UGANDA STANDARD  
  DUS 1643:2016  
First Edition  
2016 -03-02 
 
 
 Reference n umber  
DUS 1643 : 2016 
© UNBS 2015   
  
Domestic biogas lamp — SpecificationDUS 1643 : 2016  
ii © UNBS 2016  – All rights reserved  
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are responsible for its 
correct appli cation  
© UNBS 200 7  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any form or by any means, 
electronic or mechanical, including photocopying and microfilm, without prior written permission fro m UNBS.  
Requests for permission to reproduce this document should be addressed to  
The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
Kampala  
Uganda  
Tel: 256 41 4 505 995  
Fax: 256 41 4 286 123  
E-mail: unbs@infocom.co.ug  
Web: www.unbs.go.ug  DUS 1643 :2016  
© UNBS 2016  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ................................  v 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ................................ .. 1 
4 Technical requi rements  ................................ ................................ ................................ ........................  2 
4.1 Performance requirements  ................................ ................................ ................................ ...................  2 
4.1.1  Rated pressure  ................................ ................................ ................................ ................................ ...... 2 
4.1.2  Specified heat load  ................................ ................................ ................................ ................................  2 
4.1.3   Burning stability  ................................ ................................ ................................ ................................ ... 2 
4.1.4  Luminance  ................................ ................................ ................................ ................................ ..............  2 
4.1.4  Lighting efficiency  ................................ ................................ ................................ ................................ . 2 
4.1.5  Content of CO in disposal of smoke  ................................ ................................ ................................ ... 2 
4.1.6  Time of igniting  ................................ ................................ ................................ ................................ ...... 3 
4.1.7  Noise of burning  ................................ ................................ ................................ ................................ .... 3 
4.1.8  Surface temperature  ................................ ................................ ................................ ..............................  3 
4.1.9  Glass mantle  ................................ ................................ ................................ ................................ ..........  3 
4.2  Requirements of structure  ................................ ................................ ................................ ..................  3 
4.3 Requirements of the materials  ................................ ................................ ................................ .............  4 
5 Test m ethods  ................................ ................................ ................................ ................................ .........  4 
5.1 Test conditions.  ................................ ................................ ................................ ................................ ..... 4 
5.2 Test of gas use.  ................................ ................................ ................................ ................................ ..... 4 
5.3 Appar atus and system for testing  ................................ ................................ ................................ ....... 4 
5.4 The test content and method  ................................ ................................ ................................ ...............  6 
5.4.4  Stability of burning  ................................ ................................ ................................ ................................  6 
5.4.5  Luminance and lighting efficiency  ................................ ................................ ................................ ...... 6 
5.4.6  CO content in exhausted smoke  ................................ ................................ ................................ ..........  7 
5.4.7  Noise  ................................ ................................ ................................ ................................ .......................  7 
5.4.8  Surface temperature  ................................ ................................ ................................ ..............................  8 
5.4.9  Glass mantle  ................................ ................................ ................................ ................................ ..........  8 
6 Regulations of tes t ................................ ................................ ................................ ................................  8 
6.1 Ex-factory check  ................................ ................................ ................................ ................................ .... 8 
6.2 Model test  ................................ ................................ ................................ ................................ ...............  8 
6.3 Classification o f items and identification  ................................ ................................ ...........................  9 
6.4 Sample size  ................................ ................................ ................................ ................................ ............  9 
7  Process quality control  ................................ ................................ ................................ ........................  9 
7.1 Quality checking during manufacturing  ................................ ................................ .............................  9 
7.2 Quality plan  ................................ ................................ ................................ ................................ ..........  10 
8 Workmanship and finish  ................................ ................................ ................................ .....................  10 
9 Sampling  ................................ ................................ ................................ ................................ ..............  10 
9.4 Random sampling  ................................ ................................ ................................ ...............................  11 
9.5 Sampling plan for visual inspection and dimensi onal check  ................................ .........................  11 
9.5.1  Sampling plan  ................................ ................................ ................................ ................................ ...... 11 
9.5.2  Criteria for conformity ................................ ................................ ................................ .........................  11 
10 Marking  ................................ ................................ ................................ ................................ .................  11 
11 Packing  ................................ ................................ ................................ ................................ .................  12 
Annex  A (normative)  Illustration of General Biogas Lamp Parts  ................................ ...............................  13 
A.1 General Features  ................................ ................................ ................................ ................................ . 13 DUS 1643 : 2016  
iv © UNBS 2016  – All rights reserved  
 Annex  B (informative)  Biogas Combustion  ................................ ................................ ................................ . 14 
B.1 Combustion  ................................ ................................ ................................ ................................ .........  14 
B.2 Flame  ................................ ................................ ................................ ................................ ....................  14 
Bibliography  ................................ ................................ ................................ ................................ .....................  16 
 DUS 1643 :2016  
© UNBS 2016  – All rights reserved  v 
 Foreword  
Uganda National Bureau of Standards (UNBS) is a parastatal unde r the Ministry of Trade , Industry and Cooperatives established 
under Cap 327 , of the Laws of Uganda.  UNBS is mandated to co -ordinate the elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point  for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT/SPS Agreements of the World Trade Organisation (WTO).  
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical C ommittee is established to 
deliberate on standards in a given field or area and consists of representatives of consumers, traders, academicians, manufac turers, 
government and other stakeholders.  
Draft Uganda Standards adopted by the Technical Committee are  widely circulated to stakeholders and the general public for 
comments. The committee reviews the comments before recommending the draft standards for approval and declaration as Uganda 
Standards by the National Standards Council.  
Committee membership  
 
 UGANDA STANDARD  DUS 1643 : 2016  
 
© UNBS 2016  – All rights reserved  1 
 Domestic Biogas Lamp — Specification  
1 Scope  
This Uganda Standard covers construction, operation, safety requirements , sampling  and methods of test for 
lamps intended for use with biogas.  
2 Normative references  
The following referenced documents are indis pensable 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.  
CD-ENG -12: 2012, Biogas — Glossary, and fundament al principle  
3 Terms and definitions  
For the purposes of this Ugand a Standard the following  terms and definitions , including the terms given in 
DUS  1641 , shall apply . 
3.1 
Air sleeve  
a sleeve with a number of air holes, which can be rotated to adjust and v ary the gas and air ratio in the mantle 
holder  
3.2  
Lamp  
a device used to generate light by combustion of the gas  
3.3  
Mantle holder  
a part of the lamp, which is fitted with the carbor undum ventur i where a mantle can be fitted. The holder  
consists of g as nozzle for the flow of the gas for combustion and air holes for  proper mixing of gas and air.  
3.4  
Reflectors  
Pieces  of glass, metal, or other material  fitted on top of the lamp for reflecting heat and light in a required 
direction so that heat and lig ht produced at the mantle is reflected below and the flow of heat through the lamp 
top is retarded   
2 © UNBS 2016  – All rights reserved  
 4 Technical requirements  
4.1 Performance requirements  
4.1.1 Rated pressure   
The rated pressure shall be 2400 N/m2, 1600 N/m2 and 800 N/m2 respectively.  
4.1.2 Specified heat load  
The specified heat l oad will not be over 525 W (450 kcal/h) while the minimum is 410W (350 kcal/h).  
4.1.3  Burning stability  
Under the specific pressure at the heat value being 19  MJ/m3 (4500  kcal/m3) and 25MJ/m3 (6000  kcal/m3) the 
lamp should be flaming in a stable conditi on. 
Under the 50 % specific pressure the biogas lamp should not be flaming back, while under the 150% specific 
pressure flaming should not be seen. While burning under the specific pressure the range of luminance 
fluctuating should not be over ±10 %.  
4.1.4 Luminance  
Under the three different specific pressures the luminance should not be less than the figures in Table 1 as 
below.  
Table 1 — Luminance  
Pre-lamp pressure, 
N/m2   2400  1600  800 
Luminance, lx  60 45 35 
 
4.1.4 Lighting efficiency  
Lighting efficiency is one of the parameters  for indicating the economic effect of light sources. The lighting 
efficiency of the biogas lamp is the ratio of luminance to heat load with the unit being lx/W.   
Under the rated pressure of pre -lamp the shining efficiency should not be less than the figure in Table 2.  
Table 2 — Lighting efficiency  
Pre- lamp  2400  1600  800 
Shining Efficiency, 
Lx/W  0.13 0.10 0.08 
 
4.1.5 Content of CO in disp osal of smoke   
When the lamp is working under the rated heat load, the CO ( α= 1) content in the disposal of smoke is not 
more than 0.05%.  DUS 1643 : 2016  
© UNBS 2016  – All rights reserved  3 
 4.1.6 Time of igniting   
The time from the mantle is burning at the rated pressure (except the mantle for the first igniting) to giving light 
should not be over 20 sec.  
4.1.7 Noise of burning  
When the lamp is working under the 150 % rated pressure the burning noise should not be more than 55dB.  
4.1.8 Surface temperature  
When the lamp is working at the 150 % rated pressure the surface temperature at the jet connecting to the 
pipe should not be o ver the room temperature plus 50 °C.   
4.1.9 Glass mantle  
The dropping rate of luminance through the glass m antle should not be over 20 %.  
Resistance to sudden change of temperature: at the temperature T = 80 °C, no cracks appear for two times of 
sudden te mperature drop.  
4.2  Requirements of structure  
4.2.1  The leaning rate  of the central hole for the jet should not be more than 0.2mm, and the mantle jet 
should be protected with necessary measures.  
4.2.2  The burner of the lamp should be strong and durabl e with air -tightness. The inner wall of the jet 
should be smooth without burrs.  
4.2.3  The muddy head (i.e. head of burner) should not be with cracks if pottery products are used.  
4.2.4  After the assembling of the lamp the leaning difference between the j et mouth and the axes of the 
mixing tube for the jet should not be more than 0.2 mm.  
4.2.5  The switch and air adjustment board or the air -intake hole should be flexible and easy to operate. 
Once it is fixed on position it should not be movable.  
4.2.6  For the biogas lamp with rated pressure of 2400 N/m2 and 1600 N/m2 , No150 yarn mantle is 
selected; while for that of 800 N/m2, No.200 yarn mantle is used.  
4.2.7  The requirements of the size and look for the glass mantle:  
a) The geometric dimension of the glass  mantle is met according to the general structure of the lamp;  
b) The height difference between the upper and lower mout hs of the glass mantle should not be more 
than ±0.5  mm; 
c) The out-off roundness of the upper and lower mouths of the glass mantle should not be more than 
±0.5 mm;  
d) Both the upper and lower mouths for the mantle should be smooth without cuts;  
e) The thickness of the mantle should be even with the difference not more than 0.5  mm. 
f) The shortcoming for the glass mantle should meet the following requirem ents:  
i. Gas bobble of over 1.0  mm is not allowed, that of less than 1.0  mm should not be too dense. 
Within the space of 20  mm x 20  mm no more than three bobbles are allowed.   
4 © UNBS 2016  – All rights reserved  
 ii. It is not allowed to be existing for calculi and sand of over 1.0  mm, and to be den se for those 
less than 0.5  mm. Within the space of 20  mm x 20  mm no more than three are allowed.  
iii. Obvious stripes are not allowed.  
4.2.8  The reflecting cover of the lamp should be smooth on the surface with smoke exhaust hole. The cover 
and the burner shou ld be installed hardly.   
4.3 Requirements of the materials  
4.3.1 The jet mouth should be made of metal material wi th melting point being over 500 °C. 
4.3.2 The burner should be made of metal material wi th melting point being over 700 °C. 
4.3.4 The sealing materials contacting biogas and the lubrication agent for the switch should be suitable for 
the features of biogas.  
4.3.5 The reflecting cover of the lamp should be made of materials of heat resistance at least 500oC, higher 
coefficient of surfa ce reflecti on of at least 40%.  
4.3.6 The materials used shall comply with the relevant Uganda or International Standards.  
5 Test methods  
5.1 Test conditions . 
5.1.1 The temperature at the lab  should be kept between 15 – 25°C. During the test process the fluctuation 
of the room temperature should be less than ±3 °C. And the content for the CO in the room should be less 
than 0.002 %. The air flow rate should be not more than 0.5m/s while the humidity in the air should be 
controlled under 80 %.  
5.1.2 In the test system it  should be installed with high -pressure biogas storage cylinder and pressure 
adjustment equipment. During the test process the fluctuation of the pressure should not be more than ±20  
Pa. 
5.1.3 In the test system it should be installed with high -pressure bi ogas storage cylinder and pressure 
adjustment equipment. During the test process the fluctuation of the pressure should not be more than ±20  
Pa. 
5.1.4 The luminance of the biogas lamp should be tested in a special dark room or box, while the inner wall 
of which should be white. The base luminance value should be zero.  
5.2 Test of gas use . 
The low heat value of man -made biogas is fixed as 21 MJ/m3 ±1 MJ/m3 (stan dard volume) (5250 Kcal/m3 
±240 Kcal/m3).  
5.3 Apparatus and system for testing  
5.3.1 The apparatus  for testing should be stipulated as in Table 3 and checking and adjustment should be 
done before testing.  
 
 DUS 1643 : 2016  
© UNBS 2016  – All rights reserved  5 
 Table 3 — Accuracy of measuring equipment  
 Testing item  Name of apparatus  Specification  Precision  
1.  Temperature of biogas and 
indoor  Glass, alcohol  and 
thermometer  0 -500 C 0.50C 
2.  Biogas pressure  U-type pressure meter  ±5000Pa  10Pa  
3.  Biogas flow  Wet-type gas -flow 
meter  0.5m3/h  0.2L 
4.  Atmosphere pressure  Box-type gas pressure 
meter  81-107kPa  0.1kPa  
5.  Time  Watch of second  15 min  0.2sec.  
6.  Luminance  Luminance meter  0.1-199 900lx  0.1lx  
7.  Smoke content   Gas chromatograph & 
Infrared -CO analyzer    
8.  Heat value of biogas  Water -flow type, 
thermo flow -meter    
9.  Surface temperature  Surface thermometer  0—200 °C  2 °C 
10.  Noise   Sound meter  
 40-140dB - human 
audible range   0.5dB  
11.  Glass -cover with sudden 
temperature change  Constant temperature 
oven  0-150 °C  2 °C 
12.  Wind speed  Hot-ball breezing 
instrument  0-5m/s  0.2m/s  
13. NOTE  Testing gas: 21± 1 MJ/m3    (60 % CH4 + 40 % CO2)  
 
5.3.2  The test system is seen in Figure 1.  
 
 
Figure 1 —Biogas lamp testing set up   
6 © UNBS 2016  – All rights reserved  
 5.4 The test content and method   
5.4.1 Check the structure, dimensions, materials and processing preciseness and installation to see if they 
meet the requiremen ts of drawings and technology.  
5.4.2 Check of air-tightness  from the intake of gas to jet mouth when the valve is at the position of open 
(shut the jet mouth) and close, and under the pressure of 10,000 Pa (1000mmH 2O) for 1min, the reading of 
the U -type pressure meter should not drop.  
5.4.3 Heat load  Switch on the lamp at the rated pressure and adjust the lamp to the optimum condition and 
let it burn for 10 minutes, then record the initial reading on the gas flow -meter. At the same time timing starts 
until 6 minutes to record the final reading to seek out the difference value.  
The rated heat load at the standard pressure is  calculated by conversion of the following formula (1):  
2 1
0 00
0 . . ffPPPP
tTTQVIv g a









               (1) 
Where:  
I0 Heat load of the lamp, W;  
V Wet biogas flow detected by the flow meter, m3/h;  
Q Low heat value under the standard state,  KJ/m3;  
T0 Temperature of thermostatic of biogas u nder the standard state, 273K;  
l Temperature of biogas at the out let of the gas flow -meter, °C;  
Pa Atmos phere pressure at the lab, Pa;  
Pv Steam branch pressu re from biogas at the outl et of the gas flow -meter, Pa;  
Po Standard atmosphere, 101325Pa;  
f1 Revised coefficient of the flow -meter;  
f2 Conversion coefficient of heat unit, 0.277 78  
5.4.4 Stability of burning  
Under the rated pressure of 0.5 times switch on the lamp and observe if there i s fire back within 10 minutes.  
Under the rated pressure of 1.5 times and observ e if there is flame appearing.  
Under the rated pressure and at the 0.95 m from the yarn mantle to test the max imum a nd min imum . 
luminance of the b iogas lamp. Compare with the average luminance the value should not be over ±10%.  
5.4.5 Luminance and lighting efficiency   
The biogas lamp should be installed with a glass mantle and adjusted with proper amount of air intake. After 
10 minutes of ignition u ntil the luminance get to the optimum value test the luminance in a normal way.  
At the four selected points on the circle of 0.95  m vertical from the hanging lamp and 0.31  m in radius put the 
photo -sensitive elements of the luminance meter pointing to the lamp, the mean luminance at the four points 
should not be lower than th e stipulated value in Table 1.  DUS 1643 : 2016  
© UNBS 2016  – All rights reserved  7 
 Put the photo -sensitive elements as at the horizontal distance of 0.95  m from the desk biogas lamp on the 
random four points of the circle with 0.31  m in radius, the average luminance on the four points should not be 
less than th e stipulated value in Table 1.  
Make the comparison between the luminance of the lamp and the heat load of the light source, the lighting 
efficiency should not be lower than the stip ulated value in Table 2.  
The lighting efficiency is figured out by the following formula (2):  
N= E
Ov
IE                     (2) 
Where:  
N Lighting efficiency, lx/W;  
Ev Luminance   
I0 Heat load of the lamp, W.   
The test should be done at  least for two times. The final result is from the average value detected and the 
relative error for each time value  =
MeanValueMin Max  should not be over 5 %. Otherwise do it again.  
5.4.6 CO content in exhausted smoke  
While detecting the luminance of the lamp, use a ring -type sample collector to put it above 3 -5 mm of the yarn 
mantle. It is forbidden to touch flame. The speed for take the smoke is 0.5  - 1 L/min, and the oxygen content in 
the s ample should not be over 12 %.  
The ring -type sample colle ctor is made of copper or stainless steel tube with inner diameter of 3  mm and 
inner -wall of 1 mm. In the inner side of the ring -type tube it is evenly distributed with 12 gas intake holes, each 
of 0.5mm in diameter.   
While exhausting smoke the content of  CO is calculated as follows:  

9.20 19.20)1 (
22
OO CO COCOc b

               (3) 
Where:  
  CO(α=1)  As surplus air coefficient being 1, the Carbonmonoxide content of dry smoke, %;  
  COb   Carbonmonoxide content in the sample of smoke, %;  
  COc   Carbonmonoxide conte nt in the indoor air, %;  
  O2   Oxygen content in the sample of smoke, %  
5.4.7 Noise  
In the environment of base noise less than 45  dB switching on the lamp at the rated pressure of 1.5 times test 
the burning noise at 0.5  m in front of the lamp with Grade A  of a sound meter.   
8 © UNBS 2016  – All rights reserved  
 5.4.8 Surface temperature  
Igniting the lamp at the rated pressure of 1.5 times for 30 min, then detect the joint temperature between the 
jet mouse and plastic pipe.  
5.4.9 Glass mantle  
5.4.9.1  The detect ing of luminance dropping rate  
a) Under the rated pressure detect respectively the luminance with the glass mantle and without it, record the 
reading.   
b) Calculate the average value for three times according to the formula (4):  
10000LLgLLDR
                   (4) 
Where:  
  LDR  Luminance dropping rate (%)  
 L0  Luminance without glass mantle  
 Lg  Luminance with Glass mantle   
5.4.9.2  Detecting of resistance to sudden temperature change  
The temperature change of the oven with constant temperature is ±2 °C. At temperature △t ＝80 °C, put the 
glass mantle into the oven within 5 sec. After 5 minutes at stable temperature of 15  s ±1 s and cool it in the air 
to see if there is crack or not. Do the test for two times for the same sample.   
5.4.9.3  Check of g eometric dimension and  outlook  
Check gas bubble, calculi, all geometric dimensions by eyes and ruler. Take 30 samples randomly each time. 
When 8 % is not qualified take samples doubly. If it is still over 8 % not qualified, it means the whole batch is 
not qualified.  
6 Regulatio ns of test   
6.1 Ex-factory check   
The products should be checked by the authorized quality test department before being taken out the factory. 
For items of 4.1.2, 4.1.3, 4.1.4, 4.1.6, 4.1.7, 4.1.10, the products shall be tested at the delivery.   
6.2 Model test   
In case of any one of the following conditi ons it should take model test.  
a) After normal production if there is a big change of structure, materials an d production process, which may 
affect the character of the products;  
b) At the time of new pr oducts being appraised;  
c) When the production to be restarted after a long time stop;  DUS 1643 : 2016  
© UNBS 2016  – All rights reserved  9 
 d) In case the test result is of big difference at the ex -factory with that of the last model test;  
e) At the request of the monitoring authority to make the model test;  
f) For the continuous production such test should be done once a year;  
6.3 Classification of items and identification  
The classification of items and identification is seen in Table 4.  
Table 4 — Disqualification item classification and determination metho ds 
Clasification  Series  Item Mode of Identification  
A 1 Luminance  All items should be qualified  
2 Burning stability  
B 
 3 Igniting time   One unqualified item is allowed  
4 CO content in smoke exhausted   
 5 Dropping rate of luminance for the glass 
mantle   
 6 Character of the glass mantle on resisting 
sudden change of temperature   
C  Others  Five unqualified item is allowed  
 
6.4 Sample size  
The number of samples for quality test should not be less than three. If the results do not meet the 
requireme nts, do the test repeatedly with double sample quantity. If there is still one lamp which cannot meet 
the requirements in the result of the repeat test, it means the whole batch of the products is not qualified.   
7  Process quality control  
7.1 Quality chec king during manufacturing  
The manufacturer shall consistently check the quality of the product during various stages of its 
manufacturing. Quality control at following points are recommended, however depending upon the procedure 
followed the manufacturer m ay include other suitable points also:  
a) Raw material shall be checked to ensure that they conform to t he requirements of Clause 4.2.  
b) Mantle holde r shall be checked as follows:  
i. Diameter and concentricity of jet hole.  
ii. Quality and measurement of inside and out side thread  
iii. Length and diameter of sleeve  
iv. Position and diameter of air holes  
v. Quality of the machining.  
c) Air sleeve  shall be checked as follows  
i. Inside diameter of the sleeve   
10 © UNBS 2016  – All rights reserved  
 ii. Position and diameter of air holes.  
iii. Position and quality of handle. Quality of brazi ng 
d) Reflectors shall be checked as follows  
i. Position and diameter of central hole of upper reflector.   
ii. Position and diameter of holes for turning lock and hinges in upper reflector.   
iii. Position and diameter of holes for spoke, hinges for lower reflector   
iv. Centre distance between holes of lock holes and hinge holes.   
v. Dimensional measurements of lock set.   
vi. Quality of powder coat on the lower reflectors.  
e) Spokes and glass holder  shall be checked as follows  
i. Dimensional requirements of spokes.   
ii. Position and diam eter of holes on spokes.   
iii. Profile (V - shape) of spokes.   
iv. Dimensional requirements of glass holder.   
v. Quality of Powder coat on the spokes and glass holder  
f) The lamps shall be assembled completely to check the quality of fitting.  
7.2 Quality plan   
The sup plier shall prepare a quality plan describing exactly how the specification and other quality 
requirements specified in this standard will be met. The plan shall clearly specify different inspection/ control 
points. The supplier shall maintain records of d imensional checks, visual inspection and other tests carried as 
a proof of conformance of the product to the requirements of this standard. The supplier shall preserve and 
present these records whenever required.  
8 Workmanship and finish   
The finish and w orkman ship of the lamp parts shall be of high quality.  The surface of the lamp shall be 
smooth, without any blur, projections or protrusion. Any sharp e dge shall be suitably removed. There shall be 
no leakage of gas from threaded joints of the lamp assemb ly. 
9 Sampling   
This sampling plan shall be followed for any lot wise inspection of the products for the purpose of lot 
acceptance.  
9.1 Batch — all of the products cast from one melt shall constitute a batch.   
9.2 Lot — a number of products offered for i nspection at one time and manufactured from the raw material 
from same source shall constitute a lot. Maximum and recommended lot size shall be 500 sets of biogas 
lamp.   DUS 1643 : 2016  
© UNBS 2016  – All rights reserved  11 
 9.3 Defective sample, any sample not conforming to any one or more of the specified r equirements.  
9.4 Random sampling  
A random sampling method ensuring that every piece of products offered for inspection shall have equal 
probability for being selected as a sample shall be followed. Either of the two random sampling methods shall 
be followe d:   
(a) Systematic sampling   
(b) Use of random sampling table  
9.5 Sampling plan for visual i nspection and dimensional check  
9.5.1  Sampling plan  
Table 2 — Sampling plan  
Lot size  Sample size  Acceptance number  Rejection number  
(a) (b) (c) (d) 
1 – 15 2 0 1 
16 – 90 13 1 2 
91 – 150 20 2 3 
151 – 280 32 3 4 
281 – 500 50 5 6 
 
9.5.2 Criteria for conformity  
For the lot size specified in column (a) of the above table sample size specified in column (b) shall be 
inspected for visual and dimensional requirement s. If the number of defected samples is less or equal to the 
number mentioned in column (c) then the lot shall be considered conforming to the requirements of this 
standard in visual and dimensional requirements, if the total number of defective samples is  equal to or more 
than the number mentioned in column d then the lot shall be considered not conforming to the requirements of 
this standard.  
10 Marking  
Each biogas lamp shall be legibly and indelibly marked as following;  
10.1  Lower reflector of every la mp shall permanently be marked with the followin g information  
a) Manufacturers name/ or logo/ or any other identification  
b) Batch No  
c) Colour code.  
10.2 On the label of every individual packing:  
a) Model of the biogas lamp  
b) Rated pressure (Pa)  
c) Heat load (W)   
12 © UNBS 2016  – All rights reserved  
 d) Specif ication of the yarn mantle matched for the lamp  
e) The label shall be prepared in English.  
11 Packing   
11.1 Different parts of the biogas lamp shall be suitably packed. All parts except the glass shall then be 
packed inside a cardboard box. On the outside of  the box it should be marked with names of the manufacture, 
names of products, model, quantity, dimensions of the outlook, weight and ex -factory date. Further, it is also 
necessary to be marked with damp -proof, quakeproof and handle with care, glass produc ts easy to break etc. 
The box shall be securely s ealed with the label in place.  
11.2 Glass shall be separately packed in appropriate protective packing.   
11.3  Each product should be packed with quality certifica te and manual book.  DUS 1643 : 2016  
© UNBS 2016  – All rights reserved  13 
 Annex  A 
(normative)  
 
Illustration of General Biogas Lamp Parts  
A.1 General  Features  
Biogas can be burnt in lighting mantles. A biogas lamp consists of gas supply tube, a gas regulator, gas 
injector jet, primary air hole (s) or air regulator, a nozzle, a silk mantle, a lamp sha de and a glass shade 
(reflector). Schematic diagram of a biogas lamp is shown in Figure A.1.  
 
Mantles are normally made by saturating a ramie -based artificial silk or rayon fabric with rare earth oxides 
(cerium and thorium). It resembles a small net bag.  A binding thread made of ceramic fiber thread is provided 
for tying it onto the head. When heated at a temperature of more than 1000oC, the mantle glows brightly in the 
visible spectrum while emitting little infrared radiation. Fabric of the mantle, when flamed for the first time, 
burns away, leaving a residue of metal oxide. Therefore the mantle shrinks and becomes very fragile after its 
first use.   
In a lamp, the burning gas heats a mantle until it glows brightly. The key factors which determine the lum inous 
efficiency are the type and size of mantle, the inlet gas pressure and the fuel -air mixture. The hottest inner 
core of the flame, should match exactly with the form of the mantle. If the mantle body is too large, it will show 
dark spots. If the flame  is too large, then gas consumption will be too high for the light flux yield. If the inlet gas 
pressure is below 75 mm water column, the lighting is poor. The lighting is satisfactory if the gas pressure is 
above 100 mm water column and excellent at 150 m m water column. If the flame is too large, then gas 
consumption will be too high for the light flux yield. The maximum light flux values that can be obtained with 
biogas are 400 -500 lumens, corresponding to luminous efficiency in the range of 1.2 to 2.0 lm /W and 
equivalent to those of a normal 25 -75 W incandescent light bulb.  
  
14 © UNBS 2016  – All rights reserved  
 Annex  B 
(informative)  
 
Biogas Combustion  
B.1 Combustion  
Biogas burns in oxygen to give carbon dioxide and water and energy content in  methane is released.  
CH 4  + 2O2       CO 2  + 2H2O  + Energy  
Each m3 of biogas releases about 20 -24 MJ of energy. The oxygen required for combustion is taken from air, 
which contains approximately 21 per cent oxygen and 79 per cent nitrogen by volume. The  chemical reaction 
is depicted below:  
CH 4  + 2O2  + 7.5N2     CO 2  + 2H2O + 7.5N2 + Energy  
Thus, about 9.5 volumes of air per volume of combustion of methane are required to achieve complete 
oxidation. This is the stoichiometric methane -air mixture and is  the optimum concentration of methane in air at 
which complete combustion occurs without unused air or fuel. The combustion of biogas involves mixing of air 
with fuel gas, adding heat in the form of a pilot and burning the resultant air -gas mixture. The ch emical 
reaction of combustion of biogas (containing 60 % methane and 40 % carbon dioxide) and air mixture is 
shown below:    
0.6CH 4 + 0.4CO 2 + 1.2O2 + 4.5N2     CO 2  + 1.2H2O + 4.5N2 + Energy  
Thus, one volume of biogas requires 5.7 volumes of air or the s toichiometric requirement is 1/ (1+5.7) = 0.149, 
i.e., 14.9 per cent biogas in air.    
The biogas burns over a narrow range of mixtures from approximately 9 per cent to 17 percent of biogas in 
air. If the flame is ‘too rich’, i.e., has too much fuel, then it will burn badly and incompletely, giving carbon 
monoxide, which is poisonous and soot particles. Therefore, the designs of appliances should aim at to 
maximize the conversion of methane into carbon dioxide in order to minimize the release of unburned 
methane and products of incomplete combustion.   
The large quantity of carbon dioxide present in biogas poses a threat to stable combustion of biogas. CO2 
traps not only heat but it also interacts with the flame which could potentially cool the flame down en ough that 
it becomes unstable and blows out. Similarly, the water vapours present in biogas have a small but noticeable 
impact on flame temperature, inflammability limits, lower heating value and air -fuel ratio of biogas.  
B.2 Flame  
Biogas flame is cone sha ped and consists of an inner cone and an outer mantle as shown in Figure B.1. 
When biogas and air mixture reaches the burner ports and burnt with a pilot heat, it forms a cone shaped blue 
flame. The cone shape of the flame is a result of laminar flow in a cylindrical mixing tube. The unburned gas is 
heated up in an inner cone and starts burning at the flame front. The mixture at the centre of the tube moves 
at a higher velocity than at the outside. In the main combustion zone, gas burns in the primary air a nd 
generates heat in the flame and combustion is completed at the outer mantle of the flame with the aid of 
secondary air or the flame from the sides. With the vertical rise of combustion products, i.e., carbon dioxide 
and water vapours , heat is transferre d to the air close to the top of the flame. The hot air, which moves 
vertically away, draws in cooler secondary air to the base of the flame. The size of the inner cone depends on 
the primary aeration. A high proportion of primary air makes the flame much smaller and concentrated, giving 
higher flame temperature. If combustion is complete, which requires a temperature of less than 850oC and DUS 1643 : 2016  
© UNBS 2016  – All rights reserved  15 
 residence time of less than 0.3 second, the flame is dark blue and almost invisible in daylight. If too little air is 
available, then the gas does not burn fully and part of the gas escapes unused. With too much supply of air, 
the flame cools off and as a result the consumption of biogas is increased and the cooking time is prolonged. 
Further there is a risk of flame lift ing which can result in undesirable high CO concentration.  
 
  
16 © UNBS 2016  – All rights reserved  
 Bibliography  
[1]  
f DUS 1643 : 2016  
© UNBS 2016  – All rights reserved  17 
 Certification marking  
Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards (UNBS) Certification Mark 
shown in the figure below.  
The use of the UNBS Certification Mark is governed by the Standards Act, and the Regulations made thereunder. This mark can be  
used only by those licensed under the certification mark scheme operated by the Uganda National Bureau of Standards and in 
conjunc tion with the relevant Uganda Standard. The presence of this mark on a product or in relation to a product is an assurance th at 
the goods comply with the requirements of that standard under a system of supervision, control and testing in accordance with  the 
certification mark scheme of the Uganda National Bureau of Standards. UNBS marked products are continually checked by UNBS fo r 
conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda National Bureau of Sta ndards.  
 
 DUS 1643 : 2016    
 
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Price based on nn pages  
© UNBS 2016 – All rights reserved