Reference number  
DRS 378 -1: 2017  
© RSB 2017  
 
 
 RWANDA 
STANDARD  DRS 
378-1 
 
First edition  
2017 -mm-dd 
 
Flexible polyurethane foam for mattresses 
— Specification — Part 1: General 
requirements  
 
  DRS 378 -1: 2017  
©RSB 2017 - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB 2017  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reprodu ce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 252 586103/ 582945  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  DRS 378 -1: 2017  
iii                ©RSB 2017 - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ .............................  v 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Requirements  ................................ ................................ ................................ ................................ .........  3 
4.1 General  ................................ ................................ ................................ ................................ ...................  3 
4.2 Class and grade  ................................ ................................ ................................ ................................ ..... 3 
4.3 Density and hardness factor  ................................ ................................ ................................ ................  3 
4.4 Colour  ................................ ................................ ................................ ................................ .....................  3 
4.5 Flammability  ................................ ................................ ................................ ................................ ...........  4 
4.6 Cell count  ................................ ................................ ................................ ................................ ...............  4 
4.7 Porosity  ................................ ................................ ................................ ................................ ..................  4 
4.8 Other physic al properties  ................................ ................................ ................................ .....................  4 
5 Packing and marking  ................................ ................................ ................................ ............................  1 
6 Sampling  ................................ ................................ ................................ ................................ ................  2 
7 Inspection and t est methods  ................................ ................................ ................................ ................  3 
7.1 Inspection  ................................ ................................ ................................ ................................ ...............  3 
7.2 Conditioning  ................................ ................................ ................................ ................................ ..........  3 
7.3 Preparation of test samples and test specimen  ................................ ................................ .................  3 
Annex  A (normative)  Dimensions  ................................ ................................ ................................ .....................  4 
A.1 General  ................................ ................................ ................................ ................................ ...................  4 
A.1 Apparatus  ................................ ................................ ................................ ................................ ...............  4 
A.2 Procedure  ................................ ................................ ................................ ................................ ...............  4 
Annex  B (normati ve)  Density  ................................ ................................ ................................ .............................  5 
B.1 Apparatus  ................................ ................................ ................................ ................................ ...............  5 
B.2 Test specimen  ................................ ................................ ................................ ................................ ........  5 
B.3 Procedur e ................................ ................................ ................................ ................................ ...............  5 
B.4 Calculation  ................................ ................................ ................................ ................................ .............  5 
Annex  C (normative)  Compression set  ................................ ................................ ................................ ............  6 
C.1 Apparatus  ................................ ................................ ................................ ................................ ...............  6 
C.2 Test specimens  ................................ ................................ ................................ ................................ ...... 6 
C.3 Procedure  ................................ ................................ ................................ ................................ ...............  6 
C.4 Calculation  ................................ ................................ ................................ ................................ .............  6 
Annex  D (norma tive)  Hardness factor  ................................ ................................ ................................ ..............  7 
D.1 Apparatus  ................................ ................................ ................................ ................................ ...............  7 
D.2 Test specimen  ................................ ................................ ................................ ................................ ........  7 
D.3 Procedure  ................................ ................................ ................................ ................................ ...............  7 
D.4 Calculation  ................................ ................................ ................................ ................................ .............  7 
Annex  E (normative)  Tensile properties  ................................ ................................ ................................ ..........  9 DRS 378 -1: 2017  
©RSB 2017 - All rights reserved                  iv 
 E.1 Apparatus  ................................ ................................ ................................ ................................ ............... 9 
E.2 Test specimens  ................................ ................................ ................................ ................................ ......9 
E.3 Procedure  ................................ ................................ ................................ ................................ ............... 9 
E.4 Calculations  ................................ ................................ ................................ ................................ ............ 9 
Annex  F (normative)  Tear resistance  ................................ ................................ ................................ .............  11 
F.1 Apparatus  ................................ ................................ ................................ ................................ ............  11 
F.2 Test specimens  ................................ ................................ ................................ ................................ ... 11 
F.3 Proced ure ................................ ................................ ................................ ................................ ............  11 
F.4 Calculation  ................................ ................................ ................................ ................................ ...........  11 
Annex  G (normative)  Flammability  ................................ ................................ ................................ ................  12 
G.1 Apparatus  ................................ ................................ ................................ ................................ ............  12 
G.2 Test specimens  ................................ ................................ ................................ ................................ ... 12 
G.3 Procedure  ................................ ................................ ................................ ................................ ............  12 
Annex  H (normative)  Tensile properties after heat aging  ................................ ................................ ...........  14 
Annex J (normative)  Tensile properties after humid aging  ................................ ................................ ........  15 
Annex K (normative)  Fatigue resistance  ................................ ................................ ................................ ...... 16 
K.1 Apparatus  ................................ ................................ ................................ ................................ ............  16 
K.2 Test specimen  ................................ ................................ ................................ ................................ ..... 16 
K.3 Proced ure ................................ ................................ ................................ ................................ ............  16 
K.4 Calculation  ................................ ................................ ................................ ................................ ...........  16 
Annex M  (normative)  Permanent resistance to solvents ................................ ................................ ............  17 
M.4 Procedure  ................................ ................................ ................................ ................................ ............  17 
M.5 Calculation and reporting  ................................ ................................ ................................ ..................  18 
Annex P  (normative)  Porosity  ................................ ................................ ................................ .......................  20 
. DRS 378 -1: 2017  
v                ©RSB 2017 - All rights reserved  
 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratifie d by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 378-1 was prepared by Technical Committee RSB/TC 024, Chemicals and Consumer Products  
In the preparation of this standard, reference was made to the following st andard  : 
1) EAS 7 -1, Flexible polyurethane foam for mattresses — Specification — Part 1: General requirements  
The assistance de rived from the above source is hereby acknowledged with thanks.  
DRS 378  consists of the following parts, under the general title Flexible polyurethane foam for mattresses — 
Specificati on: 
DRS 378-1 Flexible polyurethane foam for mattresses — Specification — Part 1: General requirements  
DRS 378-2 Flexible polyurethane foam for mattresses — Specification — Part 2: Mattresses   
DRS 378-3, Flexible polyurethane foam for mattresses — Specification — Part 3: Reconstituted flexible 
polyurethane foam  
Committee membership  
The following organizations were represented on the Technical Committee on Chemicals and Consumer 
Products (RSB/TC 024) in the preparation of this standard.  
Paragraph of p articipants  
Rwanda  Standards Board (RSB) – Secretariat  
 DRS 378 -1: 2017  
1                ©RSB 2017 - All rights reserved  
 Flexible polyurethane foam for mattresses — Specification  — Part 1: 
General requirements  
1 Scope  
This Part 1 of this draft Rwanda  Standard  covers the requirements for eight classes (based on density) of 
flexible  polyurethane foams of the poly ether type, in t he form of blocks, slabs, sheets, and shapes cut from 
these. Each class is sub -divided, according to the hardness of the foam, into at least four grades.  
2 Normative references  
The following documents are referred to in the text in such a way that some or al l of their content constitutes 
requirements 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.  
DRS 378-2, Flexible polyurethane f oam for mattresses — Specification — Part 1: Mattresses  
DRS 378-3, Flexible polyurethane foam for mattresses — Specification — Part 3: Reconstituted flexible 
polyurethane foam  
REAS 158, Gasoline (petrol) unleaded — Specification  
3 Terms and definitions  
For the purposes of this standard, the follow ing terms and definitions apply   
3.1 
block  
mass of polyurethane foam formed by a free -rising foam process, in its or iginal form prior to conversion  
3.2 
defective  
foam that fails in one or more respects to comply with the relevant requirements of the specification  
3.3 
polyurethane  foam  
  
foam in which the polyol component is a polyether.  It is a cellular material produced by the reaction of the 
polyol with an organic isocyanate in the presence of water and  that may include catalysts, surface active 
agents, auxiliary blowing agents, fillers, plasticizers, colourants and any other additives that do not adversely 
affect the properties of the foam.  Industrial synonyms are “log”, “bun”, “loaf”, “slab stock”   
©RSB 2017 - All rights reserved                  2 
 3.4 
lot 
not less than 1 m3 and not more than 100 m3 of  foam of the same class, grade, and nominal dimensions, from 
one manufacturer, submitted at any one time for inspection and testing  
3.5 
linear dimension  
linear measurements of a specimen in different dire ctions expressed in millimetres  
3.6 
density  
the mass per unit volume of the foam specimen at 23  2 °C expressed in kg/m3 
3.7 
tensile strength  
the stress at the breaking point of a specimen expressed in kgf/cm2 
3.8 
tensile stress  
the stress at predetermine d elongation of a specimen expressed in kgf/cm2 
3.9 
ultimate elongation (elongation at break)  
percentage strain produced in a specimen stretched to its breaking point  
3.10 
hardness number  
it is stated in the form of grading and is numerically equal to the compressive stress which is necessary to 
penetrate the specimen without puncture to a specified depth or deflection expressed as the load (kgf) per unit 
area of compression (cm2). Hardness number at 40 % or 50 % deflection on specific thickness of sample i s 
also referred to as hardness index  
3.11 
indentation hardness index  
load required to produce a depression of 40 % of initial thickness of the sample  DRS 378 -1: 2017  
3                ©RSB 2017 - All rights reserved  
 3.12 
load quotient (indentation hardness characteristic)  
ratio of hardness number at two specified deflections, namely, 65 % and 25 %  
4 Requirements  
4.1 General  
Foam shall be polyether 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 cuts, tears, and skins.  
4.2 Class and grade  
The class and the grade of foam shall be one of the combinations given in Table 1.  
Table 1 — Classes and grades of foam  
Class  
No Grade  
No Grade  
No Grade  
No Grade  
No Grade  
No Grade  
No 
1 2 3 4 5 6 7 
17 6 9 12 16 - - 
20 6 9 12 16 - 24 
23 6 9 12 16 20 24 
26 6 9 12 16 20 24 
30 6 9 12 16 20 24 
36 - 9 12 16 20 24 
44 - 9 12 16 20 24 
48 - - 12 16 20 24 
 
4.3 Density and hardness factor  
The density of foam , determined in accordance with Annex B, and its hardness factor, determined in 
accordance with Annex D, shall be within the appropriate limits given in Table 2.  
4.4 Colour  
The colours of foam shall be as follows:  
a) Light duty — White or blue   
©RSB 2017 - All rights reserved                  4 
 b) Medium duty — Grey  
c) Heavy duty — Red, pink or violet  
d) Super heavy duty — Green  
4.5 Flammability  
When foam is tested in accordance with Annex G,  
a) no specimen shall burn for 3 min or more; and  
b) no specimen shall burn beyond the gauge line.  
4.6 Cell count  
The number of cells % per centimetre of foam, determined in accordance with Annex M shall not exceed the 
limit specified by the purchaser.  
4.7 Porosity  
When the porosity of foam is specified by the purchaser, the foam, when tested in accordance with Annex N, 
shall permit th e flow of air at the rate so specified.  
4.8 Other physical properties  
When tested in accordance with the relevant methods given in the Annexes, foam shall comply with the 
requirements given in Table 3 appropriate to the class and grade of the foam.  
Table 2 — Density and hardness factor  
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 
 
Class   
Density, 
kg/m3 Grade  
6 9 12 16 20 24 
Hardness factor  
Min. Max.  Min
. Max.  Min. Max.  Min. Max.  Min. Max.  Min. Max.  Min. Max.  DRS 378 -1: 2017  
5                ©RSB 2017 - All rights reserved  
  
17 
 
20 
 
23 
 
26 
 
30 
 
36 
 
44 
 
48  
15 
 
17.6 
 
21.1 
 
24.1 
 
27.1 
 
32.1 
 
40.1 
 
48.1  
17.5 
 
21.0 
 
24.0 
 
27.0 
 
32.0 
 
40.0 
 
48.0 
 
-  
3.6 
 
3.6 
 
3.6 
 
3.6 
 
3.6 
 
- 
 
- 
 
-  
7.2 
 
7.2 
 
7.2 
 
7.2 
 
7.2 
 
- 
 
- 
 
-  
7.2 
 
7.2 
 
7.2 
 
7.2 
 
7.2 
 
7.2 
 
7.2 
 
-  
10.8 
 
10.8 
 
10.8 
 
10.8 
 
10.8 
 
10.8 
 
10.8 
 
-  
10.8 
 
10.8 
 
10.8 
 
10.8 
 
10.8 
 
10.8 
 
10.8 
 
10.8  
14.4 
 
14.4 
 
14.4 
 
14.4 
 
14.4 
 
14.4 
 
14.4 
 
14.4  
14.4 
 
14.4 
 
14.4 
 
14.4 
 
14.4 
 
14.4 
 
14.4 
 
14.4  
18.0 
 
18.0 
 
18.0 
 
18.0 
 
18.0 
 
18.0 
 
18.0 
 
18.0  
- 
 
- 
 
18.0 
 
18.0 
 
18.0 
 
18.0 
 
18.0 
 
18.0  
- 
 
- 
 
21.6 
 
21.6 
 
21.6 
 
21.6 
 
21.6 
 
21.6  
- 
 
- 
 
21.6 
 
21.6 
 
21.6 
 
21.6 
 
21.6 
 
21.6  
- 
 
- 
 
25.2 
 
25.2 
 
25.2 
 
25.2 
 
25.2 
 
25.2 
 DRS 378 -1: 2017  
1                ©RSB 2017 - All rights reserved  
 Table 3 — Other physical properties  
1 2 3 4 5 6 7 8 9 10 11 
 
Property  Class  
17 20 23 
Grade  
6 9 12 16 6 9 12 16 6 9 
Compression set, %, max.  
 
Tensile properties  
Tensile strength  
Original, kPa, min.  
ii)    After heat aging, retention of original, %, 
min.  
After humid aging, retention of original, %, min.   
 
b)   Elongation at break  
Original, %, min.   
After heat aging, retention of original, %, min.   
After humid aging, retention of original, %, min.  
 
Tear resistance,  N/mm of width, min.  
 
Permanent resistance to solvents  
Visible deterioration (all solvents)  
Swelling, %   
Tensile strength, retention of original, %, min.   
 
Fatigue resistance  15 
 
 
 
59 
80 
80 
 
 
100 
40 
40 
 
0.175  
 
 
 
 
90 
 
 15 
 
 
 
69 
80 
80 
 
 
100 
40 
40 
 
0.219  
 
 
 
 
90 
 
 15 
 
 
 
69 
80 
80 
 
 
100 
40 
40 
 
0.219  
 
 
 
 
90 
 
 15 
 
 
 
69 
80 
0 
 
 
100 
40 
40 
 
0.219  
 
 
 
 
90 
 
 12 
 
 
 
69 
80 
80 
 
 
100 
40 
40 
 
0.219  
 
 
Nil 
Nil 
90 
 
 12 
 
 
 
69 
80 
80 
 
 
100 
40 
40 
 
0.263  
 
 
 
 
90 
 
 12 
 
 
 
69 
80 
80 
 
 
100 
40 
40 
 
0.263  
 
 
 
 
90 
 
 12 
 
 
 
69 
80 
80 
 
 
100 
40 
40 
 
0.263  
 
 
 
 
90 
 
 10 
 
 
 
69 
80 
80 
 
 
100 
40 
40 
 
0.263  
 
 
 
 
90 
 
 10 
 
 
 
83 
80 
80 
 
 
100 
40 
40 
 
0.350  
 
 
 
 
90 
 
  
©RSB 2017 - All rights reserved                  2 
 Retention of hardness factor, %, min.  
Loss in height, %, max.   60 
5 60 
5 60 
5 60 
5 60 
5 60 
5 60 
5 60 
5 70 
4 70 
4 
NOTE  A change in colour shall not be construed as evidence of deterioration.  
 
Table 3 (continued)  
1 2 3 4 5 6 7 8 9 10 11 
 
Property  Class  
23 26 
Grade  
12 16 20 24 6 9 12 16 20 24 
Compression set, %, max.  
 
Tensile properties  
 Tensile strength  
Original, kPa, min.  
After heat aging, retention of original, %, min.  
iii)   After humid aging, retention of original, %, min.   
 
 Elongation at break  
Original, %, min.   
After heat aging, retention of original, %, min.   
After humid aging, retention of original, %, min.    
 
Tear resistance,  N/mm of width, min.  
 10 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 10 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 10 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 10 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 9 
 
 
 
69 
80 
 
80 
 
 
100 
40 
 
40 
 9 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 9 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 9 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 9 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 9 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 DRS 378 -1: 2017  
3                ©RSB 2017 - All rights reserved  
 Permanent resistance to solvents  
Visible deterioration (all solvents)   
ii)   Swelling, %   
iii)  Tensile strength, retention of original, %, min.   
 
Fatigue resistance  
i)   Retention of hardness factor, %, min.  
ii)  Loss in height, %, max.   0.350  
 
 
 
 
90 
 
 
70 
4 0.50 
 
 
 
 
90 
 
 
70 
4 0.350  
 
 
 
 
90 
 
 
70 
4 0.350  
 
 
 
 
90 
 
 
70 
4 0.263  
 
 
Nil 
Nil 
90 
 
 
75 
3 0.350  
 
 
 
 
90 
 
 
75 
3 0.350  
 
 
 
 
90 
 
 
75 
3 0.350  
 
 
 
 
90 
 
 
75 
3 0.350  
 
 
 
 
90 
 
 
75 
3 0.350  
 
 
 
 
90 
 
 
75 
3 
 
   
©RSB 2017 - All rights reserved                  4 
 Table 3 (continued)  
1 2 3 4 5 6 7 8 9 10 11 12 
 
Property  Class  
30 36 
Grade  
6 9 12 16 20 24 9 12 16 20 24 DRS 378 -1: 2017  
5                ©RSB 2017 - All rights reserved  
 Compression set, %, max.  
 
Tensile properties  
Tensile strength  
Original, kPa, min.  
ii)    After heat aging, retention of original, %, min.  
After humid aging, retention of original, %, min.   
 
Elongation at break  
Original, %, min.   
ii)    After heat aging, retention of original, %, min.  
iii)   After humid aging, retention of original, %, min.   
 
Tear resistance,  N/mm of width, min.  
 
Permanent resistance to solvents  
i)    Visible deterioration (all solvents)   
ii)   Swelling, %   
iii)  Tensile strength, retention of original, %, min.   
 
Fatigue resistance  
i)    Retention of hardness factor, %, min.  
ii)   Loss in height, %, max.   8 
 
 
 
69 
80 
 
80 
 
 
100 
40 
 
40 
 
0.263  
 
 
 
 
90 
 
 
77.5 
2.5 8 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
77.5 
2.5 8 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
77.5 
2.5 8 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
77.5 
2.5 8 
 
 
 
97 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
Nil 
Nil 
90 
 
 
77.5 
2.5 8 
 
 
 
97 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
  6 
 
 
 
69 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
80 
2 6 
 
 
 
69 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
80 
2 6 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
80 
2 6 
 
 
 
97 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
80 
2 6 
 
 
 
97 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
80 
2 
 
  
©RSB 2017 - All rights reserved                  6 
 Table 3 (continued)   
1 2 3 4 5 6 7 8 9 10 
 
Property  Class  
44 48 
Grade  
9 12 16 20 24 12 16 20 24 DRS 378 -1: 2017  
7                ©RSB 2017 - All rights reserved  
 Compression set, %, max.  
 
Tensile properties  
 Tensile strength  
i)     Original, kPa, min.  
ii)    After heat aging, retention of original, %, min.  
iii)   After humid aging, retention of original, %, min.   
 
Elongation at break  
i)    Original, %, min.   
ii)   After heat aging , retention of original, %, min.   
iii)   After humid aging, retention of original, %, min.   
 
Tear resistance,  N/mm of width, min.  
 
Permanent resistance to solvents  
i)    Visible deterioration (all solvents)  
ii)   Swelling, %   
iii)  Tensile strength, retention of original, %, min.   
 
Fatigue resistance  
i)    Retention of hardness factor, %, min.  
ii)   Loss in height, %, max.  5 
 
 
 
69 
80 
 
80 
 
 
100 
40 
 
40 
 
0.263  
 
 
 
 
90 
 
 
82.5 
2 5 
 
 
 
69 
80 
 
80 
 
 
100 
40 
 
40 
 
0.263  
 
 
 
 
90 
 
 
82.5 
2 5 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
82.5 
2 5 
 
 
 
97 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
Nil 
Nil 
90 
 
 
82.5 
2 5 
 
 
 
97 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
82.5 
2 4 
 
 
 
83 
80 
 
80 
 
 
100 
40 
 
40 
 
0.263  
 
 
 
 
90 
 
 
85 
1.5 4 
 
 
 
97 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
85 
1.5 4 
 
 
 
118 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
85 
1.5 4 
 
 
 
118 
80 
 
80 
 
 
100 
40 
 
40 
 
0.350  
 
 
 
 
90 
 
 
85 
1.5 DRS 378 -1: 2017  
1                ©RSB 2017 - All rights reserved  
  
4.9 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 forms, and the actual dimensions, measured in accordance with 7.3 shall 
not differ from the nominal values by more than the appropriate tolerances given in Table 4.  
Table 4 — Tolerances on dimensions (other than of blocks)  
 Length and width  Thickness  
         
               D             25 
 
      25  < D           150 
          
   151  <  D          300 
 
   301  <  D           600 
 
   601  <  D        1 000  
       
   1 000 <D       1 500  
 
   1 501< D       2 000  
 
               D    >   2 000   
- 5 %  + 10 %  
 
           - 0 +  6.5  
 
           - 0 +  6.5  
 
           - 0 + 12.5  
 
            - 0 + 20  
 
            - 0 + 30  
 
            - 0 + 40  
 
            - 0 + 45   
- 5 % + 10 %  
 
                 - 0 +  4.8  
 
- 0  +  6.5  
  
 - 0 + 12.5  
 
- 0 + 20  
 
                 - 0 + 30  
  
- 0 + 420  
 
                 - 0 + 45  
 
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 durable marking on the outside of each package on each 
piece of foam:  
a) name and address of manufacturer;   
©RSB 2017 - All rights reserved                  2 
 b) lot or batch number;  
c) dimensions;  
d) class and grade  of foam;  
e) made in Kenya/country of origin.  
6 Sampling  
6.1 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 at le ast 0.01 m3.  
Table 5 — Sampling  
Size of lot, L, m3 Number of samples  
1 2 
L   8 2 
8      <    L   l5 3 
15    <    L  25 5 
25    <    L  50 8 
50    <    L  l00 13 
 
6.2 Compliance with the specification  
The lot shall be deemed to comply with the specification if after inspection and testing of the samples taken in 
accordance with  Clause  6, no defective is found.  DRS 378 -1: 2017  
3                ©RSB 2017 - All rights reserved  
 7 Inspection and test methods  
7.1 Inspection  
Visually examine and measure (using the method given in Annex A) the samples ( see 6.1 (a)) for 
compliance with the requirements of 6.1, 4.8, 4.9, and Clause 5.  
7.2 Conditioning  
Before testing, maintain all specimens for at least 16 h in an atmosphere having a relative humidity of wise 
65 ± 2 % and a temperature of 23 ± 2 °C.  
7.3 Preparation o f test samples and test specimen  
7.3.1  From each sample obtain, as follows, a test sample for each test given in the Annexes.  
Using a fine -toothed saw or rotary slicer (but not a heated wire), cut across the direction of rise of the foam (as 
determined by microscopical examination) a slab of suitable size and of the same thickness as that of the test 
specimens required for the relevant test, and that is free from skin.  
NOTE  Slabs of the following thickness are required: 12.5 mm, 25 mm, 50 mm.  
7.3.2  When cut ting the test specimens (Annexes B, C and M), use a die, a saw, or a knife, as appropriate, 
and ensure that the top and bottom surfaces of each specimen are flat and parallel to each other, that the 
sides are vertical, and that the test specimens are free from skin.   
©RSB 2017 - All rights reserved                  4 
 Annex  A 
(normative)  
 
Dimensions  
A.1 General  
A.1 Apparatus  
A.1.1  Metre rule , a steel rule graduated in millimetres and accurate to 1 mm (or better).  
A.1.2  Micrometer , a micrometer accurate to 0.01 mm (or better) with a presser foot of area at least 6.5 cm 
and capable of exerting a pressure of 100 + 10 Pa.  
A.2 Procedure  
Measure the dimensions of each sample (using the rule for dimensions greater than 30 mm and the 
microme ter for dimensions not exceeding 30 mm).  
 
 
 
 
 
 
 
 
 
 
 DRS 378 -1: 2017  
5                ©RSB 2017 - All rights reserved  
 Annex  B 
(normative)  
 
Density  
B.1 Apparatus  
B.1.1  Balance , a balance having a sensitivity of 0.1 g (or better).  
B.1.2  Measurement,  as in A.1.  
B.2 Test specimen  
The test specimen may be of any size or shape provided that  its volume is at least 500 cm3 and can easily be 
calculated from its linear dimensions, and that the specimen is cut from the full thickness of the sample.  
B.3 Procedure  
a) Determine the mass of the specimen.  
b) Measure the dimensions of the specimen by the method described in Annex A and calculate its volume.  
B.4 Calculation  
Calculate the density of the specimen as follows:  
 
001vD      M        
where,  
 D density, in kg/m3; 
 M mass, in g;  
 V volume, in cm3. 
 
  
©RSB 2017 - All rights reserved                  6 
 Annex  C 
(normative)  
 
Compression set  
C.1 Apparatus  
C.1.1  Jig, a comp ression set jig consisting of two rigid steel plates each of size at least 100 mm x 60 mm, 
held parallel to each other by means of bolts and held 6.25 mm apart by means of metal spacers.  
C1.2  Oven , an air -circulating oven maintained at 70 °C.  
C.2 Test specimen s  
From the appropriate slab ( see 6.1 (b) cut three rectangular test specimens 50 mm x 50 mm x 25 mm.  
C.3 Procedure  
Measure as in Annex A the thickness of each specimen. Place a specimen in the jig, compress it from 25 mm 
to a thickness of 6.25 mm and, within  15 min, place the assembly in the oven for 22 h. Remove the assembly 
from the oven, remove the specimen from the compression set device, allow the specimen to recover for a 
period of 35 ± 5 min, and then measure the thickness. Repeat the test on the remai ning specimens.  
C.4 Calculation  
Calculate the compression set of each specimen as follows:  
Compression set, %     =  
100
oc o
ttt                
 where,  
to   =   the original thickness of test specimen, in mm;  
tc   =   the final thickness of test specimen, in mm.  
Record the mean of the three results as the compression set of the sample.  
 
 DRS 378 -1: 2017  
7                ©RSB 2017 - All rights reserved  
 Annex  D 
(normative)  
 
Hardness factor  
D.1 Apparatus  
A machine consisting of a flat circular indentor foot of thickness 10 mm, having the bottom edge rounded to a 
radius of 1  mm and a contact area of 322.5 cm2, and that can be raised or lowered at a speed of 100 ±  20 mm 
min and a base -plate that has 6.0 mm diameter perforations at 20 mm centres. The indentor foot is connected 
through a swivel joint to two gauges, one of which is capable of recording the force exerted by the foot upon 
the specimen and the other the distance travelled, relative to the base -plate.  
D.2 Test specimen  
From the appropriate slab ( see 6.1(b)) cut one recta ngular specimen of size 380 mm x 380 mm x 50 mm. Fo r 
a sample of thickness less than 50 mm, specimens of thickness at least 15 mm mav be plied together (without 
the use of an adhesive) to give a total thickness of 50 mm.  
D.3 Procedure  
Place the specimen centrally under the indicator foot and lower the foot in to contact with the specimen and 
record the distance between the foot and the base -plate.  Flex the specimen twice by lowering the foot 35 mm 
then allow the specimen to recover for 10 min under no load.  
Lower the foot until a force of 5 N is recorded on the gauge, record the distance travelled, and calculate, as 
follows, the thickness of the specimen under this load ( TL): 
TL = A ― B  
where,   
TL thickness of specimen, under load, in millimeters (mm)  
A the distance of the foot from the base -plate before flex ing, in mm;  
B the distance travelled by foot, in mm.  
Then lower the foot until the specimen is compressed to 60 % of its calculated thickness and note the force 
recorded on the gauge after 60  s. 
D.4 Calculation  
Calculate, as follows, the hardness factor HF of the specimen, and record this value as the hardness factor of 
the sample:   
©RSB 2017 - All rights reserved                  8 
 HF = 0.102 × F 
where  
HF is the force, in newtons required to produce 40 % compression.  
Report the value as the hardness factor.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DRS 378 -1: 2017  
9                ©RSB 2017 - All rights reserved  
 Annex  E 
(normative)  
 
Tensile properties  
E.1 Apparatus  
E.1.1  Tensile -strength testing machine , a tensile -strength testing machine of the self -aligning type, and 
of size and design suitable for breaking the test specimens under a tensile load. The speed of the moving 
beam shall be 500 ± 50 mm/min. The  machine shall be equipped with an indicator that records the maximum 
force applied during the test and with jaws that so clamp the specimens that they will not slip during testing.  
E.1.2  Micrometer , accurate to 0 .01 mm (or better) with a presser foot of a rea at least 6 .5 cm2 and capable 
of exerting a pressure of 100 Pa ± 10 Pa.  
E.1.3  Die, a steel die of the shape and dimensions given in, Figure E.1.  
E.1.4  Steel rule , graduated in millimetres and accurate to 1 mm (or better).  
E.2 Test specimens  
From the appropriate slab ( see 6.1(b)) cut using the dies five specimens each of thickness of at least 12.5 
mm, and mark the gauge length ( see Figure E.1) on each specimen.  
E.3 Procedure  
Accurately measure the thickness and the width of a test specimen at three points  equally spaced along the 
gauge length.  Then so clamp the ends of the specimen in the jaws of the machine that the distance between 
the jaws is 90 ± 5 mm, operate the machine until the specimen ruptures and record the maximum force 
applied and the distanc e between the reference lines at rupture. Repeat the test on the remaining four test 
specimens.  
E.4 Calculations  
E.4.1  Calculate the average cross -sectional area of the narrow section of each test specimen, and then 
calculate its tensile strength TS as follows : 
TS = 1000 × 
AFmax  
Where  
TS is the tensile strength, in kilopascals (kPa);   
©RSB 2017 - All rights reserved                  10 
 Fmax is the maximum force applied, in newtons (N);  
A is the average cross -sectional area, in millimetres cubed (mm2). 
Record the average of the five results as the tensile strength of the sample.  
E.4.2  Calculate the elongation at break of each test specimen as follows:  
100      
b 
oo
LLLE
 
where,  
Eb is elongation at break, in percentage (%);    
L is the distance between the reference lines at rupture, in millim etres (mm);  
Lo is the original distance between the reference lines, in millimetres (mm).  
Record as the elongation at break of the sample the mean of the five results.  
 
 
Figure E.1 — Steel die  
 
 
 
 
DRS 378 -1: 2017  
11                ©RSB 2017 - All rights reserved  
 Annex  F 
(normative)  
 
Tear resistance  
F.1 Apparatus  
F.1.1  Tensile -strength testing machine, of the self -aligning type, and of size and design suitable for breaking the 
test specimens under a tensile load. The speed of the moving beam shall be (50 ± 50) mm/min. The machine shall be 
equipped with an indicator that records the maximum force applied during the test and with jaws that so clamp the 
specimens that they will not slip during testing.  
F.1.2  Micrometer, accurate to 0 .01 mm (or better) with a presser foot of area at least 6 .5 cm2 and capable of 
exerting a pre ssure of 100 Pa ± 10 Pa.  
F.2 Test specimens  
From the appropriate slab ( see 6.1(b)) cut five specimens each of size 150 mm × 25 mm × 25 mm. By cutting 
longitudinally as in Figure F.1 down the centre of each specimen, form two tongues of length 40 mm.  
F.3 Procedure   
Using the micrometer, measure the width of the specimen, and then clamp the tongues in the jaws of the 
machine. Operate the machine, ensuring that the tear propagates through the centre of the specimen (by 
nicking with a razor blade, if necessary), until  the specimen is torn for a distance of at least 50 mm , and note 
the maximum force recorded during the test. Repeat the test on the other four specimens.  
F.4 Calculation  
Calculate the tear resistance of each specimen TR as follows:  
TR = 
WFmax  
where 
TR is the tear resistance, in newtons per millimetre of width (N/mm);  
Fmax is the maximum force applied, in newtons (N);  
W is the width of the specimen, in millimetres (mm).  
Report the mean tear resistance of the five specimens as the tear resistanc e of the sample.   
©RSB 2017 - All rights reserved                  12 
 Annex  G 
(normative)  
 
Flammability  
G.1 Apparatus  
An apparatus as shown  schematically in Figure G.1 and consisting 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 mm, 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 sh all also contain a clamp that is capable of holding a test specimen (vertically) that the top of 
the specimen is at least 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 b ase 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.  
G.2 Test specimens  
From the appropriate slab ( see 6.1(b)) cut five specimens each of size 12.5 ± 0.5 mm × 1 2.5 ± 0.5 mm × 130 
mm and draw a gauge line across each specimen 75 mm from the end that is to be positioned uppermost in 
the apparatus.  
G.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 flame 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 with the remaining four specimens.  
 
 
 
 DRS 378 -1: 2017  
13                ©RSB 2017 - All rights reserved  
  
Figure G.1 — General arrangement of flammability test apparatus  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
©RSB 2017 - All rights reserved                  14 
 Annex  H 
(normative)  
 
Tensile properties after heat aging  
Determine as in Annex F  the tensile strength and elongation at break of five specimens that have been heat 
aged for 22 h in an air oven at 140 ºC ± 1 ºC.   
Calculate the resistance to heat aging Aheat of the sample as follows:  
Aheat = 
tsts 100aged  
where  
Aheat is the resistance to heat aging, expressed as a ratio of tensile strengths, as a percentage (%);  
tsaged is the tensile strength of the heat aged sample, in kilopascals (kPa);  
ts is the original tensile strength, in kilopa scals (kPa).  
 
  DRS 378 -1: 2017  
15                ©RSB 2017 - All rights reserved  
 Annex I 
(normative)  
 
Tensile properties after humid 
aging  
Determine as in Annex F the tensile strength and elongation at break of five specimens that have been humid 
aged in dry steam at 105 ºC ± 1 ºC for 3 h, dried at 70 ºC to constant mas s, and conditioned as in 7.2.  
Calculate the resistance to humid aging of the sample as follows:  
tstsA100aged
humid
 
Ahumid is the resistance to humid aging, expressed as a ratio of tensile strengths, as a percentage (%);    
tsaged is the tensile strength of the humid aged sample, in kilopascals (kPa);  
ts is the original tensile strength, in kilopascals (kPa).  
 
 
 
 
 
 
 
 
 
 
  
©RSB 2017 - All rights reserved                  16 
 Annex J 
(normative)  
 
Fatigue resistance  
K.1 Apparatus  
K.1.1 Flexing machine , that consists of two rigid parallel plates, 50 mm apart, the upper plate being 
capable of so oscillating through a distance of 37 .5 mm at a frequency of one cycle per second as to 
compress the specimen to 25 % of its unstressed thickness. The bottom plate has 6 mm diameter perforations 
at 20  mm centres and the size of each plate shall be at least 400 mm × 400 mm.   
K.1.2 Steel rule , graduated in millimetres and accurate to 1 mm (or better).  
K.2 Test specimen  
From the appropriate slab (see 6.1(b)), cut one rectangular specimen of size 380 mm × 380 mm × 50 mm. For 
a sample of thickness less than 50 mm, specimens of thickness at least 15 mm may be plied together (without 
the use of an adhesive) to give a total thickness of 50 mm.   
K.3 Procedure  
Determine the hardness factor as in D.4, then plac e the specimen between the plates of the flexing machine 
and subject it to 100 000 flexing cycles. Remove the specimen, allow it to recover for 30 min, measure the 
height of the specimen, and then redetermine its hardness factor.   
K.4 Calculation  
Calculat e the retention of hardness factor Aflex of the sample as follows:  
100flex
flexhfhfA
 
where  
Aflex is the retention of hardness factor, in percentage (%);    
hfflex is the hardness factor after flexing;    
hf is the hardness factor before flexing.   
Calculate also the percentage loss in height of the specimen  DRS 378 -1: 2017  
17                ©RSB 2017 - All rights reserved  
 Annex K 
(normative)  
 
Permanent resistance to solvents  
M.1 Apparatus  
M.1.1 Glass container , large enough to allow complete immersion, of a test specimen, without bending.   
M.1.2 Flat wire gauze scoop  
M.1.3 Wire gauze sinker  
M.1.4 Square of plate glass  
M.1.5 Measuring equipment , as in A.1.   
M.2 Reagents  
M.2.1 Petrol , complying with the requirements of EAS 158 .   
M.2.2 Light naphtha  
M.2.3 Denatured alcohol  
M.2.4 Trichloroethylene  
M.3 Test specimen  
From the appropriate slab (see 6.1( b)), cut four specimens each of size at least 150 mm × 150 mm and of 
thickness approximately 10 mm.  
M.4 Procedure  
Measure, as in 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 gauze 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 as in 7.2, but for at leas t 48 h or such longer period as may be necessary to ensure 
complete removal of the reagent. Remeasure the length, width, and thickness of the specimen and, 
disregarding any change in colour, inspect the specimen for signs of visible deterioration. Then det ermine its 
tensile strength as in Annex F.   
©RSB 2017 - All rights reserved                  18 
 Repeat the test with the other reagents, using a different specimen in each test.  
NOTE  To avoid damage to the specimen, its thickness after immersion should be determined by measuring the total thickness of the 
assembly and deducting the thickness of the glass plate.  
M.5 Calculation and reporting  
For each reagent, calculate the swelling S of the sample as follows:  
100
1111 22tatataS
 
where    
S is the swelling, as a percentage (%);    
a1 is the original area, i n square millimetres (mm2);    
a2 is the area after immersion, in square millimetres (mm2);    
t1 is the original thickness, in millimetres (mm);    
t2 is the thickness after immersion, in millimetres (mm).  
 
 
 
 
 
 DRS 378 -1: 2017  
19                ©RSB 2017 - All rights reserved  
  
Annex L 
(normative)  
 
Cell count  
N.1 Apparatus  
A thread counter consisting of a lens of 5 times magnifying power mounted over a base plate that contains a 
rectangular aperture of accurately known length. The mass of the thread counter must be sufficiently low (or 
the thread counter must be so  supported) as not to deform the specimen.  
N.2 Test specimens  
From each sample cut (see 6.1(b)) three specimens each of size 100 mm × 100 mm.  
N.3 Procedure  
Place the thread counter on the test specimen, count the number of cells intersected by one of the edges of 
the aperture, and calculate the number of cells per lineal centimetre. Repeat the test on the remaining two 
specimens and record the average of the three values obtained as the cell count of the sample.  
 
 
 
 
 
 
  
©RSB 2017 - All rights reserved                  20 
 Annex M 
(normative)  
 
Porosity  
P.1 Apparatus  
The apparatus consists, essentially, of a specimen holder connected through a flow meter to a supply of clean 
dry air. The apparatus shall include means for precise control of air flow rate and a manometer connected 
between the specimen holder an d the flow meter. The specimen holder shall consist of  a circular container, of 
internal diameter 38 mm and depth 25 mm, that has an air inlet of diameter 25 mm in the centre of its base, 
and a cover with a central aperture of diameter 25 mm. The cover sh all form an airtight seal with the top of the 
container, and the entire apparatus shall be free from leaks.  
P.2 Test specimens  
From the appropriate slab (see 6.1( b)) cut four cylindrical specimens each of diameter 38 mm and height 25 
mm.  
P.3 Procedure  
Level the manometer and set it at zero. Insert the test specimen holder and replace the cover. Turn on the air 
supply and adjust it to obtain a pressure in the apparatus (as recorded by the manometer) of 125 Pa. When 
the pressure reading is steady, note the r ate of air flow recorded by the flow meter. Repeat the test with the 
remaining three specimens.  
Calculate the porosity of each specimen as follows:  
Porosity, m3/s.m2  =  2 040 F  
where,  
F   =   the flow rate, in m3 / s. 
Record the mean of the four results  as the porosity of the sample.  
 
 
 
 
 DRS 378 -1: 2017  
21                ©RSB 2017 - All rights reserved  
  
 
Annex N 
(normative)  
 
Advice to users  
The durability of a foam in a particular application and the comfort provided, depends on the use of the correct 
class of foam. The recommended class(es) of foam for each type of d uty are given in Table P.1. Foams of 
class numbers lower than the lowest of the applicable numbers shown in Column 3 are not suitable, but those 
of higher class numbers may be used if desired.  
Table R.1 — Classes of foam suitable for various types of duty  
1 2 3 
 
Type of duty   
Application examples  Class of foam 
recommended  
 
Light (L)  
 
 
 
Medium  
 
 
 
 
 
Heavy  
 
 
 
 
 
 
 
 
Very 
Heavy   
Padding; scatter cushions; pillows  
Light duty mattresses  
Light duty mattress toppers  
 
Backs and armrests for private and commercial 
vehicles  
Backs and armrests for domestic furniture  
Medium duty mattresses  
Medium duty mattress toppers  
 
Backs and armrests for cinema and theatre furniture  
Backs and armrests for contract furniture  
Backs and armrests for public transport  
Seats for private and commercial vehicles  
Seats for domestic furniture  
Heavy duty mattresses  
Heavy duty mattress toppers  
 
Seats for public transport  
Seats for cinema and theatre furniture  
Seats for contract furniture   
17; 20  
 
 
 
23; 26  
 
 
 
 
 
30 
 
 
 
 
 
 
 
 
36; 44; 48  
 
   
©RSB 2017 - All rights reserved                  22 
  
 DRS 378 -1: 2017  
23                ©RSB 2017 - All rights reserved  
 Bibliography  
 DRS 378-1: 2017  
ICS 97.140 
 
©RSB 2017  - All right s reserved