ICS 71.100.80  
 
Reference number  
DRS 277: 2021  
  © RSB 2021  
  
 RWANDA 
STANDARD  DRS  
277:2021  
  
 
Second  edition  
2021 -mm-dd 
 Water quality  — Chemicals used for 
treatment of water intended for human 
consumption   
Part 6: Hydrated lime  
   
DRS 277: 2021  
©RSB 2021 - 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 2021  
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 RSB.  
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   DRS 277: 2021  
iii                ©RSB 2021 - All rights reserved  
 Contents  Page 
1 Scope  ................................ ................................ ................................ ................................ .............  1 
2 Normative references  ................................ ................................ ................................ ...................  1 
3 Terms and definitions  ................................ ................................ ................................ ..................  1 
4 Chemical  requirements  ................................ ................................ ................................ ................  2 
5 Physical requirements  ................................ ................................ ................................ .................  4 
6 Packaging and marking  ................................ ................................ ................................ ...............  4 
6.1 Packaging  ................................ ................................ ................................ ................................ ...... 4 
6.2 Marking  ................................ ................................ ................................ ................................ ..........  4 
7 Sampling  ................................ ................................ ................................ ................................ ....... 5 
Annex  A (normative)  Sampling and specification of tests  ................................ ................................ ... 6 
A.1 General sampling procedure  ................................ ................................ ................................ ....... 6 
A.2 Sampling of hydrated lime delivered in bulk  ................................ ................................ .............  6 
A.3 Sampling of hydrated lime delivered in containers  ................................ ................................ .. 6 
A.4 Mixing the composite sample  ................................ ................................ ................................ ..... 6 
A.5 Compliance with specification  ................................ ................................ ................................ .... 6 
 DRS 277: 2021  
©RSB 2021 - All rights reserved                  iv 
 Foreword  
Rwanda Standards are prepared by Technical Committees and approved by Rwanda 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 Standards adopted 
by Technical committees are ratified by members of RSB  Board of Directors for publication and gazettment as 
Rwanda Standards.  
RS 2 77 was prepared by Technical Committee RSB/TC 013, Water and Sanitation . 
This second edition cancels and replaces the first edition RS 2 77: 201 5 which has been technically revised.  
  DRS 277: 2021  
v                ©RSB 2021 - All rights reserved  
 Committee membership  
The following organizations were represented on the Technical Committee on Water and Sanitation (RSB/TC 
013) in the preparation of this standard.  
Enviroserve Rwanda  
Ministry of Trade and Industry (MINICOM)  
Ministry of Environment (M oE) 
Ruliba Clays  
Rwanda Environmental Management Authority (REMA)  
Rwanda Mines, Petroleum and Gas Board (RMB)  
Rwanda Polytechnic (RP)  
Rwanda Utility Regulatory Authority (RURA)  
Shine Engineers Multisectoral Company Ltd (SEMC)  
Star Construction and Consultancy (SCC)  
Standards for Sustainability (SFS)  
SULFO Rwanda  
University of Rwanda - College of Science and Technology (UR -CST)  
Water and Sanitation Corporation (WASAC)  
Rwanda Standards Board (RSB) – Secretariat  
 DRS 277: 2021  
1                ©RSB 2021 - All rights reserved  
 Water quality — Chemicals used for treatment of water intended 
for human consumption  — Part 6: Hydrated lime specifications  
1 Scope  
This Committee Draft Standard lays down requirements and methods of test for hydrated lime used for treatment 
of water intended for human consumption   
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 17378 -2 water quality — determination of arsenic and antimony — part 2: method using hydride generation 
atomic absorption spectrometry (hg -aas) 
ISO 21587 -1, Chemical analysis of aluminosilicate refractory products (alternative to the X -ray fluorescence 
method) — Part 1: Apparatus, reagents, dissolution and gravimetric silica  
ISO 21587 -2, Chemical analysis of aluminosilicate refractory products (alternative to the X -ray fluorescence 
method) — Part 2: Wet chemical analysis  
ASTM C25 – 19 Standard Test Methods for Chemical Analysis of Limestone, Quicklime, and Hydrated Lime  
ASTM E449 – 18 Standard Test Methods for  Analysis of Calcium Chloride  
ISO 3165, Sampling of chemical products for industrial use — Safety in sampling   
ISO 8213, Chemical products for industrial use — Sampling techniques — solid chemical products in the form 
of particles varying from powders to c oarse lumps  
3 Terms and definitions  
For the purposes of this standard, the following terms and definitions apply  
3.1  
available lime  
oxides of calcium and magnesium which enter into a desired reaction under the conditions of a specific method 
or process   
©RSB 2021 - All rights reserved                  2 
 3.2  
hydrated lime   
very finely divided powder resulting from the hydration of quicklime, consisting essentially of calcium hydroxide, 
Ca(OH) 2. Hydrated lime used to be slaked lime too   
3.3  
lot  
quality of hydrated lime that bears the same batch identification, from one manufacturer, submitted at any one 
time for inspection and testing   
3.4  
quicklime   
calcium oxide CaO , the result of burning limestone   
3.5  
limestone   
calcium carbonate, CaCO 3, sometimes called agricultural lime   
3.6  
w/v  
weight per volume   
3.7  
manufacturer   
party and manufacturers, fabricates, or produces materials or products   
4 Chemical requirements  
4.1 When tested, the hydrated lime shall comply with all the appropriate requirements given in the Table 1 : 
  DRS 277: 2021  
3                ©RSB 2021 - All rights reserved  
 Table 1 — Chemical Requirements  
S/N  
Constituents   
Hydrated  lime 
 Test method  
Grade 
A Grade 
B Grade 
C 
i.  Available lime (calculated as 
calcium oxide percent, min  95.0 95.0 95.0 ISO 21587  
(part 1&2)  
ii.  Available lime (calculated as 
calcium hydroxide), percent, min  92 87 83 ASTM E449 - 
18 
iii.  Magnesium oxide, percent, max.  0.6 0.6 0.6 ISO 21587  
4.2 Impurities  
The product  shall conform to the requirements specified in Table 2  
Table 2  — impurities  
S/N  
Constituents  Limit in mass fraction in % of dry 
product  Test method  
Grad A  Grad B  Grad C  
i.  Carbon dioxide, percent, max  3.0 4.0 5.0 ASTM C25 - 19 
ii.  Si expressed as SiO 2 max.  2.5 3.0 4.0 
ISO 21587 (part 1&2)  
ASTM C25 - 19 iii.  Al expressed as Al 2O3 max 0,5 1,0 2,0 
iv.  Fe expressed as Fe 2O3 max 0,5 1,0 1,5 
v.  Mn expressed as MnO 2 max.  
 0,2 0,4 0,5 
vi.  CaCO 3 max.  7,0 8,0 9,0 ASTM C25 - 19 
vii.  Water insoluble matter, max  2 2 2 ASTM C25 - 19 
4.3  Hydrated lime  for water treatment shall not contain inorganic contaminants in excess of limits indicated 
in Table 3.  
Table 3 — limits of inorganic contaminants in hydrated lime for water treatment  
S/N Substance  Limit, mg/L, max.   Test methods  
i Arsenic as As,  0.01  ISO 17378 -2 
ii Lead as Pb,  0.01  ISO 8288  
iii Mercury as Hg,  0.001  ISO 12846   
©RSB 2021 - All rights reserved                  4 
 iv Nitrite as NO 2- 0.1  ISO 6777  
v Cadmium as DRS ,  0.003  ISO 5961  
vi Chromium as total Cr,  0.005   ISO 9174  
vii Copper as Cu++ 1  ISO 8288  
viii Cyanide as CN - 0.07  ISO 6703  
ix Anionic surfactant (reacting with methylene blue)  Absent  ISO 7875  
x Barium as Ba ++ 0.7 ISO 11885  
5 Physical requirements  
5.1 The hydrated lime shall be free from fuel ashes and under burnt particles.  
5.2 The hydrated  lime shall be a fine white powder which shall pass through a 425 micro sieve.  
5.3 The Table 4 gives some physical characteristics for hydrated lime  
Table 4 — Some physical properties of hydrated lime  
Property  Hydrated lime  
Specific gravity  2.1 – 2.4  
Bulk density  300 – 600 kg/m3  
Solubility in water   1,85 g/l at 0 °C  
1,65 g/l at 20 °C  
1,53 g/l at 30 °C  
Melting point  Decomposes at 580 °C and forms calcium oxide and water  
Particle distribution  should be uniform  
Particle size  Product shall be free from lumps or foreign material that might interfere with the operation of dry 
feed, pneumatic or hydraulic equipment  
6 Packaging and marking  
6.1 Packaging  
Hydrated lime shall be packaged in air -tight or moisture -proof containers.  
6.2 Marking  
6.2.1  The container or the attached label shall be legibly and indelibly marked with the following information:  DRS 277: 2021  
5                ©RSB 2021 - All rights reserved  
 a) name or trade name and physical addresses o f the manufacturer  
b) name “hydrated lime for water treatment”;  
c) grade of the hydrated lime;  
d) lot number;  
e) net weight of contents when packed; and  
f) statemen t of conformity to the standard  
6.2.2  The supplier shall provide a certificate of analysis against the standard  
NOTE  The user should verify the relevance of that certificate  
7 Sampling  
Additionally, to the sampling provisions in annex A; Observe the general recommendations of ISO 3165 and 
prepare the laboratory sample(s) required by the relevant procedure described in ISO 8213.   
©RSB 2021 - All rights reserved                  6 
 Annex  A 
(normative)  
 
Sampling and specification of tests  
A.1 General s ampling procedure  
Sampling shall be done expeditiously as possible in order to avoid undue exposure of the material to the air. 
Sample shall not be taken from broken packages. The breaking down and canning and quartering or bulk 
samples shall be carried o ut under cover. The samples so drawn shall be deemed to represent the lot.  
A.2 Sampling of hydrated lime delivered in bulk  
The hydrated lime supplied in bulk, take approximately equal portions from at least 20 different positions in order 
to form a composite  sample of at least 12 kg. The portion shall be taken in such a manner that the composite 
sample represents an average of all parts of the lot, and shall not contain a disproportionate share of the top or 
bottom layers. Proceed in accordance with clause A. 4.  
A.3 Sampling of hydrated lime delivered in containers  
For hydrated lime delivered in containers, if the lot consists of twelve or less containers, sample each container. 
If a lot consists of more than twelve containers at random from the lot. Take approxi mately equal representative 
quantities of not less than 1 kg with clause A.4.  
A.4 Mixing the composite sample  
Mix the composite sample thoroughly on a clean, dry, hard surface and spread it out flat and scoop the mass 
together into a cone. Flatten the cone a nd divide into four equal parts. Remove the two diagonally opposite 
parts. Mix the two remaining parts together and from a cone out of it again. Repeat the operation of mixing, 
conning and quartering until finally about 3 kg of the average sample represent ative of the lot is left. Divide into 
three approximately equal representative portions, immediately place each portion in an airtight container of 
such size that it is nearly filled by the sample and mark with full details including the date of sampling. Submit 
one sample to the laboratory for test, one sample to the manufacturer and keep the third sample for reference.  
A.5 Compliance with specification  
The test samples prepared for each lit shall be subjected to various physical and chemical tests. The lot shall 
be declared complying with this specification only if the prescribed tests  conform to the requirements of this 
standards . 
  DRS 277: 2021  
7                ©RSB 2021 - All rights reserved  
 Bibliography  
[1] ASTM C50: 2013, Standard Practice for Sampling, Sample Preparation, Packaging, and Marking of Lime 
and Limestone Products  
[2] ASTM D1129: 2013 Terminology related to water  
[3] BS EN 12485: 2010, Chemicals used for treatment of water intended for human consumptio n — Calcium 
carbonate, high -calcium lime, half -burnt dolomite, magnesium oxide and calcium magnesium carbonate 
— Test methods  
[4] IS 1514 (1990): Methods of sampling and test for quick lime and hydrated lime [CHD 1: Inorganic 
Chemicals]  
[5] ANSI/AWWA Standard fo r Quicklime and Hydrated Lime. ANSI/AWWA B202 -93, AWWA, 1993.  
[6] ISO 3696, Water for analytical laboratory use — Specification and test methods  
[7] Guidance Note for Completion of a Material Safety Data Sheet. National Occupational Health and 
Wellington, 1996  
[8] Standard Methods for the Examination of Water and Wastewater. 19th Ed., APHA, AWWA, WEF. 1995.  
 DRS 277: 2021  
 
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