DRAFT KE NYA STANDAR D   DKS  2912 : 2020 
ICS 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Solid biofuel —Sustainable  Charcoal and 
carbonized briquettes for household and 
commercial use — Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
©KEBS 20 20          First Edition 20 20 
 
 
 
 
 DKS 2912 : 2020 
             © KEBS 2020  — All rights reserved  ii  
 
 
 
TECHNICAL COMMITTEE REPRESENTATION  
 
The following organi zatio ns were represented on the Technical Committee:  
Kenya Forest ry Research Institute (KEFRI)  
Clean Cooking Association of Kenya (CCAK)  
Fine Aroma (FA)  
University of Nair obi 
Kenya Industrial Research and Development Institute  (KIRDI ) 
Eco-charcoal Ltd 
Sanivation 
Kenya Revenue A uthority  
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ)  
Stockholm Environment Institute (SEI) . 
Kenya Bureau of Standard - Secretariat . 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
REVISION OF KENYA STANDARDS  
 
In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed. Suggestions for 
improvements to published standards, addressed to the Managing Director, Kenya Burea u of Standards, are 
welcome.  
 
 
 
 
 
© Kenya Bureau of Standards, 20 18 
 
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 12 of 2001  of the Laws of Kenya, copyright subsists 
in all Kenya Standards and except as provid ed un der Section 26 of this Act, no Kenya Standard produced by Kenya Bureau of Standards 
may be reproduced, stored in a retrieval system in any form or tra nsmitted by any means without prior permission in writing from the 
Managing Director . 
 
 
 
 
 DRAFT KENYA STANDARD      DKS 2912 : 2020 
ICS23.040.20  
© KEBS 2017 — All rights reserved           iii 
  
 
 
 
 
 
 
 
 
 
 
Solid biofuel — Sustainable   Charcoal and 
carbonized briquettes for household and 
commercial use — Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
KENYA BUREAU OF STANDARDS (KEBS)  
 
Head Office:  P.O. Box 54974, Nairobi -00200, Tel.: (+ 254 020 ) 605490, 60 2350,  Fax: (+254 020 ) 604031  
E-Mail: info@kebs.org, Web:http://www.kebs.org  
 
Coast Region     LakeRegion     Rift Valley Region  
P.O. Box 99376, Mombasa -80100   P.O. Box 2949, Kisumu -40100        P.O. Box 2138, Nakuru -20100  
Tel.: (+254  041) 229563, 230939/40  Tel.: (+254 057) 23549, 22396        Tel.: (+254 051) 210553, 210555  
Fax: (+254  041) 229448    Fax: (+254 057) 21814    
 
 
 
 
 DKS 2912 : 2020 
             © KEBS 2020  — All rights reserved  iv  
 
 
 
Foreword  
 
This Kenya Standard was prepared by the Appropriate T echnical Committee under the guidance of the 
Standards Project s Committee , and it is in accordance with the procedures of the Kenya Bureau  of Standards . 
 
The use of wood residues for charcoal provides an effective means of improving the utilization of timber. Wood 
charcoal can be produced by a wide variety of methods, ranging fr om si mple earth - covered kilns to the beehive 
kiln and modern retorts for continuous carbonization.  
 
With the increase  in the use of  sustainable  charcoal for household purposes, the need has arisen for an  updated 
specification that establishes a standard f or co mparison and testing.  
 
Because of the possibility of its being unsuitably stored or transported, charcoal marked in accordance with 
clause 6  of this standard cannot be assumed to comply with all the relevant requirements at any time other than 
the tim e of dispatch from the factory where it was produced.  
 
During the preparation of this standard, reference was made to  the following document:  
 
SANS 1399:2008 , South African Standard, Wood charcoal and carbonized briquettes  for household use   
 
 
Acknowledg ement  is hereby made for  the assistance derived from thi s source .DRAFT KENYA STANDARD      DKS 2912 : 2020 
© KEBS 2017 — All rights reserved         1  
 
Solid biofuel — sustainable Charcoal and carbonized briquettes  for 
household and commercial use — Specification  
 
1 Scope   
 
This standard specifies requirements for sustainably produced  charc oal and carbonized briquettes  that are 
derived  from forest, plantation,  sustainably harvested  wood and other forest products, by –products and 
residues from wood processing industry, chemically untreated wood,  herbaceous biomass, fruit biomass, 
aquatic  biom ass, agro-industrial residues  (e.g. sugarcane bagasse , rice husks  etc.), treated faecal sludge and 
organic market wastes , in lump and briquette form that is intended for household and commercial use.  
 
2  Normative reference  
 
The following standard con tains  provisions,  which, through reference in this text, constitute  provisions of this 
standard. All standards are subject to revision and, since any reference to a standard is deemed to be a 
reference to the latest edition of tha t standard, parties to agr eemen ts based on this standard are encouraged 
to ensure the use of the most recent edition of the standard indicated below.  
 
ISO 3310 -2, Test sieves – Technical requirements and testing – Part 2: Test sieves of perforated metal pl ate.                                                                                                                         
 
3  Terms and Definitions  
 
For the purposes of this standard, the following terms and definitions apply:  
 
3.1 Acceptable  
In compliance with the provision of this standard, acceptable  to the authority administering this standard, or 
to the parties concluding the purchase  contract as relevant.  
 
3.2 Ash content  
The residue when charcoal or carbonized briquette s are incinerated i n air under standardized conditions . 
 
3.3 Binder  
An organic material that, when added to biochar (see 3.3.1) and  compacted, holds  the granules together in a 
solid mass  (such as but not limited to starch, gum arabic , molasses , vegetable oil, lignin)  
  
3.3.1 Bio char  
Carbonised organic material  
 
3.4 Charcoal  
Lump c arbonaceous residue material from incomplete combustion or pyrolysis of organic materials   
 
3.5 Sustainable  charcoal  
charcoal produced from sustainable feedstock with efficient carbon ization technology  
 
3.6 Sustainable feedstock  
Natural resources that are established  and managed to  ensure long-term provision of raw materials with no 
negative impact to the environment and the people.  
 
3.7 Efficient  carboni zatio n technology  
Efficient carbonization  is a process  by which solid materials with  increasing content of the element carbon 
are formed from organic material usually by pyrolysis in proficient  technology  that do not harm the 
environment and minimize mat erial and energy losses . 
 
 
3.8 Carbonized briquette  
A briquette produced by compressing, compacting, densification and rolling biochar w ith a suitable binder . 
 
3.9 Fixed carbon content  DKS 2912 : 2020 
 
             © KEBS 20XX — All rights reserved  2 The carbon content that remains after the removal of the ash content  and volatile matter content from dry 
charcoal  or carbonised briquettes  under standardised conditions . 
 
3.10 Moisture content  
The water contained by charcoal or carbonized briquette s and that will be removed by heating at  
105 °C  
 
3.11 Untreated  wood  
Wood tha t has, since felling, not been in contact with a pesticide or a wood preservative  
 
 
3.12 Volatile matter content  
The gasses  other than water vapours  lost when  charcoal or carbonized briquette  are heated  under 
standardized condi tions  (see 5.8)  
 
 
 
 
3.13 
Foreign  matter  
Any material other than the prescribed ingredients of the sustainable charcoal and carbonized briquettes that  
compromises the product integrity e.g. sand, sticks , paper  stones  etc. 
 
3.14 
Additives  
Acceptable materials used to aid production, delivery or combustion (e.g. pressing aids, staging inhibitors or 
any other additives like starch, gum Arabic, molasses, vegetable oil, and lignin ). 
 
3.15 
Defective  
Sustainable  charcoal or carbonized briquettes  that fail, i n one  or more respects, to comply with the relevant 
requirements of this standard  
 
3.16 
Calorific Value 
Energy contained in a fuel d eterm ined by the heat energy released by the complete combustion of specified 
quantity fuel material expressed in MJ/Kg.  
 
3.17 
Density  
Mass per unit volume (Kg/m3) 
 
 
 
 
4  Requirements  
 
4.1 Type of raw material  
 
The biomass material used to produ ce sustainable charcoal and carbonized briquettes  shall be such as to be 
acceptable . 
 
4.2 Foreign matter  and additives  
 
4.2.1 Sustainable  charcoal and c arbonized briquette  shall be free from foreign matter.  
 
4.2.1 Additives materi als shall be such as to be acceptable . 
 
4.2.3 A binder  used  shall be such as to be acceptabl e. 
 
 DKS 2912 : 2020 
 
© KEBS 20XX — All rights reserved      v       3 
  
4.3 Physical requirements  
 
4.4 General  
 
The organic material used to  produce sustainable charcoal  or carbonised briquette s shall be such as to be 
acceptable . 
 
4.4.1  General  
 
The shape and size of sustainable charcoal or  carbonised briquettes shall be such as to be acceptable.  
 
4.4.2  Sieve analysis  
 
4.4.2. 1Charcoal  
  
When lump sustainable charcoal are tested in accordance with 5. 2, not more that 5 % (by mass ) sha ll be 
retained on a test sieve of aperture size 106 mm, and the quan tity that passes through a test sieve of aperture 
size 15.0 mm shall not exceed 5 % (by mass).  
 
4.4.2.2 Carbonized briquettes  
 
When carbonized briquettes  are tested in accordance with  5.3, the amount that passes through a test sieve 
of aperture size 15.0 mm shall not exceed 2. 5 % (by mass).  
 
4.4.3   Resistance  to dropping  
 
4.3.3. 1When an unopened container of carbonized briquettes is tested in accordance  with 5.4, the proportion 
of the  contents that passes through a test sieve of aperture size  9.5 mm  shall not exceed 5 % (by mass).  
 
4.3.3.2  When an unopened container of sustainable charcoal is tested in accordance with 5.4, the proportion 
of the contents that passes through a test sie ve of  aperture size 9.5 mm shall not exceed 7.5 % (by mass).  
 
 
4.5  Chemical  requirements  
 
4.5.1  Moisture  content  
 
When determined in accordance with 5.6, the moisture content of sustainable  charcoal and carbonized 
briquettes  shall not  exceed 10 %.  
 
4.5.2  Volat ile matter content  
 
When determined in accordance with 5.8, the volatile matter content shall not  exceed 2 05 % in the case of 
sustainable charcoal , and in the case of carbonized briquettes  shall not exceed 25%  
 
4.5.3  Ash content  
 
When determined in accordance with 5.9, the ash content of sustainable  charcoal shall not exceed 5 % in 
the case of charcoal , and in the case of carbonized briquettes  shall not exceed 27 % 
 
4.5.4  Fixed  carbon content  
 
When determined in accordance with 5.10, the fixed carbon content of sustainable  charcoal shall not be less 
than 75 % in the case of charcoal , and 44% in the case of carbonized briquettes .                                                                                               
 
5  Inspection and methods of test  
 
5.1  Inspection  
 DKS 2912 : 2020 
 
             © KEBS 20XX — All rights reserved  4 Visually inspect each container in the sample drawn in accordance with A.2.2.1 (see Annex A ) for 
compliance  with those requi rement s of the standard for which tests to assess compliance are not given in 5.2 
to 5.10 (inclusive).  
 
5.2  Sieve analysis for sustainable  charcoal  
 
5.2.1  Apparatus  
 
5.2.1.1  Two balances, of suitable capacity, that have scale divisions at intervals not e xceedi ng 1 g and 20 g,  
respectively.  
 
5.2.1.2  Two round test sieves, that comply with the requirements of KS ISO 3310 -2, each  equipped with a 
cover and a receiver, and that ha ve square apertures of nominal size 106 mm and9,5 mm, respectively.                                                                                                                                
 
5.2.2 Test  specimens  
 
Take, at random, two containers from t he sample under test (see A.2.2.2 of Annex A ). 
 
 
5.2.3 Procedure  
 
Determine t he mas s of the contents of one container to the nearest 20 g. Using a horizontal to and fro 
movement, sieve the contents of the container on the 106 mm test sieve (see 5.2.1.2) in  such increments as 
to ensure that, on completion of the sieving of each incr ement,  each piece in the increment has been in direct 
contact with the sieve plate. Then turn each piece of sustainable charcoal  retained on the sieve to determine 
whether it pass es, in any position (without applying  force), through the sieve. Before the n ext in crement is 
sieved, remove all the pieces retained on the sieve and keep them for the determination of their mass.  
 
Using the 9,5 mm test sieve, sieve, as above, the charcoal  that passed through the 106 mm test sieve, but 
do not turn each piece retain ed on the sieve. Retain the charcoal that passed through the 9,5 mm test sieve. 
Determine the mass of this quantity and t he pieces retained on the 106 mm test sieve separately to the 
nearest 1 g.  
 
Repeat the test on the  second container.  After completion,  retain all the fractions from each  container (see 
5.6.3 and 5.7).  
 
5.2.4 Expression  of results  
 
5.2.4.1 For  each contai ner calculate, to the nearest 0. 1 %, the retention on the 106 mm test sieve, as follows:  
 
 
𝑀1
𝑀2𝑥100 
 
 
Where; 
 
m1 = mass of the pie ces re tained on the 106 mm test sieve, in grams; and  
 
m2 = mass of the total contents of the container before sieving, in grams.  
 
Record the mean of the two results.  
 
5.2.4.2   For each contai ner calculate, to the nearest 0. 1 %, the quantity that passed t hrough  the 
9.5 mm test sieve, as follows:  
 
𝑀3
𝑀2𝑥100 
 
 
 DKS 2912 : 2020 
 
© KEBS 20XX — All rights reserved      v       5 
 Where; 
 
m2    is the mass of the total contents of the container before sieving, in grams; and  
 
m3    is the mass of the quantity that passed through the 9,5 mm test sieve, in grams.  
 
Record the mean of the two results.  
 
5.2.4.3 Check  for compliance with 4 .4.2. 
 
5.3 Sieve  analysis for carbonized briquettes  
 
5.3.1 Apparatus  
 
5.3.1.1 Balances , as in 5.2.1.1.  
 
5.3.1.2 Round  test sieve, that complies with the requirements of KS ISO 3310 -2, that is equipped with a 
cover and a receiver, and that has square apertures of nominal size 9,5 mm. 
 
5.3.2 Test  specimens  
 
Take, at random, two containers from the sample under test (see A.2.2.2 of Annex A ). 
 
 
5.3.3 Procedure  
 
Determine the mass of the contents of one container to the nearest 20 g. Separate al l the unbroken briquettes 
from the broken briquettes and fines. Using a horizontal to and fro movement, sieve the broken briquettes and 
fines on the test sieve in such incr ements as to ensure that, on the  completion of the sieving of each increment, 
each p iece in the increment has been in direct contact with the sieve plate. Determine the mass of the quantity 
that passed through the test sieve to the nearest 1 g.  
 
Repeat the  test on the second container. Retain all the unbroken briquettes from each containe r 
(see 5.6.3 and 5.7).  
 
5.3.4 Expression  of results  
 
5.3.4.1 For  each contai ner calculate, to the nearest 0. 1 %, the quantity that passed through the test sieve, as 
follows : 
 
𝑀4
𝑀5𝑥100 
 
Where; 
 
m4    is the mass of the quantity that p assed through the  15.0 mm test sieve, in grams; and  
 
m5    is the mass of the total contents of the container, in grams.  
 
Record the mean of the two results.  
 
5.3.4.2 Check  for compliance with 4.4.2.  
 
 
5.4  Drop resistance of container content  
 
5.4.1 Apparatus  
 
5.4.1.1   Dropping device, comprising a divided table (or single -leaf device), fitted with a release mechanism, 
that is so spring -operated as to produce, from a heigh t of 750 mm, free fall of the container without rotational 
or sideways motion of the container.  
 DKS 2912 : 2020 
 
             © KEBS 20XX — All rights reserved  6 5.4.1.2 Impact  surface, comprising a rigid and level concrete surface (or a steel plate embedded in concrete) 
of sufficient strength and rigidity to withstand repeated impacts of test material without significant deflection 
or movement.  
 
5.4.2 Test  specimens  
 
Take, at random, two of the remaining containers from the sample under test (see A.2.2.2 of  Annex A ). 
 
5.4.3 Procedure  
 
So position one of the containers u pright that, when released, it will fall on its base. Operate the release 
mechanism and drop the con tainer .  Unless the container has failed, invert it, gently  distribute the contents 
as symmetrically as possible and repeat the drop. Repeat this procedure with the container positioned on its 
right-hand side and on its left -hand side.  
 
Repeat the test on the second container .  If a container fails, take a new container from the  remainder of the 
sample under test (see A.2.2.2 of Annex A ), and repeat the proce dure.  
 
For each container determine, as in5.2 or 5.3  (as relevant ), the  percentage (by mass) of the  contents that 
passed through a 9. 5 mm test sieve.  
 
5.6  Moisture content  
 
5.6.1 Principle  
 
A test specimen is heated to a constant mass in an air-oven at a temperature of 105 °C and the percentage 
moisture content is calculated from the loss in mass of the  test specimen.  
 
5.6.2 Apparatus  
 
5.6.2.1 Air  oven, capable of maintaining a substantially uniform temperature of 105 °C, and such that the ra te 
of atmosphere change is sufficiently rapid for the test.  
 
5.6.2.2 Balance , accurate to 1. 0 g. 
 
5.6.2.3 Tray , of area approximately 0. 1 m2 and of depth 25 mm, made of non -corrodible material such as 
stainless steel, tinned steel or aluminium. The tray shall be clean, dry and accurately tared.  
 
5.6.3 Test  specimen  
 
Approximately 500g ms in triplicates of charcoal  or carbonized briquettes . For the test on briquettes, take at 
random a similar number of unbroken briquettes from each container retained in terms o f 5.3.3 until 
approximately 500 g is obtained and, for the test on charcoal , take a test mass of 250 g from the c ontents of 
each container retained in terms of 5.2.3.  
 
 
5.6.4 Procedure  
 
Determine the mass m1 of the dry empty tray. Transfer the specimen as completely as possible to the tray 
and spread the specimen evenly.  Determine the initial mass m2 of the tray and contents. Place the charge d 
tray in the oven, preheated to 105 °C, until constant mass is obtained. Determine the mass m3 of the heated 
tray and contents while they are still hot, to avoid absorption of moisture during cooling.  
 
5.6.5 Expression  of results  
 
5.6.5.1 The  moisture con tent M of the charcoal, expressed as a percentage (by mass), is given by the 
equation  
 
M=𝑀2−𝑀3
𝑀2−𝑀1x100  
 
Where; DKS 2912 : 2020 
 
© KEBS 20XX — All rights reserved      v       7 
  
m1 = mass of the empty tray, in grams;  
 
m2 = initial mass of the tray plus the test specimen, in grams;  
 
m3 = mass of the tray plus the test specimen after heating, in grams.  
 
Report the result (preferably the mean of duplicate determinations) to the nearest 0,1 % (by mass).  
 
5.6.5.2 Check  for compliance with 4.5.1.  
 
5.6.6 Precision  of results  
 
The results of triplicate determinations s hall not differ by more than the appropriate of the values given in 
table 1.  
 
Table 1 — Precision of results  
 
5.7  Preparation  of test material for volatile matter content and ash content  
 
Take, at random, eight of the unbroken briq uettes (four from each container) retained in terms of5.3.3 or, in 
the case of charcoal , a specimen of mass at least 200 g from the contents of each container retained in terms 
of 5.2.3. Quickly (to avoid heat build -up) pulverize or grind the specimen such  that it passes through a 250 µm 
sieve, mix well, and store in an airtight container.  
 
5.8  Volatile matter content  
 
5.8.1 Principle  
 
A test specimen from which the moisture content has been extracted, is heated for 7 min at 900 °C out of 
contact with air.  The percentage of the volatile matter is calculated from the loss in mass of the test 
specimen.  
 
5.8.2 Apparatus  
 
5.8.2.1 Muffle furnace, heated by electricity, in which a zone of adequate size is maintained at a constant 
and uniform temperature of 900 °C  ± 10 °C. The furnace may be of the stop -ended type, or fitted at the back 
with a flue of diameter approximately 25 mm and of length approximately 150 mm.  
 
The heat capacity of the furnace is such that, with an initial temperature of 900 °C, a minimum temp eratu re 
of 885 °C is regained within 4 min (and preferably within 3 min) of the insertion of a cold stand and its 
crucible(s), the temperature being measured with the unsheathed thermocouple (see 5.8.2.2) by inserting its 
thermojunction midway between the floor of the furnace and the base of the crucible in its stand. If the stand 
holds more than one crucible, the temperature under each crucible is checked in the same manner.  
 
Normally, the furnace will have been designed specifically for receiving either o ne cr ucible and its stand or a 
number of crucibles in one stand.  
 
NOTE 1   The position of the crucible stand is chosen within the zone of uniform temperature and this 
position is used for all determinations.  
 
DKS 2912 : 2020 
 
             © KEBS 20XX — All rights reserved  8 NOTE 2   The temperature of 900 °C is attained  as closely as possible and the tolerance of ± 10 °C is 
specified to compensate for inherent errors in the temperature measurement and lack of uniformity in the 
temperature distribution.  
 
5.8.2.2 Where applicable, pyrometer, with an unsheathed thermocoupl e, of wire of diameter not exceeding 1 
mm, for checking the temperature characteristics of the muffle furnace.  
 
NOTE 1   A sheathed thermocouple can be permanently installed in the furnace with its thermojunction as 
close as possible to the centre of the z one o f uniform temperature. In this case, its temperature readings are 
correlated at frequent intervals with those of the unsheathed thermocouple. (Because of the thickness of the 
sheathed thermocouple, it cannot be inserted under a crucible.)  
 
NOT E 2 The tempe rature /electromotive force relationship of a thermojunction maintained at elevated  
temperatures gradually changes with time.  
 
5.8.2.3 Cylindrical crucible, with a well -fitting lid, both made of fused silica. The crucible and lid have a 
combined mass o f between 10 g and 14 g, and their dimensions approximate those shown in figure 1.  
 
The fit of the lid to the crucible is critical for the determination and a lid is so selected to match the crucible 
that the gap between the lid and the  crucible does not e xceed  0.5 mm. After selection, the crucible and the 
lid are ground together to give smooth -fitting surfaces and are thereafter used solely as a matched pair.  
 
NOTE   Crucibles of other refractory materials or of platinum may be used, provided that they giv e, within the 
prescribed limits of precision (see 5.8.6), the same results as the silica crucibles.  
 
5.8.2.4   Suitable stand, in which to place the crucible(s) in the muffle furnace, and such that the appropriate 
rate of heating can be achieved.  
 
5.8.2.5 Desiccant , of fresh or freshly regenerated self -indicating gel.  
 
5.8.2.6 Desiccator , of suitable dimensions, that contains the desiccant.  
 
5.8.2.7 Analytical  balance, accurate to within 0. 1 mg.  
 
5.8.2.8 Stopwatch . 
 
 
 
 DKS 2912 : 2020 
 
© KEBS 20XX — All rights reserved      v       9 
  
 
 
 
Figure 1 — Silica crucible and li d 
 
5.8.3 Test  specimen  
 
A test specimen taken from the material prepared in accordance with 5.7. Ensure that the pre -prepared 
material is thoroughly mixed (preferably by mechanical means) for at least 1 min.  
 
5.8.4 Procedure  
 
Heat the crucib le and lid (or the set of crucibles and lids (as relevant)) in the muffle furnace at  
900 °C ± 10 °C for 7 min. Remove the crucible(s) from the furnace, allow to cool on a thick metal plate for 10 
min and then for 15 min in the desiccator located next to th e balance.  
 
When cooled to room temperature, d etermine (in turn) the mass m1 of each clean empty cru cible and lid, to 
the nearest 0. 1 mg, and return the lid to the desiccator. Weigh, to the nearest 0 .1 mg, into each crucible, 
1.00 g to 1. 01 g of the test specimen, and he at the crucible and test specimen, without the lid, in an air oven 
(see 5.6.2.1) at 105 °C for 1 h. (This initial action is critical, since the result has to be expressed on a dry 
basis.) Cool the crucible and test specimen in the desi ccator for  
15 min. Re place the lid and determine, to the nearest 0. 1 mg, the initial mass m 2 of each crucible plus lid 
plus dried specimen.  
 
Tap each crucible on a clean, hard surface until the specimen forms a layer of uniform thickness at the 
bottom of t he crucible.  
 
Place t he charged crucible(s) in the stand and, in the case of multiple determination, fill the vacant places in 
the stand with empty crucibles. Place the stand within the zone of uniform temperature in the furnace, 
preheated to 900 °C, for e xactly 7 min, remove the crucible(s), allow to cool on a thick metal plate for 10 min 
and then in the desiccator for 15 min. When the crucible(s) has (have) cooled to room temperature, 
determine the mass of each ch arged crucible to the nearest 0. 1 mg and r ecord the final mass m3 of each.  
 
DKS 2912 : 2020 
 
             © KEBS 20XX — All rights reserved  10 NOTE   Precisely similar treatment of a crucible before and after determination minimizes the effect of any 
film of water absorbed on its surface, and the rapid cooling reduces absorption of moisture by the charcoal 
residu e. 
 
5.8.5 Expression  of results  
 
5.8.5.1    The volatile matter content V, expressed as a percentage (by mass), is given by the  equation  
 
V=𝑀2−𝑀3
𝑀2−𝑀1x100  
 
Where; 
 
m1    is the mass of the empty clean crucible plus lid, in grams;  
 
m2    is the mass of the crucible plus lid plus specimen after drying at 105 °C for 1 h, in grams;  
 
m3    is the mass of the crucible plus lid plus residue aft er heating, in grams.  
 
Report the result (preferably the mean of duplicate determinations), to the nearest 0,1 % (by m ass).  
 
5.8.5.2 Check  for compliance with 4.5.2.  
 
5.8.6 Precision  of result  
 
The results of duplicate determinations shall not differ by mo re than the appropriate of the values given in 
table 2.  
 
Table 2 — Precision of results  
 
 
5.9  Ash content  
 
5.9.1  Principle  
 
A test specimen from which the moisture content has been extracted, is heated in air at a specified rate up to 
a temperature of 7 10 °C ± 10 °C and maintained at this temperature until constant in mass. The percentage 
of the ash is calcula ted from the mass of the residue after incineration.  
 
5.9.2  Apparatus  
 
5.9.2.1 Analytical  balance, accurate to within 0. 1 mg.  
 
5.9.2.2   Muffle fu rnace, capable of giving a zone of substantially uniform temperature at the temperature 
levels required by th e procedure and of reaching these levels in the specified times. The ventilation through 
the muffle furnace should be such as to give more than fiv e air changes per minute.  
 
NOTE   The number of air changes per minute can be assessed by measurement of the air flow from the muffle furnace 
flue, using a pilot -static tube and a sensitive manometer.  
 
5.9.2.3 Dish , of silica, porcelain or platinum, of dep th 8 mm to 15 mm. The diameter of the dish is such that 
the surface (mass) density of the s pecimen layer does  not exceed 0. 15 g/cm2.  
 
DKS 2912 : 2020 
 
© KEBS 20XX — All rights reserved      v       11 
 5.9.2.4 Insulating  plate, of silica of thickness 6 mm, or of heat -resistant steel of such size as to be an easy 
sliding fi t into the muffle furnace (see 5.9.2.2).  
 
5.9.2.5 Desiccant , of fresh or freshly regenerated self -indicating gel. 
 
5.9.2.6 Desiccator , of suitable dimensions, that contains the desiccant.  
 
5.9.3 Test  specimen  
 
A test specimen taken from the material prepar ed in accordance with 5.7. Ensure that the prepared material 
is thoroughly mixed (preferably by mechanical means) for at least 1 min.  
 
5.9.4 Procedure  
 
Heat the dish (see 5.9.2.3) in the muffle furnace to 710 °C ± 10 °C and maintain it at this  temperature for 15 
min. Remove the dish from the furnace and allow the dish to cool on a thick metal plate f or 10 min and then 
for 15 min in the desiccator located next to the balance. When cool, determine the mass m1 of the dish to the 
nearest 0,1 mg.  
 
Spread ± 1 g o f the test specimen evenly in the dish and heat the dish and test specimen in an air oven (see 
5.6.2.1) at 105 °C for 1 h.   (This initial action is critical, since the result has to be  expressed on a dry basis.) 
Cool the dish and test specimen in the desic cator for 15 min. Determine the initial mass m2 of the dish plus 
dried specimen to the nearest 0 ,1 mg.  
 
Place the dish, plus test specimen, in the cold muffle furnace and raise the temperature to 250 °C  
within 30 min, then from 250 °C to 500 °C within anot her 30 min, and finally from 500 °C to 710 °C  
± 10 °C within 60 min.  
 
When incineration is compl ete, remove the dish plus test specimen from the furnace, and allow to cool on a 
thick metal plate for 10 min and then in a desiccator for 15 min. When the dish  and test specimen have cooled, 
determine the mass m 3 of the dish plus incinerated test specimen  to the nearest 0,1 mg.  
 
Reheat at 710 °C ± 10 °C for further 15 min periods, allow to cool, and determine the mass until any change 
in mass does not exceed 1 m g. 
 
5.9.5 Expression  of results  
 
5.9.5.1 The  ash content A, expressed as a percentage (by mass),  is given by the equation  
 
A=𝑀3−𝑀2
𝑀2−𝑀1x100  
 
 
Where; 
 
m1    is the mass of the dish, in grams;  
 
m2    is the mass of the dish plus specimen after drying at 105 °C for 1 h, in grams;  
 
m3    is the mass of the dish plus ash after incineration, in grams.  
 
Report the result, as the arithmetic mean of duplicate determinations, to the nearest 0,1 % (by mass).  
 
5.9.5.2 Check  for compliance with 4.5.3.  
 
5.9.6 Precision  of results  
 
The results of duplicate determinations shall not differ by more than the appropriate of the values given in  
table 3.  
 
 
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             © KEBS 20XX — All rights reserved  12 Table 3 — Precision of results  
 
 
 
5.10  Fixed  carbon content  
 
5.10.1  Principle  
 
The fixed carbon is the carbon that remains after the removal of the volatile matter content and the ash 
content in accordance with 5.8 and 5.9 respectively.  
 
5.10.2  Expression  of results  
 
5.10.2.1   The fixed carbon content FC, expressed as a percentage (by mass), is given by the equation  
 
FC=100−(𝐴+𝑉+𝑀𝑐) 
 
Where; 
 
A   is the ash content determined in ac cordance with 5.9, as a percentage (by mass);  
 
V   is the  volatile matter content determined in accordance with 5.8, as a percentage ( by mass) , 
 
Mc is the moisture content  determined in accordance with 5.6, as a percentage (by mass) . 
 
5.10.2.2 Check  for compliance with 4.5.4.  
 
5.11  Test report  
 
The test report shall contain the following particulars:  
 
a) the identification of the product or sample tested;  
b) a reference t o this standard;  
c) the test results;  
d) any deviations from the test methods in this standard;  
e) any unusual features noted during the deter minations; and  
f)  the date(s) of the tests.  
 
6  Packing  and marking  
 
6.1  Packing  
 
Sustainable Charcoal  and briquettes shall be packed and sealed  in; 
 
a) multi -wall bags , corrugated board containers  or any suitable packaging material such as to be accepta ble 
to maintain product integrity . 
 
b) units of 1 kg to 50 kg  as required . 
 
 
6.2  Marking  
 
Each container sha ll be legibly and indelibly marked with the following information:  
 
DKS 2912 : 2020 
 
© KEBS 20XX — All rights reserved      v       13 
 a) the manufacturer’s name or trade name or trade mark;  
 
b) the description of the contents of the container, i.e. " Carbonized briquettes "; 
 
c) the batch identification or the date of pack ing (which may be in code);  
 
d) the net mass of the contents;  
 
e) Country of origin;  
 
e) raw material used e.g. char dust; and source  
 
f) handling  and storage information  
 
g) Information on u sage  specifying that  it should be used under a well-ventilated  environment ; and  
 
f) any additional information, as required (see A.1 (d) of annex A).  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DKS 2912 : 2020 
 
             © KEBS 20XX — All rights reserved  14 Annex A 
(normative)  
Quality verification of charcoal and carbonized briquettes  
 
A.1 Quality  verification  
 
A.1.1    When a purchaser requires on-going  verification of the quality of  sustainable  charcoal and  carbonized 
briquettes  produced to this standard, it is suggested that instead of concentrating solely on the evaluation of 
the final product, he also direct his attention to the manufacturer’s quality system. In this connection it should 
be noted that KS IS O9001 covers the pro vision of an integrated quality system.                                                                                                                                                        
 
A.1.2 If  no information about the implementa tion of quality cont rol or testing during manufacture is available to 
help in assessing the quality of a lot, and a purchaser wishes to establish, by inspection and testing of samples 
of the final product, whether a lot (see A.2.1.2) of the product complie s with this standard , use the sampling 
plan given in A.2.2.                                                                           
 
NOTE 1   The sampling plan applies to the final product only.  
 
NOTE 2   A lot that in terms of the sampling plan is deeme d to comply with the  standard, could contain  defective 
charcoal and carbonized briquettes . 
 
In cases of dispute, the lot shall be available for inspection by the Kenya  Bureau of  
Standards.  
 
A.2 Assessment  of compliance  
 
A.2.1 Definitions  
 
A.2.1.1 defective  
Charcoal that fails or carbonized briquettes  that fail, in one or more respects, to comply with the relevant 
requirements of this standard  
 
A.2.1.2 lot  
The quantity of charcoal or carbonized briquettes  of the same form, packed in containers of the same ty pe and 
size, and bearing the same batch identification or date of packing, from one  
manufacturer, and submitted at any one time for inspection and testing  
 
A.2.2 Sampling  
 
The following sampling procedure shall be used to determine whether a lot complies with the requirements of 
this standard. The sample so taken shall be deemed to represent the lot for the respective properties.  
 
A.2.2.1 Sample  for inspection  
 
From the lot, draw at random the greater of the following numbers of containers:  
 
Twelv e containers or the number of containers calculated (to the nearest whole number) by the following:  
√𝐴
2 
 
Where; 
 
A   is the number of containers in the lot.  
 
A.2.2.2 Sample  for testing  
 
After inspection of the sample taken in accordance with A.2.2.1, take from it, at random ,10 containers.  
 
A.3 Criteria  of compliance  
 DKS 2912 : 2020 
 
© KEBS 20XX — All rights reserved      v       15 
 The lot shall be deemed to comply with the relevant requirements of the standard if, after inspection and testing 
of the sample taken in accordance with A.2.2, defect does not exceed 1 container of sample.  
 
 
 