DKS 2437:2013 
© KEBS 2013 – All rights reserved   1 KENYA STANDARD 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
STRETCH CLING FILM — SPECIFICATION  
 
 
 
 
 
 
          
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   
 
 
 
 
 
 
 
 
 
 
  
TECHNICAL COMMITTEE REPRESENTATION 
 
The following Organizations were represented on the  Technical Committee: 
 
University of Nairobi 
Government Chemist 
Kenyatta University 
Kenya Polytechnic 
MOR-Materials Dept. 
KIRDI 
CIN 
Unilever Kenya Ltd 
Kimfay E.A Ltd 
Ministry of Industrialization 
Kaluworks Ltd. 
Steel Wool EA Ltd 
Superbrite Ltd. 
3M Kenya Ltd 
Nakumatt Holdings Ltd 
Uchumi Supermarkets Ltd. 
Soilex Prosolve 
Statpack Industries Ltd 
 
 
 
 
 
 
 
REVISION OF KENYA STANDARDS 
 
In order to keep abreast of progress in industry, K enya Standards shall be regularly reviewed. 
Suggestions for improvements to published standards , addressed to the Managing Director, Kenya 
Bureau of Standards are welcome. 
 
 
 
 
© Kenya Bureau of Standards, 2013 
 
 
Copyright. Users are reminded that by virtue of Sec tion 25 of the Copyright Act, Cap. 12 of 2001  of t he Laws of Kenya, copyright 
subsists in all Kenya Standards and except as provi ded under Section 26 of this Act, no Kenya Standard  produced by Kenya 
Bureau of Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior 
permission in writing from the Managing Director. 
 DKS 2437:2013 
© KEBS 2013 – All rights reserved   3  
 
KENYA STANDARD 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 STRETCH CLING FILM—SPECIFICATION  
 
 
 
 
 
 
 
 
 
 
 
 
 
KENYA BUREAU OF STANDARDS (KEBS)  
 
Head Office:  P.O. Box 54974, Nairobi-00200, Tel.: (+254 020) 60 5490, 602350, Fax: (+254 020) 604031 
E-Mail: info@kebs.org , Web: http://www.kebs.org 
 
Cost Region  Lake Region  North Rift Region  
P.O. Box 99376, Mombasa-80100 P.O. Box 2949, Kisumu -40100 P.O. Box 2138, Nakuru-20100 
Tel.: (+254 041) 2229563, 2230939/40  Tel.: (+254 057) 23549, 22392  Tel.: (+254 051) 210553, 210555  
Fax: (+254 041) 229448 Fax: (+254 057) 21814 Fax: ( +254 051) 2210076 
E-Mail: kebs_msa@swiftmombasa.com E-mail: kebs_ksm@ swiftkisumu.com  
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
  
Foreword 
 
This first edition of this Kenya Standard was prepa red by the technical committee on Household Product s 
and endorsed by the Standards Projects Committee un der the authority of the National Standards 
Council. 
 
Cling film is used in sealing food items in contain ers to keep them fresh (for short time preservation ).The 
standard addresses quality, safety and clinging cap ability and environmental and plasticizer issues. T his 
standard has therefore covered the material require ments, clinging and stretching properties, 
environmental and safety concerns. The standard cov ers both perforated and non-perforated cling films.  
 
During the preparation of this standard, reference was made to the following: 
 
• IS 14995:2001 Stretch Cling Films – Specification 
• GB 10457:2008 Plastic Cling Wrap Film for keeping food fresh 
• ISO 2528:1995 Sheet materials - Determination of w ater vapour transmission rate - Gravimetric 
 (dish) method 
• ISO 15105-2:2003 Plastics — Film and sheeting —Det ermination of gas-transmission rate — 
 Part 2: Equal-pressure method 
• ASTM D882:2010 Standard Test Method for Tensile Properties of Thin  Plastic Sheeting1  
 
 
 
Acknowledgement is hereby made for the assistance d erived from these sources. 
 
 
 
 
 
 
 
 
 
 
 DKS 2437:2013 
© KEBS 2013 – All rights reserved   5  
 
 
 
 
KENYA STANDARD  
 
 Stretch Cling Film ——  SPECIFICATION 
 
1. Scope  
 
This Kenya Standard specifies requirements, methods  of sampling and test for stretch cling films. This  
standard covers stretch cling film for keeping food  fresh which is made of resin such as polyethylene,  
polyvinylchloride, polyvinyl dichloride, processed by the method of monolayer or multilayer extrusion.  It 
will cover perforated and non-perforated cling film s. 
 
2. Definitions 
 
2.1  Cling film- Plastic cling wrap with ability to adhe re to itself and made of resin to keep food fresh. 
2.2 Polyethylene cling film - A type of food-use cl ing film made of polyethylene. 
2.3 Polyvinyl chloride cling film - A type of food- use cling film made of PVC. 
2.4 Polyvinyl dichloride cling film- A type of food -use cling film made of PVDC. 
2.5  Multilayer extrusion cling film – A type of cl ing film processed by the method of multilayer 
extrusion. 
2.6 Self cling – The self cling property of the cli ng film itself; also called shear and peel strength . 
2.7 Open wrapping – the degree of difficulty of rem oving the film from the paper core during use. 
2.8 Anti-fogging- The property of preventing a clin g wrap film from forming any water drops or water 
 fogging on the film surface. 
 
3. Classification 
 Cling film shall be classified as follows: 
 a) On the basis of material where we have Polyethy lene, Polyvinylchloride and  Polyvinyl  
  dichloride 
 b) Perforations: Perforated and non-perforated. 
 
  
4. Requirements  
   
4.1 Materials 
4.1.1 Resin- The resin selected should be of food g rade material and shall comply where necessary 
 with KS 2322. 
4.1.2 Additives: The additives selected and their d osages should meet the requirements set out in KS 
2322   
4.2 Colour- Cling film shall be transparent, normal  natural colour 
4.3 Dimension: 
 Thickness for 
• non-perforated:  0.01mm0± 0.002 
• perforated:  
 
 
 
 
 
 
 
 
 
 
 Width = 200 to 1000mm 
4.4 Appearance: The material shall be uniform in co lour, texture and finish. The material shall be fre e 
from streaks and foreign particles. There shall be no other visible defects such as 
perforations/holes (for non-perforated), tears or b listers. The edges shall be free from nicks and 
cuts visible to unaided eye, free from wrinkles, fo ld-overcreases and gels. There shall be no 
splices or air bubbles.  
4.5 Odor, the film shall be free from any objection able odor. 
4.6 Tensile strength:  
 
 Table 1 Requirements  
 
  
Item Index 
PE PVC PVDC 
Tensile Strength 
(longitudinal, 
transverse) MPa >  10 >   15 >   60  
Nominal Tensile strain 
at break (longitudinal, 
transverse) % >  120  >  150  >  50  
Light Transmissivity, 
% >  90  >  92  >  90  
Haze ˂  3 ˂  2 ˂  3 
Deviation of gas 
transmission rate – 
Oxygen, % ± 20 
Deviation of gas 
transmission rate – 
Carbon dioxide, % ± 20 
Deviation of water 
vapour permeance, % ± 20 
Self Cling (shear and 
peel strength), N/cm 2 >  0.5 
Open wrapping The sample shall be completely peeled  off within 5 second 
Anti fogging Under test conditions, no water drops shall adhere to the film surface.  
 
 
 
5. Packaging 
 
The material shall be packaged to provide adequate protection during normal handling and transportatio n 
and each package shall contain only one size of mat erial The packaging shall be made of material free 
from contaminants, such as to maintain the integrit y of the cling film. Film bags or boxes shall be us ed as 
sealed packaging. 
 DKS 2437:2013 
© KEBS 2013 – All rights reserved   7 6. Marking  
 
Cling Film shall be marked legibly and indelibly wi th the following information: 
 
i) Product name  
ii) The name and/or registered trade mark of the ma nufacturer.  
iii) Address of manufacturer or importer. 
iv) “Made in Kenya” or country of origin where appl icable 
v) Recommended use 
vi) Instructions for disposal 
vii) Size in length by width  
viii) Standardization mark 
ix) Safety precautions e.g ‘microwave safe’ or ‘mic rowave unsafe’ 
 
 
Annex A 
Determination of Tensile Properties 
 
 
 
Apparatus 
A.1 Testing Machine —A testing machine of the constant rate-of-crosshea d-movement type and 
comprising essentially the following: 
A.1.1 Fixed Member —A fixed or essentially stationary member carrying one grip. 
A.1.2 Movable Member —A movable member carrying a second grip. 
A.1.3 Grips —A set of grips for holding the test specimen betwe en the fixed member and the movable 
member of the testing machine; grips can be either the fixed or self-aligning type. In either case, th e 
gripping system must minimize both slippage and une ven stress distribution. 
A.1.3.1 Fixed grips are rigidly attached to the fix ed and movable members of the testing machine. When  
this type of 
grip is used, care must be taken to ensure that the  test specimen is inserted and clamped so that the long 
axis of the test specimen coincides with the direct ion of pull through the center line of the grip ass embly. 
A.1.3.2 Self-aligning grips are attached to the fix ed and movable members of the testing machine in su ch 
a manner that they will move freely into alignment as soon as a load is applied so that the long axis of the 
test specimen will coincide with the direction of t he applied pull through the center line of the grip  
assembly. The specimens must be aligned as perfectl y as possible with the direction of pull so that no  
rotary motion will cause slippage to occur in the g rips; there is a limit to the amount of misalignmen t self-
aligning grips will accommodate. 
A.1.3.3 The test specimen shall be held in such a w ay that slippage relative to the grips is prevented  
insofar as possible. Grips lined with thin rubber, crocus-cloth, emery cloth, or pressure-sensitive ta pe as 
well as file-faced or serrated grips have been succ essfully used for many materials. The choice of gri p 
surface will depend on the material tested, thickne ss, etc. Line grips padded on the round face with 0 .75-
1.00 mm (0.030-0.040 in.) blotting paper or filter paper have been found superior. Air-actuated grips have 
been found advantageous, particularly in the case o f materials that tend to “neck” into the grips, sin ce 
pressure is maintained at all times (see Notes 1 -7). In cases where samples frequently fail at the ed ge of 
the grips, it could be advantageous to slightly inc rease the radius of 
curvature of the edges where the grips come in cont act with the test area of the specimen. 
NOTE 1—Caution needs to be taken when choosing the type of grips and the type of grip surfaces to use 
for testing specimens films composed of high streng th LLDPE and VLDPE resins. Test results tend to 
differ more when comparing these types of specimens  films tested with the grips lined with different 
materials. 
NOTE 2—The gage of pressure sensitive tape, thin ru bber, crocus-cloth, and emery cloth needs to be 
adequate enough to prevent slipping and premature f ailures of the test specimens (for example, pressur e  
 
 
 
 
 
 
 
 
 
 
 sensitive tape is used on the surface of the grips:  the test specimen can may begin to tear at the edg e of 
the grips during the test if the tape is too thin.) . 
NOTE 3—The grit size of crocus-cloth and emery clot h is suggested to be at least 800. The use of these  
materials helps to prevent test specimens from slip ping in the grips. One must be cautious when using 
these materials so that premature failures of the t est specimens do not occur. 
A.1.4 Drive Mechanism —A drive mechanism for imparting to the movable mem ber a uniform, controlled 
velocity with respect to the stationary member.  
A.1.5 Load Indicator —A suitable load-indicating mechanism capable of sh owing the total tensile load 
carried by the 
test specimen held by the grips. This mechanism sha ll be essentially free of inertial lag at the speci fied 
rate of testing (see Note 4). Unless a suitable extensometer is used , the mot ion of the weighing system 
shall not exceed 2 % of the 
specimen extension within the range being measured.  The load indicator shall determine the tensile loa d 
applied to the specimen with an accuracy of 61 % of  the indicated value, or better. The accuracy of th e 
testing machine shall be verified. 
A.1.6 Crosshead Extension Indicator —Asuitable extensionindicating mechanism capable of  showing the 
amount of 
change in the separation of the grips, that is, cro sshead movement. This mechanism shall be essentiall y 
free of inertial  lag at the specified rate of test ing (see Note 4) and shall indicate the crosshead movement 
with an accuracy of 61 % of the indicated value, or  better. 
A.2 Extensometer (Optional) —A suitable instrument used for determining the dis tance between two 
designated points on the test specimen as the speci men is stretched. The use of this type of instrumen t is 
optional and is not required in this test method. T his apparatus, if employed, shall be so designed as  to 
minimize stress on the specimen at the contact poin ts of the specimen and the instrument . It is desir able 
that this instrument automatically record the dista nce, or any change in it, as a function of the load  on the 
test specimen or of the elapsed time from the start  of the test, or both. If only the latter is obtain ed, load-
time data must also be taken. This instrument must be essentially free of inertial lag at the specifie d 
speed of testing ( see Note 4 ). 
A.2.1 Modulus of Elasticity and Low-Extension Measurement s —Extensometers used for modulus of 
elasticity 
and low-extension (less than 20 % elongation) measu rements shall, at a minimum, be accurate to 61 % 
and comply with the requirements set forth in Pract ice E83 for a Class C instrument. 
A.2.2 High-Extension Measurements —Instrumentation and measuring techniques used for high-
extension (20 % elongation or greater) measurements  shall be accurate to 610 % of the indicated value,  
or better. 
NOTE 4—A sufficiently high response speed in the in dicating and recording system for the load and 
extension data is essential. The response speed req uired of the system will depend in part on the 
material tested(high or low elongation) and the rat e of straining. 
A.3 Thickness Gauge —A dead-weight dial or digital micrometer appropria te for the material or specimen 
geometry being tested. 
A.4 Width-Measuring Devices —Suitable test scales or other width measuring devi ces capable of 
measuring 0.25 mm (0.010 in.) or less. 
A.5 Specimen Cutter  
A.5.1 Devices that use razor blades have proven esp ecially suitable for materials having an elongation -at-
fracture above 10 to 20 %. DKS 2437:2013 
© KEBS 2013 – All rights reserved   9 A.5.2 The use of a punch press or a striking die is  not recommended because of their tendency to 
produce poor and inconsistent specimen edges. 
A.5.3 The use of a cutting template and a single ra zor blade is not recommended as it will affect the 
parallelism of the test specimen. 
A.6 Test Specimens 
The test specimens shall consist of strips of unifo rm width and thickness at least 50 mm (2 in.) longe r 
than the grip separation used. The nominal width of  the specimens shall be not less than 5.0 mm (0.20 
in.) or greater than 25.4 mm (1.0 in.). A width-thi ckness ratio of at least eight shall be used. Narro w 
specimens magnify effects of edge strains or flaws,  or both. 6.4 The utmost care shall be exercised in  
cutting specimens to prevent nicks and tears that c ause premature failures ( seeNote 5).  The edges shall 
be parallel to within 5 % of the width over the len gth of the specimen between the grips.  
NOTE 5—Microscopical examination of specimens can b e used to detect flaws due to sample or 
specimen preparation. Test specimens shall be selec ted so that thickness is uniform to within 10 % of the 
thickness over the length of the specimen between t he grips in the case of specimens 0.25 mm (0.010 
in.) or less in thickness and to within 5 % in the case of specimens greater than 0.25 mm (0.010 in.) in 
thickness but less than 1.00 mm (0.040 in.) in thic kness. 
 
NOTE 6—In cases where thickness variations are in e xcess of those recommended above, results tend 
not to be characteristic of the material under test . 
 
If the material is suspected of being anisotropic, two sets of test specimens shall be prepared having  their 
long axes respectively parallel with and normal to the suspected direction of anisotropy. 
For tensile modulus of elasticity determinations, a  specimen gage length of 250 mm (10 in.) shall be 
considered as standard. This length is used in orde r to minimize the effects of grip slippage on test 
results. When this length is not feasible, test sec tions as short as 100 mm (4 in.) can be used if it has 
been shown that results are not appreciably affecte d. However, the 250-mm (10-in.) gage length shall b e 
used for reference purposes. The speed of testing o f shorter specimens must be adjusted in order for t he 
strain rate to be equivalent to that of 
the standard specimen. 
 
NOTE 7—Two round robin tests4 have shown that, for materials of less than 0.25-mm (0.010 in.) in 
thickness, line grips padded on the round side with  1.0-mm (0.040-in.) blotting paper give the same 
results with a 100-mm (4-in.) test section as a 250 -mm (10-in.) test section produces with flat-face g rips. 
 
NOTE 8—Excessive jaw slippage becomes increasingly difficult to overcome in cases where high 
modulus materials are tested in thicknesses greater  than 0.25 mm (0.010 in.). 
 
A.7. Conditioning 
A.7.1Conditioning —Condition the test specimens at 23 ± 2°C (73.4 ± 3 .6°F) and 50 6 10 % relative 
humidity for not less than 40 h prior to test. In c ases of disagreement, the tolerances shall be 61°C 
(61.8°F) and 65 % relative humidity. 
A.7.2 Test Conditions —Conduct the tests at 23 ± 2°C (73.4 ± 3.6°F) and 5 0 ± 10 % relative humidity 
unless otherwise specified by agreement or the rele vant ASTM material specification. In cases of 
disagreement, the tolerances shall be ±1°C (±1.8°F)  and ±5 % relative humidity. 
 
A.8. Number of Test Specimens 
A.8.1 In the case of isotropic materials, at least five specimens shall be tested from each sample.  
 
A.9. Procedure 
A.9..1 Select a load range such that specimen failu re occurs within its upper two thirds. A few trial runs 
could be necessary to select a proper combination o f load range and specimen width. 
A.9.2 Measure the cross-sectional area of the speci men at several points along its length. Measure the  
width to an accuracy of 0.25 mm (0.010 in.) or bett er. Measure the thickness to an accuracy of 0.0025 
mm (0.0001 in.) or better for specimens less than 0 .25 mm (0.010 in.) in thickness and to an accuracy of 
1 % or better for specimens greater than 0.25 mm (0 .010 in.) but less than 1.0 mm (0.040 in.) in 
thickness.  
 
 
 
 
 
 
 
 
 
 
 A.9.3 Set the rate of grip separation to give the d esired strain rate, based on the initial distance b etween 
the grips, Zero the calibrated load weighing system , extension indicator(s) and recording system. 
 
NOTE 9—Extensometers can be used for modulus of ela sticity determinations with the expectation of 
obtaining more accurate values than can be obtained  using grip separation as the effective gage length . 
Precautions must be taken to ensure that extensomet er slippage and undue stressing of the specimen do 
not occur.  
 
A.9.4 In cases where it is desired to measure a tes t section other than the total  length between the grips, 
mark the ends of the desired test section with a so ft, fine wax crayon or with ink. Do not scratch the se 
marks onto the surface since such scratches can act  as stress raisers and cause premature specimen 
failure. Extensometers can be used if available; in  this case, the test section will be defined by the  contact 
points of the extensometer.  
 
NOTE 10—Measurement of a specific test section is n ecessary with some materials having high 
elongation. As the specimen elongates, the accompan ying reduction in area results in a loosening of 
material at the inside edge of the grips. This redu ction and loosening moves back into the grips as fu rther 
elongation and reduction in area takes place. In ef fect, this causes problems similar to grip slippage , that 
is, exaggerates measured extension. 
 
A.9.5 Place the test specimen in the grips of the t esting machine, taking care to align the long axis of the 
specimen with an imaginary line joining the points of attachment of the grips to the machine. Tighten the 
grips evenly and firmly to the degree necessary to minimize slipping of the specimen during test. 
A.9.6 Start the machine and record load versus exte nsion.   When the total length between the grips is  
used as the test area, record load versus grip sepa ration.  When a specific test area has been marked on 
the specimen, follow the displacement of the edge b oundary lines with respect to each other with divid ers 
or some other suitable device. If a load-extension curve is desired, plot various extensions versus 
corresponding loads sustained, as measured by the l oad indicator. 
A.9.7 When an extensometer is used, record load ver sus extension of the test area measured by the 
extensometer. 
A.9.8 If modulus values are being determined, selec t a load range and chart rate to produce a load-
extension curve of between 30 and 60° to the X axis. For maximum accuracy, use the most sensitive load 
scale for which this condition can be met. The test  may be discontinued when the load-extension curve 
deviates from linearity. 
A.9.9 In the case of materials being evaluated for secant modulus, the test can be discontinued when t he 
specified extension is reached. 10.10 If tensile en ergy to break is being determined, some provision m ust 
be made for integration of the stress-strain curve.  This can be either an electronic integration durin g the 
test or a subsequent determination from the area of  the finished stress-strain curve  
A.10. Calculation 
A.10.1 Breaking Factor (nominal) shall be calculated by dividing the maxim um load by the original 
minimum width of the specimen. The result shall be expressed in force per unit of width, usually newto ns 
per metre (or pounds per inch) of width, and report ed to three significant figures. The thickness of t he film 
shall always be stated to the nearest 0.0025 mm (0. 0001 in.). 
 
Example— Breaking Factor = 1.75 kN/m (10.0 lbf/in.) of width  for 0.1300-mm (0.0051-in.) thickness. 
 DKS 2437:2013 
© KEBS 2013 – All rights reserved   11 NOTE 11—This method of reporting is useful for very  thin films (0.13 mm (0.005 in.) and less) for whic h 
breaking load is not proportional to cross-sectiona l area and whose thickness is difficult to determin e with 
precision. Furthermore, films which are in effect l aminar due to orientation, skin effects, nonuniform  
crystallinity, etc., have tensile properties dispro portionate to cross-sectional area.  
 
A.10.2 Tensile Strength (nominal) shall be calculated by dividing the maxim um load by the original 
minimum crosssectional area of the specimen. The re sult shall be expressed in force per unit area, 
usually megapascals (or pounds-force per square inc h). This value shall be reported to three significa nt 
figures. The maximum load can occur at the yield po int, the breaking point, or in the area between the  
yield point and the breaking point. 
 
NOTE 12—When tear failure occurs, so indicate and c alculate results based on load and elongation at 
which tear initiates, as reflected in the load-defo rmation curve. 
 
A.10.3 Tensile Strength at Break (nominal) shall be calculated in the same way as th e tensile strength 
except that the load at break shall be used in plac e of the maximum load (Note 12 and Note 13).  
NOTE 13—In many cases tensile strength and tensile strength at break are identical, but not always. 
A.10.4 Percent Elongation at Break shall be calculated by dividing the extension at th e moment of rupture 
of the specimen by the initial gage length of the s pecimen and multiplying by 100. When gage marks or 
extensometers are used to define a specific test se ction, only this length shall be used in the calcul ation; 
otherwise the distance between the grips shall be u sed. The result shall be expressed in percent and 
reported to two significant figures (see Note 12). 
A.10.5 Tensile Yield Strength , where applicable, shall be calculated by dividing  the load at the yield point 
by the original minimum cross-sectional area of the  specimen. The result shall be expressed in force p er 
unit area, usually megapascals (or pounds-force per  square inch). This value shall be reported to thre e 
significant figures. Alternatively, for materials t hat exhibit Hookean behavior in the initial part of  the curve, 
an offset yield strength shall be obtained. In this  case the value shall be given as “yield strength a t —% 
offset.” 
A.10.6 Percent Elongation at Yield , where applicable, shall be calculated by dividing  the extension at the 
yield point by the initial gage length of specimen and multiplying by 100. When gauge marks or 
extensometers are used to define a specific test se ction, only this length shall be used in the calcul ation. 
Before calculating, correct the extension for “toe compensation”. The results shall be expressed in 
percent and reported to two significant figures. Wh en offset yield strength is used, the elongation at  the 
offset yield strength shall be calculated. 
A.10.7 Elastic Modulus shall be calculated by drawing a tangent to the ini tial linear portion of the load-
extension curve, selecting any point on this tangen t, and dividing the tensile stress by the correspon ding 
strain. Before calculating, correct the extension f or “toe compensation” . For purposes of this 
determination, the tensile stress shall be calculat ed by dividing the load by the average original cro ss 
section of the test section. The result shall be ex pressed in force per unit area, usually megapascals  (or 
pounds-force per square inch), and reported to thre e significant figures. 
A.10.8 Secant Modulus , at a designated strain, shall be calculated by di viding the corresponding stress 
(nominal) by the designated strain. Elastic modulus  values are preferable and shall be calculated 
whenever possible. However, for materials where no proportionality is evident, the secant modulus valu es 
shall be calculated. The stress to be used in the c alculation is then determined by dividing the load at the 
designated strain on the load-extension curve by th e original average cross-sectional area of the 
specimen.  
 
 
Annex B 
Determination of Self Cling (Shear and Peel Strengt h) 
 
 
B.1 Sample preparation 
Cut 10 sheets of sample 50 mm long and 25 mm wide, with every two sheets forming a set. Place the 
adhesive sides of each set of samples face to face in a lap joint, the length of a lap joint being 15m m and  
 
 
 
 
 
 
 
 
 
 
 the width of the lap joint being 25mm. Lay the samp les on a smooth surface, use a rubber roller (diame ter 
of 40mm, length of 100mm, mass of 300g) and carry o ut reciprocation rolling and press on the lap joint  
three times, until there is no air left between the  lap jointed layers of cling wrap film. Leave the p repared 
samples in an environment under test conditions for  20 minutes and then conduct the test. 
 
B.2 Procedure 
Stretch out each set of the samples on a tension ma chine and determine the force needed to separate 
the two sheets of sample. The arithmetic mean value  of the five sets shall be regarded as the result. The 
stretching velocity, using an appropriate test inst rument, shall be 250± 50 mm/min. The self-cling (sh ear 
and peel strength) shall be determined by the formu la 
 
 /g1846 =/g3017
/g3028×/g3029 
 
Where 
T – The self cling (shear and peel strength), in Ne wton/centimetre 2 (N/cm 2) 
P - The force needed to separate the sample, in New tons N 
b -The width of the lap joint in cm 
a - The length of the lap joint in cm 
 
Annex C 
Determination of the open-wrapping 
 
C.1 Sample preparation 
 
Cut 6 sheets of sample 150mm long and 50mm wide, wi th every two sheets forming a set. Place  the 
adhesive sides of each set of samples face to face in a lap joint, the length of the lap joint being 1 00mm.  
 
C.2 Procedure 
 
Fix one end of the sample and at the other end of t he sample fix a 4g weight using the self-cling of t he 
cling wrap film or a piece of adhesive paper. Let t he weight down slowly and allow the sample to peel 
naturally. All three sample sets shall meet the pro perty requirements. 
 
Annex D 
Determination of the anti-fogging 
 
Add 200ml of water at a temperature of 23 oC ± 2 0C into each of three beakers with a volume of 1000m l. 
Use three equal sized pieces of cling wrap film, wi th the adhesive side facing down, to completely cov er 
each of the beaker mouths. Ensure the film surfaces  are flat, and put the three beakers into a low 
temperature tank at 3 oC to maintain a constant temperature. After 10 minu tes, check the adhesive state 
of the water drops on the surface of the cling wrap  film. All three samples shall meet the property 
requirements.  
 DKS 2437:2013 
© KEBS 2013 – All rights reserved   13 Annex E 
Determination of water vapour transmission rate – G ravimetric (dish) method 
 
Water Vapour Transmission Rate (WVTR) is the mass o f water vapour transmitted through a unit area in 
a unit time under specified conditions of temperatu re and humidity. It is expressed in grams per squar e 
metre per 24 h [g/(m 2 . d)]. 
 
NB; The WVTR depends upon the thickness, com position  and permeability of the constituent material or ma terials 
and upon the conditions of temperature and relative  humidity under which the test is carried out  
 
E.1 Principle 
Dishes containing a desiccant and closed by the ma terial to be tested are placed in a controlled 
atmosphere These dishes are weighed at suitable int ervals of time and the WTR is determined from the 
increase in mass when this increase has become prop ortional to the time interval. 
 
 
E.2 Apparatus and material 
Figure 1 shows examples of equipment which has prov ed satisfactory in use, but other equipment may 
be equally satisfactory. 
 
E.2.1 Test dishes , shallow, of glass, aluminium or stainless steel a nd of as large a diameter as can be 
accommodated on the balance to be used. The dishes should be light, but rigid and resistant to corrosi on 
under the test conditions. Dishes made from alumini um, grade Al 99,5 and protected by chemical or  
anodic oxidation have been found suitable. Each dis h has a groove around the rim for sealing the 
test piece with wax. This groove has a profile such  that the test piece can be sealed over the opening  of 
the dish and no water vapour can escape at or throu gh the edges of the test piece. The internal diamet er 
of the dish shall be equal to or very slightly larg er than the diameter of the waxing templates. The i nternal 
depth of the dish below the plane of the test piece  should be not less than 15 mm (deep dish) or 8 mm 
(shallow dish) and there shall be no obstruction wi thin the dish that might interfere with the flow of  water 
vapour between the test piece and the desiccant. Th e surface area of the bottom of the dish where it 
is filled with desiccant shall be similar to that o f the exposed surface of the test piece. Each dish shall be 
assigned a different number. 
 
E.2.2 Lids , each numbered to correspond with a dish and made from the same material as the dish, with 
an outer rim designed to fit neatly over the outsid e of the dish so that there is negligible loss of w ater 
vapour when the dishes are removed from the test at mosphere for weighing. 
 
E.2.3 Waxing templates , to place the wax easily and to a Ilow the test ar ea to be defined sealant 
exactly. Their diameter, D, should preferably be 79,8 mm + 0,4 mm (an area of -  50 cm*). If any other 
diameter of template is used, this fact shall be me ntioned in the test report. In no case shall the di ameter 
be less than 56,l mm, and shall be known to an accu racy better than 1 %. These templates may be either : 
a)  Cross-braced ring templates, which remain in place  during the test. Their diameter, D, is the internal 
diameter of the ring. As many ring templates as dis hes are required; 
or 
b) Cover templates, which must be taken off when th e applied wax has cooled, comprising a disc 
with a central handle, drilled with a small hole at  a suitable point (see figure I), and having the ed ge 
chamfered at an angle of approximately 45”. Their d iameter, D, is the diameter of this smaller circle. 
Small guides can be fixed to the template to centre  it automatically. A few templates are sufficient. 
 
E.2.4 Sealant , a wax mixture (see annex C) which adheres strongl y to both the dish and the test piece 
and is not brittle at ordinary temperature, not hyg roscopic and not susceptible to oxidation. A surfac e 
of 50 cm* of freshly melted wax when exposed for 24  h in condition B (see annex B) shall not change 
in mass by more than 1 mg. 
  
 
 
 
 
 
 
 
 
 
 
 E.2.5 Water bath , for melting the wax. 
 
E.2.6 Device for distributing the wax , of at least 25 ml capacity and a rapid rate of di scharge, such as 
a pipette with a discharge tube of about 3 mm i.d. or a metal pourer with an insulated handle. 
 
E.2.7 Cutting template  or test-piece cutter, of a size suitable for cutti ng circular test pieces of a diameter 
suitable for the dishes in use (see figure 1). This  diameter is slightly less than the inside diameter  of the 
top of the dish (see figure2).  
 
E.2.8 Desiccant , silica gel or anhydrous calcium chloride (CaCI,),  in the form of granules I,6 mm to 4 mm 
in size or alternatively in the form of a friable f laked product I,5 mm to 2,0 mm in size. 
 
NB:  The limiting saturation of 1 g of calcium chloride  is 0,l g of water. The limiting saturation of 1 g of s ilica gel 
is 0,04 g of water. 
 
E.2.9 Balance , for determining the mass of each dish, lid and co ntents to 0,l mg 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DKS 2437:2013 
© KEBS 2013 – All rights reserved   15  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  5.10 
E.2.10 Tongs , holders or other means of manipulating the dishes . 
 
E.2.11 Enclosure , in which the required controlled atmosphere can b e set (see annex B) and with air 
continuously circulated. The control shall be such that the specified conditions are re-established no t 
more than 15 min after the door of the enclosure ha s been closed.   
E.3 Preparation of test pieces 
Avoiding all damaged areas, cut from the sample, wi th the aid of the cutting template or test piece cu tter 
at least three circular test pieces of the appropri ate diameter, normally 90 mm (see figure I), for ea ch face 
to be tested. Mark the test pieces in some way so t hat the side to be exposed to the test atmosphere 
can be readily identified.  
 
E.4 Preparation of dishes 
The method of preparation of the dishes differs sli ghtly according to whether a cover or ring template  
is used. Always begin by carefully cleaning and dry ing the dishes and the templates. Introduce the 
desiccant into the dish then put the test piece (cl ause 8) on the dish with the required face upwards and 
then the waxing template, and make a vapour-tight w ax seal between the test piece and the dish. The 
work must be done rapidly in order to keep the abso rption of water vapour by the desiccant to a minimu m. 
WARNING - Care should be taken when handling hot wa x, as serious burns could occur if the wax is 
spilled or splashed. Suitable protective equipment such as glasses, gloves, etc. should be worn. 
 
DKS 2437:2013 
© KEBS 2013 – All rights reserved   17 E.4.1 Use of wax and a cover template 
 
Fill each dish with desiccant up to 3 mm to 4 mm be low the final position of the test piece and level by 
tapping. Melt the wax on the water bath  and fill t he dispensing device. Place the test piece centrall y in 
position, followed by the waxing template. Run the molten wax into the groove until it reaches the lev el of 
the upper surface of the waxing template and, after  cooling, complete the joint by removing air bubble s 
and hair cracks with a small gas flame. A warm spat ula may be run over the wax to assist in this proce ss, 
so that shrinkage cracks that may have developed du ring cooling will be closed. Remove the waxing 
template and examine the assembly to make sure that  the joint is satisfactory. To ensure that the waxi ng 
template comes away easily, it is advisable first t o smear a thin film of petroleum jelly around the e dge 
and to wipe away any excess which could contaminate  the test piece. 
Cover the assembly with a lid numbered to correspon d with the number of the dish. 
 
E.4.2 Use of wax and a ring template   
Fill each dish with desiccant up to a level of 3 mm  to 4 mm below the final position of the test piece  and 
level by tapping. Melt the wax on the water bath an d fill the dispensing device. Run the molten wax in to 
the circular groove round the dish until a slight m eniscus is produced above the inner edge of the gro ove. 
Place the test piece centrally in position on the d ish, followed by the ring template, and load it wit h a 1 kg 
weight. Run more wax into the annular space so form ed and, after cooling, complete the joint by emovin g 
any air bubbles and hair cracks with a small gas fl ame. A warm spatula may be run over the wax to assi st 
in this process, so that shrinkage cracks that may have developed during cooling will be closed. Remov e 
the weight and leave the ring in place. Cover th e assembly with a lid numbered to correspond with the   
number of the dish. 
 
E.5  Procedure 
 
E.5.1 General method 
Weigh all the prepared dishes, with their lids, on the balance  to the nearest 0,l mg. Place them upri ght in 
the enclosure controlled to the conditions of the t est after removing the lids. Carry out successive  
weighings of the dishes, with their lids, at suitab le intervals of time. The weighings shall be carrie d out as 
follows: 
Cover the dishes with their respective lids and rem ove them from the controlled enclosure using the 
tongs or holders and leave them for 15 min to reach  ambient temperature. Weigh the assemblies to 
the nearest 0,l mg, and return them to the enclosur e after again taking off the lids. Take care to wor k 
rapidly, taking the dishes in small groups always c ontaining the same number, so that the whole weighi ng 
operation always lasts about the same time (not exc eeding 30 min). It is also possible to work without  the 
lids, but in this case it is advisable to use blank  assemblies and transport and cooling of the dishes  must 
be done in a closed vessel with calcium chloride de siccant. 
The interval between weighings should preferably be  24 h, 48 h or 96 07, but shorter time intervals (f or 
example 3 h, 4 h or 8 h) may be necessary for mater ials with a high transmission rate. The choice 
depends on the transmission rate of the sheet being  tested; the gain in mass between two successive 
weighings should be at least 5 mg. The choice of ti me interval is to be made at the beginning of the t est. 
If the first weighing shows a gain in mass too larg e or too small, the subsequent time intervals for 
weighing may be modified. Continue the weighings un til the increase in mass of two successive 
weighings per unit time of exposure to the selected  atmosphere becomes constant to within 5 %. 
The test must be completed before the efficiency of  the desiccant is appreciably reduced. (In 
practice, the total increase in mass should not exc eed I,2 g for shallow dishes and 3,2 g for deep one s.) 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
 E.5.2  Use of blank assemblies 
If the sample is of low transmission rate and consi derable thickness, for example rubber, plastics or 
polyethylene-coated board, or is appreciably hygros copic, it is advisable to test two or more blank 
assemblies, prepared in the same manner but without  desiccant, in addition to the three normal test 
assemblies. All the measured masses are then correc ted at each time interval by subtracting the mean 
change in mass of the blank assemblies which underg o the same treatment. 
 
E.6 Expression of results 
 For each dish, represent the total increase in mas s graphically as a function of time of exposure, 
the test being completed when three or four points lie on a straight line showing a constant rate 
of passage of water vapour. Using this straight lin e, the WVTR for each test piece is then calculated,  in 
grams per square metre per 24 h, from the formula 
 
(i) 
 
where 
m1 is the rate of increase in mass, in milligrams per hour, determined from the 
graph; 
 
S is the area, known to within 1 %, in square There  is insufficient data available at this time to all ow 
centimetres (normally 50 cm’), of the tested surfac e of the test piece. 
 
If weighings are made at identical time intervals, it is possible to calculate the transmission rate 
for each test piece directly from the results, with out preparing a graph, by using the formula below 
 
(ii) 
 
/g2779/g2781/g2777 × /g1813/g2779 
/g1819 × /g1820 
 
where 
t is the total duration, in hours, of the last two exposure periods  
m2 is the increase in mass, in milligrams, of the ass embly during the time t. 
For several assemblies corresponding to a single sa mple of test material and to a single face, 
calculate the arithmetic mean of the results obtain ed in accordance with either formula (i)or (ii) abo ve in 
E.6.  
Report the mean WTR by rounding values over 100 g/( m 2.d): to the nearest 10 g/(m2.d); 
values from 10 g/(m 2.d) to 100 g/(m 2. d): to the nearest whole number; values less than 1 0 g/(m 2.d): to the 
first decimal place. 
 
 
 
DKS 2437:2013 
© KEBS 2013 – All rights reserved   19 Annex F 
Determination of gas-transmission rate — 
Equal-pressure method (Oxygen and carbon dioxide) 
 
F.1 Principle 
A test specimen is mounted in a gas-transmission ce ll (see Figures 3 and 4) so as to form a sealed 
barrier between two chambers. One chamber is slowly  swept with a carrier gas. The second chamber is 
fed with the test gas. The total pressure is identi cal (atmospheric) in each chamber but, since the pa rtial 
pressure of the test gas is higher in the second ch amber, the test gas permeates through the barrier i nto 
the carrier gas in the first chamber. 
 
The test gas which permeates through the specimen i s carried by the carrier gas to a sensor the nature  of 
which will depend on the material under test and th e test gas used. 
 
F.2 Test specimens 
Test specimens shall be representative of the mater ial under investigation, free from shrivelling, fol ds and 
pinholes, and of uniform thickness. They shall be l arger than the gas-transmission area of the 
measurement cell and be capable of being mounted ai rtight. Use three specimens unless otherwise 
specified or agreed upon among the interested parti es. Mark the side of the material facing the 
permeating gas. 
 
NOTE In principle, the test should replicate the ac tual conditions of use, with the permeating gas pas sing from the 
inside to the outside of e.g. packaging material, o r vice versa . 
 
Measure the thickness of each specimen in to the ne arest 1 µm, at at least 
five points distributed over the entire test area, and record the minimum, maximum and average values.  
 
F.3 Conditioning and test temperature 
F.3.1 Conditioning 
The specimens shall be  
either dried for not less than 48 h at the same tem perature as that at which the test is to be carried  
out, 
using calcium chloride or another suitable drying a gent in a desiccator; 
or conditioned at the temperature and humidity spec ified for the test for a length of time appropriate  
to the nature of the material under test. 
F.3.2 Test temperature 
Carry out the test in a room kept at 23 °C 2 °C, unless otherwise specified. 
 
F.4 Apparatus and materials 
F.4.1  General 
Figures 3 and 4 show examples of apparatus for dete rmining gas-transmission rate. The apparatus 
consists of a gas-transmission cell designed to all ow a test gas to permeate through a specimen, a 
sensor to measure the amount of test gas which has permeated through the specimen, and gas 
conditioning devices and flowmeters for the test ga s and carrier gas. 
 
F.4.2 Test gas 
The test gas may be either a single gas, or a mixtu re of gases. In the first case, the pressure of the  gas 
shall be equal to atmospheric pressure. 
In the second case, the pressure of the gas shall a lso be atmospheric and the partial pressure of each  
individual component will be determined by its conc entration in the mixture. 
 
F.4.3  Transmission cell 
The transmission cell is divided into two chambers by a test piece, cut from the sheet of material 
under test, to allow permeation of the test gas (se e 1 in Figures 3 and 4).  
 
 
 
 
 
 
 
 
 
 
 The test gas flows, under defined conditions, into chamber A and leaves this chamber through a 
suitably dimensioned outlet at ambient atmospheric pressure. 
A carrier gas flows through the other chamber (cham ber B) of the cell, under defined conditions, such 
that the pressure difference between the two chambe rs is as low as possible to prevent distortion of t he 
test piece. 
The shape of the cell shall be such that the test s pecimen is swept on both sides by laminar gas flows . 
In particular, the ratio of the effective permation  area to the volume of each chamber shall be such t hat 
the velocity of each gas is lower than a specified limit, depending on the shape of the cell. 
The effective permation area shall be adapted accor ding to the range of values to be determined. It is  
generally between 1 cm 2 and 150 cm 2. 
The effective permation area of the test specimen m ay be reduced by means of a mask placed between 
the two chambers. In this case, the mask shall be g lued on the test specimen and carefully checked for  
leaks, which would affect the measurements. 
When the cell is fitted with gaskets, the material used for the gaskets shall have a gas-transmission 
rate which is negligible compared to that expected for the material under test. 
 
F.5 Detection and measurement 
There are two methods for measuring amount of gas p ermeating through a specimen. 
 
 A: coulometric sensor (for oxygen-transmission rat e); 
 B: chromatographic sensor. 
NOTE The method used will depend on: 
•  the permeability of the material to the test gas; 
• the sensitivity required. 
 
F.6 Diffusion conditions 
Unless otherwise specified, the test gas and the ca rrier gas shall be conditioned under one of the set s of 
conditions of temperature and relative humidity giv en in Table 2. 
 
 
Table 2 — Conditions for diffusion 
 DKS 2437:2013 
© KEBS 2013 – All rights reserved   21  
 
 
 
F.7 Procedure 
Remove a test specimen from the conditioning atmosp here. Insert the specimen in the cell. 
Inspect the specimen for visual defects such as cre ases made during insertion. Connect the cell to the  
sensor. Using the two valves immediately upstream o f the cell, allow the carrier gas to flow through b oth 
chambers, A and B. The gas flow rate is generally s et at between 5 ml/min and 100 ml/min. Inspect the 
apparatus for leaks, then purge the apparatus compl etely, taking into account possible desorption from  
the specimen. Continue to purge the apparatus until  a constant signal is received from the sensor. 
Once a constant signal has been obtained, record th is value as the zero value. 
NOTE The time taken for the apparatus to stabilize may vary from less than one hour to several hours, depending on 
the material under test, its thickness and the test  conditions. 
Allow the test gas to flow into chamber A, under th e specified conditions of flow, temperature and 
humidity. The gas flow rate is generally set at bet ween 5 ml/min and 100 ml/min. Proceed until a const ant 
signal is obtained. Record this signal. Repeat with  the remaining specimens. 
 
F.8 Expression of results 
See Clause F.8. or F.10 depending on the method use d. 
 
F.9 Method for the determination of the oxygen-transmis sion rate using a 
coulometric sensor 
 
F.9.1 General 
This method is used to determine the amount of oxyg en permeating through the material, using a 
coulometric sensor which measures the amount of oxy gen which has permeated through the material and 
been carried out of the cell by the carrier gas. 
The sensor generates an electric current proportion al to the amount of oxygen flowing through the sens or 
per unit time. 
 
F.9.2 Apparatus 
Figure 3 shows a typical apparatus. 
 
 
 
 
 
 
 
 
 
 
 
 Valve 12 bypasses the sensor (9), thus avoiding the  cell (1) being swamped with air when the test 
specimen (2) is being placed in the cell. The valve s (7) immediately upstream of the transmission cell  
allow either carrier gas or test gas to be passed i nto chamber A of the cell. The catalyst bed (11) is  
intended to eliminate any traces of oxygen which mi ght be present in the carrier gas. 
 
NOTE Any other suitable means of removing oxygen fr om the carrier gas is acceptable. 
 
F.9.3 Carrier gas and test gas 
 The carrier gas shall be a mixture of dry nitrogen with 0,5 % to 3 % by volume of hydrogen. The  
volume fraction of oxygen in the carrier gas shall not exceed 100 µl/l. 
The test gas shall be dry oxygen containing at leas t 99,5 % by volume of O 2. 
 Gas-conditioning devices (see 4 in Figure 3) shall be placed upstream of the cell in order to achieve 
one of the sets of conditions given in Table 2. Dev ices for monitoring the humidity of the gases may b e 
fitted in the carrier and/or test gas circuits. 
 
 
 
 
 
 
 
 
 
 
 
DKS 2437:2013 
© KEBS 2013 – All rights reserved   23  
 
 
 
 
 
 
Figure 3 — Typical example of apparatus for determi nation of oxygen-transmission rate using a 
coulometric sensor  
 
 
 
 
 
 
 
 
F.9.4 Procedure 
Insert a test specimen, already conditioned, into t he transmission cell, and adjust the test condition s to 
the values applicable to the material and the speci fication. 
Purge both chambers (A and B), setting the carrier gas flow rate at the following value: 
5 ml/min to 25 ml/min for 30 min.For materials of v ery low permeability, increase the purge time, sett ing 
the carrier gas flow rate at the following values: 25 ml/min to 50 ml/min for the first 3 min to 4 min ; then 5 
ml/min to 25 ml/min for the next 30 min. Inspect th e apparatus for leaks. 
The electric current generated by the sensor is mea sured by passing it through a shunt fitted in 
parallel with a voltage-measuring device. Wait unti l the sensor signal stabilizes and record this valu e as 
the zero value. Reset the two valves (7) immediatel y upstream of the cell to allow oxygen to pass thro ugh 
chamber A and wait until a constant signal is obtai ned. Record the value of this signal. 
While some thin films with high transmission rates may reach equilibrium in 30 min to 60 min, thicker or 
more complex materials may require several hours to  reach a steady state of oxygen transmission.  
Record the time required in the test report. Repeat  the procedure with the remaining specimens. 
 
F.9.5 Expression of results 
Oxygen-transmission rate 
The oxygen-transmission rate is calculated using th e following  equation: 
where 
O2GTR is the oxygen-transmission rate, expressed in m oles per square metre second pascal 
[mol/(m 2.s.Pa)]; 
 
U is the voltage for the specimen, expressed in volts ; 
U0 is the zero-value voltage, expressed in volts; 
k is the calibration constant for the apparatus; 
 
 
 
 
 
 
 
 
 
 
 
 pa is the ambient atmospheric pressure, expressed in  pascals; 
pO is the partial pressure of oxygen in the test gas , expressed in pascals; 
A is the effective permeation area, expressed in squa re metres. 
 
NOTE In practice, the voltages U and U0 include the calibration constant for the apparatu s. 
 
Oxygen permeability, or coefficient of oxygen perme ability 
The gas permeability, or coefficient of permeabilit y, P is a physical characteristic of a polymer material,  
only depending on the test gas and the test conditi ons.  
 
The theoretical value of P is given by the equation: 
 
 
Where 
 
P is the oxygen permeability, or the coefficient of o xygen permeability, expressed in mole metres 
per square metre second pascal [(mol.m)/(m 2.s.Pa)]; 
O2GTR is the oxygen-transmission rate, expressed in m oles per square metre second pascal 
[mol/(m 2.s.Pa)]; 
 
d is the thickness of the specimen, expressed in metr es. 
O2GTR is generally expressed in cubic centimetres per  square metre 24 h [cm 3/(m 2.24 h)], the volume of 
the gas being converted to standard conditions. 
 
P is often expressed in cubic centimetre millimetres per square metre 24 h atmosphere [(cm 3.mm)/(m 2.24 
h.atm)] 
d used to be expressed in millimetres. 
 
 
 
F.10 Detection by gas chromatography 
F.10.1 General 
This method is used for the determination of the ga s-transmission rate of various gases or mixtures of  
gases using a gas chromatograph with columns suited  to the nature of the gas or gases concerned. 
 
F.10.2 Principle 
Gas molecules which permeate through the test speci men in the transmission cell are carried by the 
carrier gas to a sampling loop which allows the tot al contents of the sampling loop to be injected 
repeatedly into a gas chromatograph. The peaks in t he chromatogram obtained are compared with a 
calibration graph prepared from chromatograms produ ced using calibration standards. 
 
NB  Automatic injection valves may induce a pressur e back-up and hence an overpressure in the transmis sion cell. 
In such cases, it is necessary to compensate for th is overpressure to avoid the test specimen being di storted. 
DKS 2437:2013 
© KEBS 2013 – All rights reserved   25 Figure 4 shows a typical apparatus. 
 
F.10.3 Chromatograph 
F.10.4  General 
Various gas-chromatographic columns and detectors a re suitable, depending on the test gas involved. 
Some are described here. Other columns and detector s may be used for specific test gases or to ensure 
the required sensitivity. 
F.10.5 Packed column used with thermal-conductivity  detector (TCD) 
This equipment is applicable to:  O2, CO 2 and/or N 2; mixtures of these gases or other gases. 
NB Gas conditioning (see Table 2) may be carried ou t upstream of the transmission cell, but it is not advisable to 
condition the carrier gas when using a TCD sensor. 
 
F.10.6  Packed column used with flame-ionization de tector (FID) 
This equipment is applicable to:  CO 2 where high sensitivity is required, the chromatogra ph being fitted 
with an upstream methanization oven;  various organic gases. 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
Figure 4 —Typical example of apparatus for determin ation of gas-transmission rate using 
DKS 2437:2013 
© KEBS 2013 – All rights reserved   27 gas-chromatographic detection 
 
F.10.7 Capillary column used with ionization detect or (FID) 
This equipment is applicable to high-molecular-mass  organic vapours, such as odours or aromas. 
In such cases, care shall be taken to avoid condens ation of the vapour as it passes through the 
transmission 
cell and the chromatographic column and detector. 
 
 
 
F.10.8 Carrier gas and test gas 
The carrier gas shall be compatible with the detect ion equipment. The concentration of each gas in a 
mixture of test gases and the purity of the test ga s shall be known to within ± 1 %. 
Gases shall not contain impurities which may affect  the measurements. 
 
F.10.9 Calibration graph 
F.10.9.1 General 
A calibration graph may be obtained for the chromat ographic column.  
Order, from specialized suppliers, gas cylinders co ntaining gas mixtures with known concentrations of the 
gas of interest and covering a concentration range straddling the expected values of the future 
measurements. 
Connect each gas cylinder in turn upstream of the s ampling loop, and record the chromatogram 
for each under the same conditions. 
 
F.10.9.2  Preparation of calibration graph 
For either method, the chromatograms recorded can b e used to produce a graph relating the detector 
signal to the concentration of the gas of interest in the carrier gas. 
F.10.9.3 Procedure 
Feed the gas which permeates through the test speci men to the sampling loop and injecting samples 
onto the column in accordance with the chromatograp h manufacturer’s instructions. Monitor the detector  
response for the gas of interest, continuing until the detector signal has reached a steady value. Rec ord 
the time required in the test report. Using the int egrator of the chromatograph, determine the area of  the 
peak in the chromatogram corresponding to the gas o f interest. 
Determine, from the calibration graph the concentra tion of the gas of interest in the carrier gas. 
In parallel, using a calibrated flowmeter (e.g. a s oap-bubble flowmeter) determine the flow rate of th e 
carrier gas through the column. This measurement ma y be performed at the carrier gas outlet (9) after 
diverting the gas from the column by closing off th e sampling loop (10) (see Figure 4). 
 
F.10.9.4 Expression of results 
 
F.10.9.4.1 Gas-transmission rate 
The gas-transmission rate is calculated using the f ollowing equation: 
 
where 
GTR is the gas-transmission rate of the gas of inte rest, expressed in moles per square metre second 
pascal [mol/(m 2.s.Pa)]; 
D is the carrier gas flow rate, expressed in cubic ce ntimetres per minute; 
C is the concentration, by volume, of the gas of inte rest in the carrier gas, as measured from the 
chromatogram; 
 
 
 
 
 
 
 
 
 
 
 
 A is the effective permeation area of the test specim en, expressed in square metres; 
pa is the ambient atmospheric pressure, expressed in  pascals; 
p0 is the partial pressure of the gas of interest in  the test gas, expressed in pascals. 
 
F.10.9.4.2 Gas permeability, or coefficient of gas permeability 
The gas permeability, or coefficient of permeabilit y, P is calculated using the following equation: 
 
P=GTR × d 
 
where 
 
P is the gas permeability, or coefficient of gas perm eability, expressed in mole metres per square 
metre second pascal [(mol.m)/(m 2.s.Pa)]; 
 
GTR is the gas-transmission rate, expressed in mole s per square metre second pascal [mol/(m 2.s.Pa)]; 
 
d is the average specimen thickness, expressed in met res. 
 
NB: GTR is generally expressed in cubic centimetres  per square metre 24 h [cm 3/(m 2.24 h)], the volume 
of the gas 
being converted to standard conditions under a pres sure of one atmosphere. 
P is often expressed in cubic centimetre millimetres per square metre 24 h atmosphere 
[(cm 3.mm)/(m 2.24 h.atm)] and d used to be expressed in millimetres. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DKS 2437:2013 
© KEBS 2013 – All rights reserved   29