample sizeTest specimen = subject to sample size

21. Pressure measurementPressure measurement
Direct reading = Maximum range 2kPa (204 mm water )Direct reading = Maximum range 2kPa (204 mm water )
Manometer = NB (1Pa = 0.102 mm water)Manometer = NB (1Pa = 0.102 mm water)

22. Instrument weight and DimensionsInstrument weight and Dimensions
weight of instrument =15kgsweight of instrument =15kgs
weight of pump unit = 11 kgsweight of pump unit = 11 kgs
overall size of instrument = 370D * 660W *600ltoverall size of instrument = 370D * 660W *600lt
overall size of pump unit = 200 * 270 * 350overall size of pump unit = 200 * 270 * 350

23. Preparation of samplePreparation of sample

24. Preparation of samplePreparation of sample
Condition the fabric to be tested for 24 hour by the standard B51051 :Condition the fabric to be tested for 24 hour by the standard B51051 :
relative humidity 65+_ 5 rh temperature 20+_2 c .relative humidity 65+_ 5 rh temperature 20+_2 c .
Conditioning room with above mentioned conditions
Analysis of sample for selecting flow
meter tube, e.g porous or what ……

25. The preparation of stack sample (a shipment or a party taken from the track number)
To prepare mass sample, random samples are taken at least as much as the number
shown in Schedule from a party. In mass sample, there should not be the moisture
exposed or damaged, the follow-up gives the pieces during transportation.
The Number of parts in a partyThe Number of parts in a party Minimum number of parts in StackMinimum number of parts in Stack
SamplesSamples
≤≤33
4-104-10
11-3011-30
31-7531-75
≥≥7676
11
22
33
44
55
Schedule - Mass Sample

26. Mass, from each piece that makes up the sample, a laboratory sample, the single most
and at least 1m in length is cut ( It should be provided randomly from one place from
the most recent tip of the part at least 3 m distance). It is necessary to ensure that there
are no wrinkle regions and a visible mistake in a laboratory sample. Before the experi-
ment,the samples should be conditioned and the experiment should be done in standard
atmospheric conditions
The suggested conditions for the experiment:
Experimental surface area = 20 cm2
Pressure drop = 100 Pa for clothing fabrics
Pressure drop = 200 Pa for industrial fabrics

27. Operation of machine contains following 14 steps follow
these steps and operate the machine easily.

28. Precautions
Close all valve of machine carefully before operating the machine operate machine
if you know the method look any damaged part if any like open wire etc.

29. Insert the plug and On the main electric switch
Step 1

30. slide fabric between the measuring chamber and the top clamp and firmly screen downslide fabric between the measuring chamber and the top clamp and firmly screen down
the knurled cap avoiding air leakage at the edges of the fabricthe knurled cap avoiding air leakage at the edges of the fabric
Step 2

31. set manometer to zero (0) adjust by using black knob if require.set manometer to zero (0) adjust by using black knob if require.
Step 3

32. Completely close control valve A and C valve B should never be fullyCompletely close control valve A and C valve B should never be fully
closed because it is for fine adjustments .closed because it is for fine adjustments .
Step 4
Valve “A”
Valve “C”Valve “B”

33. select flow meter by switches on the front of machineselect flow meter by switches on the front of machine
Step 5
Flow meter
Is selected
On the basis
Of fabric e.g if
Fabric is looking
Porous so for this
We should on
Tube 3 or 4
Because these
Tubes measure
Pressure
From 4 to 40 & 400 ml
And we know porous
fabric can pass flow in
b/w These range.

34. select flow tube no4 using flow tube select tube according to fabricselect flow tube no4 using flow tube select tube according to fabric
Step 6

35. Turn on vacuum pump using foot switch for passing air through specimenTurn on vacuum pump using foot switch for passing air through specimen
Step 7

36. Regulate flow of air through specimen by the help of valves and the selectedRegulate flow of air through specimen by the help of valves and the selected
flow meter.flow meter.
For information

37. Gradually open valve “C” until the required pressure is shown on the manometer tubeGradually open valve “C” until the required pressure is shown on the manometer tube
Standard is 100Pascal.Standard is 100Pascal.
Step 8

38. Note reading when manometer indicate selected pressureNote reading when manometer indicate selected pressure
Step 9
A particular pressure will be selected
on manometer by regulating valve “c”
Note reading at flow tube after selecting pressure at manometer

39. If the flow tube float has not moved close valve cIf the flow tube float has not moved close valve c
Step 10

40. select flow tube no3 and repeat above again no valve movement close valve cselect flow tube no3 and repeat above again no valve movement close valve c
Step 11
3

41. If again no movement of float select flow tube no2If again no movement of float select flow tube no2
Step 12
2

42. Gradually open " valve A " until required pressure drop is shown on the manometerGradually open " valve A " until required pressure drop is shown on the manometer
Valve “A” is used for Flowing tube 1 and 2
Step 13

43. if float tube does not rise as in case of flow tube no3 and above closeif float tube does not rise as in case of flow tube no3 and above close
valve “A” switch to flow tube 1 and gradually open " valve A " until requiredvalve “A” switch to flow tube 1 and gradually open " valve A " until required
pressure drop is shown on the manometer.pressure drop is shown on the manometer.
Step 14
01

44. Record reading across the top of the float if it rise upRecord reading across the top of the float if it rise up
Step 14

45. 1.Preparing appropriate samples in accordance with standard for
the air permeability
2.Conditioning the samples
3.Setting the pressure and time of the air permeability test device
in accordance with the sample.
4.Placing the sample to the device
5.Running the device
6.Reading the value of air permeability of the sample from the
indicator of the device at the end of the test.
7.After taking the arithmetic mean of the test results, to calculate
the value of air permeability.
8.Repeating the test for the appropriate number of samples in
accordance with standard.
Conclusion

46. calculationcalculation

47. Air permeability (R) is calculated as mm / s by using the following equation .

48. The pressure drop caused by the resistance of theThe pressure drop caused by the resistance of the
specimen is measured by a different pressure gaugespecimen is measured by a different pressure gauge
the out put is the air resistance R measured inthe out put is the air resistance R measured in
kilopascals time’s seconds/meter (k Pa.s/m ) foundkilopascals time’s seconds/meter (k Pa.s/m ) found
from this equation :R=P1-P2/v=^p/v where P1 isfrom this equation :R=P1-P2/v=^p/v where P1 is
pressure 1 and P2 is pressure after passing frompressure 1 and P2 is pressure after passing from
volume vvolume v
Follow below stepsFollow below steps
volume flow of air per unit water pressure per unit areavolume flow of air per unit water pressure per unit area
of fabric . calculate the mean air flow from the 5 or 10of fabric . calculate the mean air flow from the 5 or 10
flow meter reading in litres/minutes orflow meter reading in litres/minutes or
millimeters/minute (depended upon flow meter read)millimeters/minute (depended upon flow meter read)
then convert to ml/second.then convert to ml/second.
Solution Method

49. this is then divided by the test area of thethis is then divided by the test area of the
specimen (508^2) / 100 .specimen (508^2) / 100 .
record the result to an accuracy of 5 % i.e 2 or 3record the result to an accuracy of 5 % i.e 2 or 3
significant figures quoting the air permeability insignificant figures quoting the air permeability in
ml/(cm^2/s) quoting the air permeability inml/(cm^2/s) quoting the air permeability in
ml/cm^2/s at 100 Pa or whatever pressure toml/cm^2/s at 100 Pa or whatever pressure to
meat other specifications.meat other specifications.
e.g mean flow meter readied = 0.5e.g mean flow meter readied = 0.5 liters/minuteliters/minute
=0.01=0.01 liters/secondliters/second
=10=10 ml /secondml /second
therefore 10*100 = air permeability 2.0 ml cm^2/s attherefore 10*100 = air permeability 2.0 ml cm^2/s at
(100 Pa ).(100 Pa ).

50. Figures 4 and 5 show a p vs. t graph as obtained and the air permeability calculated
as volume of free air (i.e. reduced to 100 kPa).
It can be shown that:
Air permeability of the fabric = (V. dp/dt) / (Patm .A ) in appropriate units,
Where,
V = effective tank volume
dp/dt = rate of pressure decay
A = test area
Patm = atmospheric pressure= 0.987 bar
Figure 4: Pressure vs. time graph
for a nylon 66 fabric
Figure 5: Calculated fabric
air permeability vs. pressure

52. 1.Type of material
2.Linear density of yarns "warp-weft"
3.Warp and weft density per cm
5.Twist factors
5.Type of spinning
6.Difference of denting system
7.Type of stitches
8.Form and relative porosity
9.Type of woven construction
10.Thickness & weight
Factors AffectingFactors Affecting

53. • Construction factor and finishing techniques can have anConstruction factor and finishing techniques can have an
appreciable effect upon air permeabilityappreciable effect upon air permeability
• By causing a change in the length of airflow pathsBy causing a change in the length of airflow paths
through a fabric .hot calendaring thus can be used tothrough a fabric .hot calendaring thus can be used to
flatten fabric componentsflatten fabric components
• Fabrics with different surface textures on either side canFabrics with different surface textures on either side can
have a different air permeability depending upon thehave a different air permeability depending upon the
direction of air flow (ASTM-D737-04)direction of air flow (ASTM-D737-04)

54. • For woven fabrics yarn twist is also important asFor woven fabrics yarn twist is also important as
twist increases the circularity and density of the yarntwist increases the circularity and density of the yarn
increase thus reducing the yarn diameter and coverincrease thus reducing the yarn diameter and cover
factor and increasing the air permeabilityfactor and increasing the air permeability
• Yarn crimp and weave influence the shape andYarn crimp and weave influence the shape and
area of the interstices between yarn and may permitarea of the interstices between yarn and may permit
yarns to extend easily such yarn extension wouldyarns to extend easily such yarn extension would
open up the fabric ,increase the air permeabilityopen up the fabric ,increase the air permeability
(ASTM-D737-04)(ASTM-D737-04)

56. Manual of machine
Fabric Testing book
Textile Testing
Physical Testing of
Textiles
Textile learner
Teachers help
Source How to reach to source
Go to TTQC lab Textile MUET or contact company
Central library MUET reference hall, textile books section
Central Library MUET reference hall, textile books section
Textile Department MUET department library
www.textilelearner.blogspot.com
Madam Sidhra