DRAFT UGANDA STANDARD  
  DUS 202-4 
First Edition  
2015-mm-dd 
 
 
 Reference numbe r 
DUS 202-4: 2015 
© UNBS 2015  
  
Flexible polyurethane foams  — Part 4: Polyester type — 
Specification  
 DUS 202-4: 2015 
ii © UNBS 2014  – All rights reserved  
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are  
responsible for its correct application  
© UNBS 200 7  
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Uganda  
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E-mail: unbs@infocom.co.ug  
Web: www.unbs.go.ug  
 DUS 202-4:2015 
© UNBS 2015 – All rights reserved  iii 
 Foreword  
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Tourism, Trade and 
Industry established under Cap 327 , of the Laws of Uganda.  UNBS i s mandated to co -ordinate the 
elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT/SPS  Agreements of the World Trade Organisation (WTO).  
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and consists of representatives of 
consumers, traders, academicians, manufacturers, government and other stakeholders.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments b efore recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council.  
Committee membership  
 
 DRAFT UGANDA STANDARD  DUS 202-4: 2015 
 
© UNBS 2015– All rights reserved  1 
 Flexible Polyurethane foams  — Part 4: Polyester type — 
Specification  
1  Scope  
This draft Uganda standard spec ifies requirements  and methods of sampling and test  for five classes (based 
on density) of flexible polyurethane foams of the polyester type, in the form of blocks, slabs, sheets, or other  
shapes cut from these. Each class is subdivided, according to the h ardness of the foam, into two grades.  
2 Normative references  
The following referenced documents are indispensable for the application of this document. For dated 
references, only the edition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies.  
ISO 1798, Flexible cellular polymeric materials — Determination of tensile strength and elongation at break  
 ISO 1856, Flexible cellular polymeric materials — Determination of compression set  
 ISO 192 3, Cellular plastics and rubbers — Determination of linear dimensions  
ISO 23529, Rubber – General procedures for preparing and conditioning test pieces for physical test methods.  
 ISO 2439:2008, Flexible cellular polymeric materials — Determination of hard ness (indentation technique)  
 ISO 2440, Flexible and rigid cellular polymeric materials — accelerated ageing tests  
 ISO 3385, Flexible cellular polymeric materials — Determination of fatigue by constant -load pounding  
ISO 8067:2008 F lexible cellular polymer ic materials -- Determination of tear strength  
 ISO 8307, Flexible cellular polymeric materials — Determination of resilience by ball rebound  
US ISO 845, Cellular plastics and rubbers — Determination of apparent density  
3  Definitions  
For the purposes of t his specification the definitions given in US 202 -1 and the following definition shall apply:  
3.1 
polyester foam  
polyurethane foam formed by the reaction of a polyester resin with a polyisocyanate  DUS 202-4: 2015 
2 © UNBS  2015 – All rights reserved  
 4  Requirements  
4.1  General  
The foam shall be a polyester foam, shall be non -toxic, and shall be free from objectionable odour. The cell 
structure shall be such that it is acceptable and, in the cases of trimmed blocks, slabs, sheets, and shapes cut 
from any of these, the surfaces shall be smooth and free from cu ts, tears, and skins.  
4.2  Class and grade  
The class and the grade of a foam shall be one of the  combinations given in Table 1  
Table 1 — Classes and grades of foam  
1 2 3 
Class No.  Grade No.  Grade No.  
21 28 20 
23 28 20 
27 28 20 
33 28 20 
37 28 20 
4.3  Density and hardness  
The density of a foam and its hardness factor, determined (in both cases) in accordance with 7.4, shall be 
within t he appropriate limits given in T able 2.  
Table 2 — Density and hardness factor  
1 2 3 4 5 6 7 
Class  Density , kg/m3 Grade 
20 28 
Hardness factor  
min. max.  min. max.  min. max.  
21 - 21.0 17 23 26 30 
23 21.2 24.0 17 23 26 30 
27 24.1 29.0 17 23 26 30 
33 29.1 37.0 17 23 26 30 
37 37.1 - 17 23 26 30 
 
4.4  Flammability  
When a foam is tested in accordance with 7.4, 
a) no specimen s hall burn for 3 min or more  
b) no specimen shall burn beyond the gauge line.  DUS 202-4: 201 5 
© UNBS 2015 – All rights reserved  3 
 4.5  Other physical properties  
When tested in accordance with the relevant methods referred to in 7.4, a foam shall comply with the 
requirements given in T able 3, appropria te to the class and grade of the foam.  
 DUS 202-4: 201 5 
© UNBS 2015 – All rights reserved  1 
 Table 3 — Other physical properties  
1 2 3 4 5 6 7 8 9 10 11  
Property  Class   
21 23 27 33 37 
Grade  
28 20 28 20 28 20 28 20 28 20 
Compression set, %, max.  17.5 17.5 15 15 15 15 15 15 15 15 
Tensile Properties  
a) Tensile strength  i) Original, kPa, min.  80 80 80 80 80 80 80 80 80 80 
ii) After heat aging, retention of 
original, %, min.  80 80 80 80 80 80 80 80 80 80 
iii) After humid aging, retention 
of original, %, min.  80 80 80 80 80 80 80 80 80 80 
b) Elongation at break  i) Origi nal, kPa, min.  200 200 200 200 200 200 200 200 200 200 
ii) After heat aging, retention of 
original, %, min.  80 80 80 80 80 80 80 80 80 80 
iii) After humid aging, retention 
of original, %, min.  80 80 80 80 80 80 80 80 80 80 
Tear resistance , N/mm of width, min.   0.263  0.263 0.350 0.350 0.350 0.350 0.438 0.438 0.438 0.438  
Permanent resistance to solvents  i) visible deterioration (all 
solvents)  0* 0* 0* 0* 0* 0* 0* 0* 0* 0* 
ii) swelling, %  0 0 0 0 0 0 0 0 0 0 
iii) Tensile  strength  kPa, min.  80 80 80 80 80 80 80 80 80 80 
*  A change in colour shall not be construed as evidence of deterioration   
 DUS 202-4: 201 5 
© UNBS 2015 – All rights reserved  1 
 4.6  Shape and dimensions  
The foam shall be supplied in the form of blocks, trimmed blocks, slabs, or sheets cut from trimmed blocks, or 
other shapes cut from any of these form s. The size of blocks (nominal dimensions and the tolerances on 
those) shall be as specified by the purchaser or as required by the market. In the cases of trimmed blocks, 
slabs, sheets, and other shapes, the actual dimensions measured in accordance with 7 .3, shall not differ from 
the nominal values declared by more than the appropriate tolerances given in Table 4.  
Table 4 — Tolerances on dimensions (other than of blocks)  
1 2 3 
Magnitude of dimension, D, mm Tolerance  
mm( unless otherwise specified)  
Leng th  width  Thickness  
D ≤ 25    0                                              +3 
25 < D ≤ 150  0          +6.5  0          +6.5  0                                            +4.8  
151 < D ≤ 300  0          +12.5  0          +12.5  0                                            +6.5  
301 < D ≤ 600  0           +20  0           +20  0                                           +12.5  
601 < D ≤ 1000  0           +30  0           +30  0                                             +20  
1001 < D ≤ 1500  0           +30  0           +30  0                                             +30 
1501 < D ≤ 2000  0           +40  0           +40  0                                            +4 2 
D > 2000  0           +45  0           +45  0                                             +4 5 
5  Packing and marking  
5.1  Packing  
The foam shall be so packed that it is protected from dirt, gross distortion and nicking during normal transport 
and storage.  
5.2  Marking  
The following information shall appear in legible and indelible permanent marking on the outside of each 
packa ge on each piece of foam;  
a) name and address of manufacturer;  or importer or distributor and/ or trade mark  
b) batch number/ date of manufacture;  
c) dimensions;  
d) class and grade of foam and,  
e) country of origin. . DUS 202-4: 2015 
2 © UNBS  2015 – All rights reserved  
 6  Sampling and compliance criteria  
6.1 Sampling  
The following sampling procedure shall be applied in determining whether a lot complies with the 
requirements of the specification. The samples so taken shall be deemed to represent the lot.  
Take at random from the lot the number of samples shown in Column 2 of Table 5 relative to the appropriate 
lot size shown in Column 1. Each sample shall consist of the following:  
a) For inspection ― A complete piece.  
b) For testing ― Pieces of total volume of at least 0.01 m3. 
Table 5 — Sampling  
Size of lot, L, m3 Number of samples  
L ≤ 8  2 
8 < L ≤ 15  3 
15 < L ≤ 25  5 
25 < L ≤ 50  8 
50 < L ≤ 100  13 
 
6.2  Compliance criteria  
The lot s hall be deemed to comply with the specification if after inspection and testing of the samples taken in accordance 
with Clause 5, no defective is found  
7  Inspection and methods of test  
7.1  Inspection  
Visually examine and measure (using the method referre d to in 7.3) the samples taken for  inspection (see 5 ) 
for compliance with the requirements of 4.1, 4.6, and section 5. 
7.2  Conditioning  
Before testing, prepare and condition all specimens as in ISO 23529 . 
7.3  Dimensions  
The dimensions shall be measured i n accordance with ISO 1923 . 
7.4  Methods of test  
Use the relevant methods given in  Table 6  
 DUS 202-4: 201 5 
© UNBS 2015 – All rights reserved  3 
 Table 6: Properties and methods of test  
Property  Test methods  
Density  US ISO 845  
Hardness  factor   ISO 2439:2008, 7.3 method A  
Flammability  Annex B  
Compression  set ISO 1856  
Tensile strength and elongation at break  ISO 1793  
Fatigue resistance  ISO 3385  
Tear resistance  ISO 8067  
Resistance to solvent  Annex A  
 DUS 202-4: 2015 
4 © UNBS  2015 – All rights reserved  
 Appendix A 
(normative  references)  
 
 
Permanent resistance to solvents  
A.1  Apparatus  
A.1.1  Container  
a glass container large enough to allow complete immersion, without bending of a test specimen.  
A.1.2  Scoop  
a flat wire gauze scoop.  
A.1.3  Sinker  
a wire gauze sinker.  
A.1.4  Glass  
a square of plate glass.  
A.1.5  Measuring equipment  
as in Clause A.1.  
A.2  Reagents  
A.2.1  Petrol  
complying with the requirements of EAS US 158:2012  
A.2.2  Light -naphtha . 
A.2.3  Denatured alcohol . 
A.2.4  Trichloroethylene . 
A.3  Test specimen  
From the appropriate slab (see 5.1 b)), cut four specimens each of size at least 150 mm x 150 mm and of 
thickness approxima tely 10 mm  DUS 202-4: 201 5 
© UNBS 2015 – All rights reserved  5 
 A.4  Procedure  
Measure, as in Clause A.2 the thickness, length, and width of a specimen, and immerse it in one of the 
reagents in the container ensuring that it is totally submerged by covering it with the wire g auze sinker. After 
30 min, remove the sinker and, using the scoop, remove the specimen, and allow it to drain in the scoop for 5 
min. Then carefully transfer the specimen on to the glass plate, ensuring that the specimen is not distorted in 
any way during the transfer.  
Condition the assembly generally as in 6.2, but for at least 48 h or such longer period as may be necessary to 
ensure complete removal of the reagent, then re -measure the length, width, and thickness of the specimen 
and, disregarding any chan ge in colour, inspect the specimen for signs of visible deterioration.  
Then determine, as in Annex F, its tensile strength. Repeat the test with the other reagents, using a different 
specimen in each test.  
NOTE:  To avoid damage to the specimen, its thickne ss after immersion may be determined by measuring the total 
thickness of the assembly and deducting the thickness of the glass plate.  
A.5   Calculation and reporting  
For each reagent, calculate the swelling of the sample as follows:  
Swelling, % = 
100
1111 22
tata ta  
where,  
a1 = original area, in mm 2; 
a2 = area after immersion;  
t1= original thickness, in mm;  
t2 = thickness after immersion, in mm.  DUS 202-4: 2015 
6 © UNBS  2015 – All rights reserved  
 Appendix B  
(normative)  
 
Flammability  
B.1  Apparatus  
An apparatus as shown schematically in Figure G.1 and con sisting of a heat -resistant glass tube (chimney) in 
which a test specimen can be mounted, the base of the tube being connected to metered supplies of oxygen 
and nitrogen. The glass tube shall have a diameter of at least 75 mm and a height of at least 450 m m, and 
shall have at its base a bed of glass beads (or other inert particles) that will mix and distribute the incoming 
gases. The tube shall also contain a clamp that is capable of holding a test specimen (vertically) that the top of 
the specimen is at le ast 100 mm below the top of the tube.  
The oxygen and nitrogen used shall be of commercial grade (or better) and shall be supplied to the base of 
the glass tube through individual metering devices that enable the volumetric flow of each gas to be measured 
with an accuracy of 1 % or better.  
B.2  Test specimens  
From the appropriate slab ( see 5.1b)) cut five specimens each of size 12.5 mm + 0.5 mm x 12.5 mm + 0.5 mm 
x 130 mm and draw a gauge line across each specimen 75 mm from the end that is to be positioned 
uppermost in the apparatus.  
B.3  Procedure  
Clamp a test specimen in the holder of the apparatus so that it is held vertically in the centre of the glass 
chimney. Open the valves of the gas cylinders and adjust the flow so that the oxygen content of the gas  
mixture is 20 % + 0.2 % and that the flow rate up the glass chimney (as calculated from the volumetric flow 
rate divided by the cross -sectional area of the chimney) is 40 % + 10 % mm/s. Allow the gas to flow for at 
least 30 s and then, using a small gas f lame at the end of a tube, ignite the test specimen so that the whole of 
the upper surface is burning. Note whether the specimen burns for 3 min or longer and if not, whether or not 
the specimen has burned to below the 75 mm gauge line. Repeat the test wit h the remaining four specimens.  
 
Figure A.1 — General arrangement of flammability test apparatus  
 
 DUS 202-4: 201 5 
© UNBS 2015 – All rights reserved  7 
 Bibliography  
[1] SANS 641 Flexible polyurethane (polyester) foams  
 DUS 202-4: 2015 
© UNBS 2015– All rights reserved  9 
 Certification marking  
Products that conform to Uganda standards may be marked with Ugand a National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is governed by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licensed under the certif ication mark scheme operated by 
the Uganda National Bureau of Standards and in conjunction with the relevant Uganda Standard. The 
presence of this mark on a product or in relation to a product is an assurance that the goods comply with the 
requiremen ts of that standard under a system of supervision, control and testing in accordance with the 
certification mark scheme of the Uganda National Bureau of Standards. UNBS marked products are 
continually checked by UNBS for conformity to that standard.  
Furth er particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 DUS 202-4: 2015   
 
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