ICS 59.060.01  
 
Reference number
DRS 441 : 2020
© RSB 2020
  
 RWANDA 
STANDARD  DRS
441
First edition
2020 -mm-dd
Ear buds — Specification  
   
DRS 441 : 2020  
©RSB 2020 - 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  
 
 
 
 
 
 
 
 
© RSB2020  
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 reproduce thi s document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw  DRS 441 : 2020  
iii                ©RSB 2020 - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ...................... iv 
1 Scope  ................................ ................................ ................................ ................................ ................ 1 
2 Normative references  ................................ ................................ ................................ ....................... 1 
3 Terms and defi nitions  ................................ ................................ ................................ ...................... 1 
4 Requirements  ................................ ................................ ................................ ................................ ...2 
4.1 General requirements ................................ ................................ ................................ ....................... 2 
4.1.1  Cotton  ................................ ................................ ................................ ................................ ............... 2 
4.1.2  Spindles  ................................ ................................ ................................ ................................ ............ 2 
4.1.3  Finished ear bud  ................................ ................................ ................................ ............................... 2 
4.2 Specific requirements  ................................ ................................ ................................ ...................... 2 
5 Packing, labelling and disposal  ................................ ................................ ................................ .......3 
5.1 Packing  ................................ ................................ ................................ ................................ ............. 3 
5.2 Labelling  ................................ ................................ ................................ ................................ ........... 3 
Annex  A (normative)  Determination of submersion time and water absorption  ................................ .......5 
A.1 Principle  ................................ ................................ ................................ ................................ ............ 5 
A.2 Apparatus  ................................ ................................ ................................ ................................ ......... 5 
A.3 Procedure  ................................ ................................ ................................ ................................ ......... 5 
A.4 Calculation  ................................ ................................ ................................ ................................ ........ 6 
A.4.1  Submersion time  ................................ ................................ ................................ .............................. 6 
A.4.2  Water absorption  ................................ ................................ ................................ .............................. 6 
A.5 Report  ................................ ................................ ................................ ................................ ............... 6 
Annex  B (normative)  Determi nation of water soluble substances  ................................ ............................ 7 
B.1 Principle  ................................ ................................ ................................ ................................ ............ 7 
B.2 Apparatus  ................................ ................................ ................................ ................................ ......... 7 
B.3 Procedure  ................................ ................................ ................................ ................................ ......... 7 
B.4 Calculation  ................................ ................................ ................................ ................................ ........ 7 
B.5 Report  ................................ ................................ ................................ ................................ ............... 8 
Annex  C (normative) Determination of moisture regain  ................................ ................................ ............. 9 
C.1 Principle  ................................ ................................ ................................ ................................ ............ 9 
C.2 Apparatus  ................................ ................................ ................................ ................................ ......... 9 
C.3 Procedure  ................................ ................................ ................................ ................................ ......... 9 
C.4 Calculation  ................................ ................................ ................................ ................................ ........ 9 
C.5 Report  ................................ ................................ ................................ ................................ ............... 9 
Annex  D (normative)  Determination of the mass of the bud  ................................ ................................ .... 10 
D.1 Principle  ................................ ................................ ................................ ................................ ..........  10 
D.2 Apparatus  ................................ ................................ ................................ ................................ ....... 10 
D.3 Procedure  ................................ ................................ ................................ ................................ ....... 10 
D.4 Report  ................................ ................................ ................................ ................................ .............  10 
 DRS 441 : 2020  
©RSB 2020 - All rights reserved                  iv 
 Foreword  
Rwanda Standard sareprepared 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 441 was prepared jointly  by Technical Committee RSB/TC 029, Textile and Leather technology and 
RSB/TC 034, Medical eq uipment and accessories devices.  
In the prep aration of this standard, reference was made to the following standard  (s): 
KS2245:2010 Specification for cotton ear buds  
The assistance de rived from the above source is hereby acknowledged with thanks.  
Committee membership  
The following organizations were represented on the Technical Committee on Textile and leather technology 
(RSB/TC 029) in the preparation of this standard.  
Ministry of Trade and Industry (MINICOM)  
University of Rwanda -College of Science and Technology (UR -CST)  
Centre Hospitalier Universitaire de Butare (CHUB)  
Centre Hospitalier Universitaire de Kigali (CHUK)  
Rwanda Military Hospital Rwanda Military Hospital (RMH)  
 Rwanda Biomedical Centre  
Rwanda Inspectorate, Competition and Consumer Protection Authority ( RICA)  
OXALIS Ltd  
Rene Pharmacy  
UTEXRWA Ltd  DRS 441 : 2020  
v                ©RSB 2020 - All rights reserved  
 GLO CREATIONS  
LIXIL/SATO  
Rwanda Standards Board (RSB) – Secretariat  DRS 441: 2020  
1                ©RSB 2020 - All rights reserved  
 Ear buds — Specification  
1 Scope  
This Draft Rwanda Standard specifies requirements , sampling and test methods  for ear buds . 
2 Normative references  
The following documents are referred to in the text in such a way that some or all of  their content constitutes 
requirements of this document.  For dated references, only the editioncited applies. For undated references, 
the latest edition of the referenced document (including any amendments) applies.  
RS ISO 139 , Textiles — Standard atmosph eres for conditioning and testing  
RS181 , Solid waste — Handling, collection, transportation and disposal — Code of practice  
RS ISO 1833 -11, Textiles — Quantitative chemical analysis — Part 11: Mixtures of certain cellulose fibres 
with certain other fibres (method using sulfuric acid)  
RS EAS 96 -1, Sanitary towels — Specification — Part 1: Disposable  
RS ISO 3071, Textiles — Determination of pH of aqueous extract  
RS ISO 18416 , Cosmetics — Microbiology — Detection of Candida albicans  
RS ISO 21149, Cosmetics — Microbiology — Enumeration and detection of aerobic mesophilic bacteria  
RS ISO 21150 , Cosmetics — Microbiology — Detection of Escherichia coli  
RS ISO 22717 , Cosmetics — Microbiology — Detection of Pseudomonas aeruginosa  
RS ISO 22718 , Cosmetics — Microbiolo gy — Detection of Staphylococcus aureus  
3 Terms and definitions  
There are no terms and definitions in this standard.   
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 4 Requirements  
4.1 General requirements  
4.1.1  Cotton  
4.1.1 .1 Cotton fibres shall be well -carded and bleached to a good white,  free from chlorine, pieces 
ofthread, leaf, shell, fibre -dust and foreign matter. It may be slightly offwhite if it is sterilized.  
4.1.1.2  Cotton shall resist when pulled.  
4.1.2  Spindles  
Spindles of ear buds shall:  
a) bemade of  but not limited to  wood, rolled paper or extruded plastic.  
b) have a smooth surface,  bestraight and free from imperfections such as stress cracks or other molding 
defects.  
4.1.3  Finished  ear bud  
Finished ear buds  shall be free from loo se lint & adhesive and sharp edges, and the tips shall be tightly 
wrapped.  
4.2 Specific requir ements  
4.2.1  The ear buds shall comply with the  specific  requirements given in Table 1 when tested in accordance 
with the test methods specified therein.  
Table 1 — Specific requirements  of ear buds  
Parameter  Requirement  Test method  
Fibre composition, cotton  100%  RS ISO 1833 -11 
Dimensions ,mm  Stem  Length  72±1 Vernier caliper  
Diameter  2.0 ± 0.2  
Overall length, mm  75.0 ±1.0  
cotton  length , mm  15.0  ±2.0  
Diameter  5.0 ±0.3  
Absorbency for each gram of dry cotton, g, 
min 23 Annex A  
 
Submersion time, sec, max.  10 
Soluble Substances in cotton, %, max.   0.5 Annex B  
Moisture Regain, %, max.  8 Annex C DRS 441: 2020  
3                ©RSB 2020 - All rights reserved  
 Mass of bud on each end of a stem, g, min  0.03 Annex D 
Fluorescence   None  RS EAS 96 -1 
pH Value  6 to 8.  RS ISO 3071  
4.2.2  The ear bud  shall be produced under hygienic conditions and  comply with the microbiological 
requirements given in Table 2  when tested in accordance with the test methods specified therein.  
Table 2  — Microbiological  requirements  of ear buds  
Characteristic  Requirement  Test Method  
Total Viable Count,  CFU /g 100 RS EAS 96 -1 
Pseudomonas aeruginosa  Shall not be detected in 1g  of the 
sample  Staphylococcus aureus  
Candida albicans  
E.coli  
4.2.3 The spindles made from rolled paper or extruded plastic shall not break  when bent to approximately 
45º with fingers.  
5 Packing, labelling and disposal  
5.1 Packing  
The ear buds shall be packed in suitable containers which guarantee product safety and integrity  during 
storage and transportation.  
5.2 Labelling  
Each container shall be legibly and indelibly marked with the following information;  
a) Manufacturers  name, address and registered trade mark, if any;  
b) The name of the products as‘ ear bud’ on the container or box;  
c) The number of ear buds  in the a box and/or number boxes in a container  ; 
d) Instructions for use and  
e) Instructions for  disposal  in accordance withRS 181  
f) Lot/batch number;  
g) Fibre composition   
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 h) Date of manufacture and expiry; and  
i) Country of origin.  
 
 
 
 
 DRS 441: 2020  
5                ©RSB 2020 - All rights reserved  
 Annex  A 
(normative ) 
 
Determination of submersion time and water a bsorption  
A.1 Principle  
Cotton is placed in a metallic basket and allowed to sink in a tub of water. The time taken to submerge 
completely is noted and amount of water absorbed is measured.  
A.2 Apparatus  
A.2.1 Cylindrical basket, weighing 2.7 + 0.3 g, of height 80  mm, diameter 50 mm with square openings of 15 
mm to 20 mm, made of copper wire of 0.4 mm diameter.  
A.2.2 Tube of water, of 10 cm – 20 cm.  
A.2.3 Thermometer  
A.2.4 Stop watch, 0.2 seconds accuracy  
A.2.5 Container  
A.2.6 Weighing balance  
A.3 Procedure  
A.3.1 Take random specimen of 5 g of cotton wool from several stem s of ear buds in the laboratory sample.  
Place it loos ely in the cylindrical basket (A. 2.1) 
A.3.2 Weigh the ba sket using a weighing balance (A. 2.6) before placing the specimen. Weigh againafter 
placing the specimen.  
A.3.3 Drop the basket with its contents in a horizontal  position into a tub of water (A. 2.2), with water atabout 
20oC reaching a height of approximately 100 mm  
A.3.4 Measure by means of stop watch (A. 2.4), the time required for the basket to sink below thesurface of 
water in seconds  
A.3.5 Repeat the procedure above for two more specimens   
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 A.3.6 After testing the submersion time for each specimen, leave the submerged basket at the bottomof the 
water in A .3.4 for 3 minutes. Remove the basket with  its contents from water. Leave it for30 seconds in a 
horizontal position above the tub so as to drain the remaining water.  
A.3.7 Place the basket in a container (A. 2.5) of known weight (M1), weigh it M2).  
A.4 Calculation  
A.4.1  Submersion time  
Take the averag e of th e three measurements in A.3.4 and A. 3.5 as the sinking time in seconds.  
A.4.2  Water absorption  
Water absorbed = M 2 – (M1 + 2.7 + 5 ) 
 = M 2 - (M1 + 7.7 ) 
Where,  
M2 = mass of container + basket + cotton wool after absorption;  
M1 = mass of container  
 ܹater  absorbed  by each  gram  of cotton  wool =ݎ݁ݐܹܽ  ܾ݀݁ݎ݋ݏܾܽ
ݏݏܽܯ  ݂݋ ݊݋ݐݐ݋ܿ  ݈݋݋ݓ 
                                                                         = ெଶ – (ெଵ ା ଻.଻)
ହ 
A.5 Report  
A.5.1  Report the value calculated in A. 4.1 as the submersion time in seconds  
A 5.2  Report the value calculated A. 4.2 as the absorbency.  
  DRS 441: 2020  
7                ©RSB 2020 - All rights reserved  
 Annex  B 
(normative ) 
 
Determination of water soluble substances  
B.1 Principle  
Cotton wool is extracted in hot water and the extract is dried and then weighed.  
B.2 Apparatus  
B.2.1  Weighing balance  
B.2.2  Graduated flask  
B.2.3 Burner  
B.2.4  Funnel  
B.2.5  Filter paper  
B.2.6  Drier, with temperature control  
B.2.7  Clock  
B.3 Procedure  
B3.1 To 1 g of cotton from ear bud, add 100 mL of water and boil gently for 30 minutes, addingsufficient 
water t o maintain the original volume.  
B3.2  Pour the extract through a funnel into another vessel, transfer the cotton to the funnel and pressou t the 
water absorbed there -in. With a glass rod, wash the cotton with two 150 portions of hotwater, pressing the 
cotton  after each washing.  
B3.3  Filter the combined extracts and washings, evaporate to concentrate, transfer to the weighing  bottle and 
dry at 1050C to constant weight . Weigh the residual (M) in grams.  
B.4 Calculation  
 Soluble substances, % = 100 M  %  
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 B.5 Report  
Report  the value in B .4 as the percentage of water soluble substances.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DRS 441: 2020  
9                ©RSB 2020 - All rights reserved  
 Annex  C 
(normative ) 
Determination of moisture r egain  
C.1 Principle  
A known mass of absorbent cotton wool is dried and then the loss in mass expressed as a ratio of the  dry 
mass . 
C.2 Apparatus  
D.2.1  Weighing balance ; and  
D.2.2  Drier, with temperature control.  
C.3 Procedure  
D.3.1 Weigh M1, a known amount of cotton wool,  dry it at a temperature of 1000C to 1050C until constant 
mass is obtained.  
D.3.2 Weigh M2again. This is the dry mass.  
C.4 Calculation  
Moisture regain = (୑ଵି୑ଶ)
୑ଶx100  
C.5 Report  
Report the value calculated in D .4 as the moisture regain in per cent.   
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 Annex  D 
(normative ) 
 
Determination of the mass of the bud  
 
D.1 Principle  
Mass of a bud taken from one end of a stem is measured on a weighing bal ance.  
D.2 Apparatus  
Weigh ing balance, accuracy 0.001g.  
D.3 Procedure  
E.3.1 Conditioning  
Condition the specimen in accordance with RS ISO 139 . 
E.3.2 Take the mass of the conditioned bud  with a weighing balance E .2. 
Take mass measurementof four other buds. Calculate  the average mass of bud from the five measurements.  
D.4 Report  
Report the average mass of the bud in E3.2 as the mass of bud.  
 
 
 
 
 
 DRS 441: 2020  
 
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