ICS 65.060.01  
 
Reference number  
DRS  268-3: 2020  
© RSB 2020  
  
 RWANDA 
STANDARD  DRS  
268-3  
 
2nd edition  
2020 -June  
 
Agroprocessing  machines — Specification 
—  
Part 3:  
Rice mill  
   
DRS  268-3: 2020  
©RSB 2020  - All rights reserved    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 2020  
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 this 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    
©RSB 2020  - All rights reserved   Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ..........................  3iv 
1 Scope  ................................ ................................ ................................ ................................ ...................  51 
2 Normative references  ................................ ................................ ................................ .........................  51 
3 Terms and definitions  ................................ ................................ ................................ ........................  51 
4 Classification  ................................ ................................ ................................ ................................ ....... 62 
5 Material of construction  ................................ ................................ ................................ .....................  73 
6 Performance and safety requirements  ................................ ................................ .............................  73 
7 Workmanship and finish  ................................ ................................ ................................ ....................  84 
8 Maintenance and operation  ................................ ................................ ................................ ...............  84 
9 Sampling and testing  ................................ ................................ ................................ .........................  84 
10 Marking  ................................ ................................ ................................ ................................ ................  84 
 DRS  268-3: 2020  
©RSB 2020  - 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 
adop ted by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS  268-3 was prepared by Technical Committee RSB/TC 047, Steel aluminium and related products . 
In the preparation of this standard, reference was made to the following standard  (s): 
1) XYZ: Title  
2) XYZ:  Title 
The assistance de rived from the above source is hereby acknowledged with thanks.  
This second  edition cancels and replaces the first  edition (RS  268-3: 2015 ) which  has been technically 
revised.  
DRS  268 consists of the following parts, under the general title Agroprocessing machinery — Specification : 
 Part 1: Rice thresher  
 Part 2: Power operated maize sheller  
Part 4: Heated air mechanical grain dryer  
Part 5: Maize mill  
Committee membership  
The following organizations were represented on the Technical Committee on Title of TC  (RSB/TC nnn) in the 
preparation of this standard.  
University of Rwanda/college of science and technology  
University of Rwanda/College of agriculture animal science and veterinary medicine  
Kabizu business group  
Rwanda Polytechnic/IPRC Kigali   
©RSB 2020  - All rights reserved   Rwanda Polytechnic/IPRC Ngoma  
Rwanda Polytechnic/IPRC Musanze  
RWANTECH Boilers  
Rwanda Inspectorate and competition aut hority  
Rwanda Institute for Conservation Agriculture  
ACER Ltd  
Rwanda  Standards Board  (RSB) – Secretariat  
  DRS  268-3: 2020  
©RSB 2020  - All rights reserved     
Agroprocessing machines — Specification — Part 3: Rice mill  
1 Scope   
This Draft Rwanda Standard specifies the classification, requirements, sampling and methods of test for rice 
mill. 
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 edition cited applies. Fo r undated references, 
the latest edition of the referenced document (including any amendments) applies.  
DRS  269-3, Agroprocessing machines  — Test methods — Part 3: Rice mill    
DRS RS  241, Agriculture machine ry — Methods of sampling   
RS 236, Acoustics — Noise pollution — Tolerance limit  
RS 340, Food processing machines — Specifications  
 
3 Terms and definitions   
For the purposes of this standard, the follow ing terms and definitions apply  
3.1  
bran  
outer layer of the brown rice consisting of the aleurone  cells covering the endosperm of the rice grain  
3.2  
broken grains  
grains that broken in the process of milling which have a size of less than eight -tenth (8/10) of the average 
length of whole grain  
3.3  
coefficient of hulling  
measure of the ability of  the machine to remove the hulls   
©RSB 2020  - All rights reserved   3.4  
coefficient of wholeness  
measure of the ability of the machine to remove the hulls without breaking the grain  
3.5  
head rice  
grain or fraction of grain with its length equal to or greater than eight per tenth (8/10)  of the average length of 
the whole grain  
3.6  
hulling efficiency  
product of the coefficient of hulling and the coefficient of wholeness of grains, expressed in percent  
3.7  
input capacity  
weight of palay per unit loading time into the hopper/intake pi t, expressed in kilogram per hour  
3.8  
milling degree  
extent or degree by which the bran layer of the brown rice is removed as a result of whitening  
3.9  
percent head rice  
ratio of the weight of grains that do not break in the process of milling and with a size of three -fourth (3/4) or 
more of the whole grain to the total weight of milled rice, expressed in percent  
3.10  
percent head rice index  
ratio of the percent head rice ob tained in actual testing, to the percent head rice obtained from the laboratory 
test mill.  
4 Classification  
A paragraph.  
The rice mill shall be classified based on the following:  
a) method of operation; and   DRS  268-3: 2020  
©RSB 2020  - All rights reserved    1. single -pass rice mill; and   
2. multi -pass rice mil l  
b) type of huller  
1. under -runner stone disc; and   
2. rubber roll type  
 
5 Material and construction  
5.1 Food zone area shall be made from food grade materials.  
5.2 Non-food zone area may be made from carbon steel that has been rendered corrosion resistant  
5.3 Construction of rice threshing machine shall be done in accordance with RS 340.  
6 Performance and safety requirements  
6.1 The performance criteria for rice mill shall be as specified in Table 1  
Table 1 — Performance criteria for rice mill  
criteria  Performance  
Single Pass  Multi Pass  
Cono  Rubber roll  Cono  Rubber roll  
Milling Recovery 
Index, min.  0.97 0.98 0.97 0.98 
Percent Head Rice 
Index, min.  0.90 0.90 0.90 0.90 
Hulling Efficiency 
percent, min.  80 80 80 80 
Milling Degree  Well milled  
 
6.2 The specified capacity at the brown rice output of the paddy separator shall be attained, with maximum of 
10 pieces of palay per kilogram of brown rice output.  
6.3 Lubrification shall be provided for non -sealed type bearings and belt tightening.  
6.4 Provisions for safety of the operator from all moving components of the rice mill such as belt guard or 
cover shall be included.   
©RSB 2020  - All rights reserved   6.5 6.2  The maximum level for Noise Level, [db] (A) for threshing machine shall be as specified in RS 236.  
7 Workmanship and fini sh 
7.1 Rice mill shall be free from manufacturing defects that may be detrimental to its operation.  
7.2 Any uncoated metallic surfaces shall be free from rust and shall be painted properly with food grad paint 
for metallic in contact with rice.  
7.3 Rice mill shall be free from sharp edges and surfaces that may injure the operator.  
7.4 Rice mill shall be  constructed to  ease to operation and cleaning  
8 Maintenance and operation  
8.1 Each rice mill shall be provided with a set of relevant mechanic tool kit.  
8.2 An instruction manual (User’s manual, parts catalogue and service manual) shall be provided.  
8.3 All components that require regular maintenance, servicing and adjustment should be easily accessible.  
9 Sampling and testing  
9.1 The rice mill shall be s ampled for testing in accordance with RS 241.  
9.2 The sampled rice mill shall be tested in accordance with RS 269 -3.  
10 Marking   
Rice mill shall be indelibly and legibly marked with the following information in one of three official languages 
used in Rwand a:   
a) Name and registered trademark of the manufacturer;  
b) brand;  
c) model;  
d) serial number;  
e) country of manufacture;  
f) input capacity, kg/h;  
g) rating power, kW;  DRS  268-3: 2020  
©RSB 2020  - All rights reserved    h) production capacity  DRS  268-3: 2020  
 
Price based on nnn  pages  
©RSB 2020 - All rights reserved