ICS  97.040.20  
 
Reference number  
DRS 461: 2021  
© RSB 2021  
  
 RWANDA 
STANDARD  DRS  
461  
 
1st edition  
2021-02-xx 
 
domestic gas stoves for use with  liquefied 
petroleum gases —requirements  
   
DRS 461: 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 R SB. 
Requests for permission to reprodu ce 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.rs b.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 461: 2021  
iii                ©RSB 2021  - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ...................  iv 
1 Scope  ................................ ................................ ................................ ................................ .............  1 
2 Normative references  ................................ ................................ ................................ ...................  1 
3 Terms and definitions  ................................ ................................ ................................ ..................  1 
4 Requirements  ................................ ................................ ................................ ................................  2 
4.1 General  ................................ ................................ ................................ ................................ ..........  2 
4.2 Material  ................................ ................................ ................................ ................................ ..........  2 
4.3 Gas taps  ................................ ................................ ................................ ................................ ........  2 
4.4 Injector jets  ................................ ................................ ................................ ................................ ... 3 
4.5 Burners  ................................ ................................ ................................ ................................ ..........  4 
4.6 Burner pan supports  ................................ ................................ ................................ ....................  4 
4.7 Gas inlet connections  ................................ ................................ ................................ ..................  5 
5 Test methods  ................................ ................................ ................................ ................................  5 
5.1 General conditio ns of test  ................................ ................................ ................................ ...........  5 
5.2 Gas consumption  ................................ ................................ ................................ .........................  6 
6 Strength and rigidity  ................................ ................................ ................................ ....................  6 
7 Flame st ability  ................................ ................................ ................................ ...............................  6 
8 Noise control  ................................ ................................ ................................ ................................ . 7 
9 Flash back  ................................ ................................ ................................ ................................ ..... 7 
10 Formation of soot  ................................ ................................ ................................ .........................  7 
11 Resistance to draught  ................................ ................................ ................................ ..................  7 
12 Combustion  ................................ ................................ ................................ ................................ ... 8 
13 Thermal efficiency  ................................ ................................ ................................ ........................  8 
14 Workmanship and finish  ................................ ................................ ................................ ..............  8 
15 Marki ng ................................ ................................ ................................ ................................ ..........  9 
Annex  A (normative)  Strength and rigidity test ................................ ................................ ...................  10 
A.1 Procedure  ................................ ................................ .........................  Error! Bookmark not defined.  
Annex  B (normative)  Gas consumption test  ................................ ................................ .......................  11 
B.1 Procedure  ................................ ................................ .........................  Error! Bookmark not defined.  
Annex  C (normative)  determination of carbon monoxide/carbon dioxide ratio  ..............................  12 
Annex  D (normative)  thermal efficiency Test  ................................ ................................ ......................  14 
 DRS 461: 2021  
©RSB 2021  - All rights reserved                  iv 
 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 adopted 
by Technical committ ees are ratifie d by me mbers of RSB Board of Director s for publication and gazettment as 
Rwanda Standards.  
DRS  461 was prepared by Technical Committee RSB/TC 026, LPG and Natural gas equipment and accessories  
In the preparation of this standard, reference was made to the following standard:  
1) IS 4246 (2002): Domestic Gas Stoves for use with Liquefied Petroleum Gases  
The assistance de rived from the above source is hereby acknowledged with thanks.  
Committee membership  
The following organizations were represented on the Technical Committee on LPG and Natural gas equipment 
and accessories  (RSB/TC 026) in the preparation of this standard.  
 
SAFE GAS  
Ministry of Infrastructure  (MININFRA)  
Energy Development Corporate Limited   
Rwanda Mines Board  
University of Rwanda / College of Science and Technology  
SULFO Ltd  
Rwanda Utility Regulatory Authority  
Societe Petroliere  
MOTA ENGIL  
ALMAHA Group ltd  
HASHI Energy  DRS 461: 2021  
©RSB 2021  - All rights reserved                  ii 
 Rwanda  Standards Board  (RSB) – Secretariat  
 DRS 461: 2021  
1                ©RSB 2021  - All rights reserved  
 Domestic  gas stoves for use with liquefied petroleum gases — 
requirements  
1 Scope   
This draft standard provides requirement for construction , operation, safety and tests  methods for domestic gas 
stoves with metallic bodies intended for use with liquefied petroleum gases at 3000  kN/m2 (30 gf/cm2) gas inlet 
pressure.  
2 Normative references   
The following documents are referred to in the text in su ch a way that some or all of  their content constitutes 
requirements 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.  
3 Terms and definitions   
For the purposes of this standard, the follow ing terms and definitions apply  
3.1 
Burner  
device for the final conveyance of the gas or a mixture of gas and air to produce a suitable flame which is 
maintained on or in it.  
3.2 
Flame Failure Dev ice (Flame  Safeguard)   
A control responsive to flame properties, detecting the presence of a nominated flame and, in the event of 
ignition failure or subsequent flame failure, causing safety shut down.  
3.3  
Grill (Griller)   
An appliance for cooking food by  means of radiant heat.  
3.4 
Gas Injector (Injector  Jet)  
A jet removable and/or adjustable by means of which a calibrated amount of gas is allowed to pass through an 
orifice.   
©RSB 2021  - All rights reserved                  2 
 3.5  
Knob  
A gripping component attached to a control (gas tap, thermostat, etc.) for manually rotating it.  
4 Requirements  
4.1 General  
4.1.1 The appliance, including all the component parts, shall be easy to clean and maintain in good working 
order, t here shall be easy access to the accessories and controls for maintenance and adjustment.  
4.1.2 Parts, which are intended to be removable by the user, shall be easy to replace correctly, and difficult to 
assemble incorrectly.  
4.1.3 All nuts, bolts and fittings shall be easily  accessible  to appropriate tools . 
4.1.4 The appliance shall be so designed that it remains stable and shall not be easily overturned.  
4.2 Material  
4.2.1  The material used in the construction of gas cooker components shall be  made of non -corrosive material 
or appropriately treated to resist corrosion.  
4.2.2  The main body of t he burner (including mixer head, mixing tube and burner head) shall be of substantial 
and durable construction , metals having a melting point below 510°C shall not be considered acceptable for top 
burners . 
4.2.3  The burner parts shall not melt or distort when the stove burner is operated with flames flashed back for 
half an hour in the mixing tube.  
4.2.4  Plastic components which are liable to  heating (for example, tap handles, push  buttons, etc) shall be free 
of fissures, distortion,  blemishes and discoloration   
 
4.3 Gas taps  
4.3.1 The appliance shall have at least one tap for each burner.  
4.3.2 The 'ON', 'OFF' and any fixed position of tap handles shall be clearly and durably indicated or shall b e 
obvious by design or position.  Each gas tap shall indicate on its knob the burners it operates . All taps shall close 
in the same direction. The direction of rotation of a tap knob (handle) from off -on-simmer shall be anti -clockwise. 
Taps shall be designed so that when place d in any position and viewed from a distance of 3 m, will definitely 
indicate whether the valve is open or closed or in intermediate position.  
4.3.3 Where taps are fitted with adjustable stops, there shall be means for locking the stops in position. If scr ews 
are used for this purpose, they shall not lead into gas passages.  DRS 461: 2021  
3                ©RSB 2021  - All rights reserved  
 4.3.4 Preferably all taps (excluding pilot taps) should lock in the 'OFF' position but in all cases it shall be 
impossible for any handle or tap to move accidentally, for example, by the  weight of plugs or handles or when 
caught by clothing. If this requirement is satisfied by means of an automatic locking device, the tap shall be 
easy to operate with one hand.  
4.3.5 Taps shall be so made that in normal use and with reasonable application  of lubricant, the gas passages 
do not become blocked.  
4.3.6 Taps shall be lubricated with a suitable grease, resistant to the action of the gas and capable of operating 
at the maximum temperature of 110°C.  
4.3.7 Each taper plug tap shall be spring -loaded to maintain a gas -tight fit. Helical springs fitted in taps and 
valves shall have flattened ends, which shall be rounded before fitting.  
4.3.8 All controls or taps shall be easy to operate at all temperatures normally attained in use.  
4.3.9 Screws, nuts, e tc, which regulate the tension of taps valve or springs, shall not loosen in operation of the 
appliance. It shall not be possible to cause a leak during normal manual operation of tap.  
4.3.10 Screw -down valves shall be so designed that it is impossible to withdraw completely the valve stem in 
the normal operation of the tap.  
4.3.11 Taps having an 'OFF' position shall have positive stops at the 'OFF' and simmer position except that 
special purpose taps (for appliance incorporating auto or self-ignition  device), for example, taps with simmering 
position in between 'OFF' and 'ON' may have a movement  beyond the simmer position with a positive stop.  
4.3.12 Simmer flame shall be obtained by fixed simmer orifice.  
4.3.13 the niting means adopted shall be suffi ciently robust to withstand normal use without distortion or 
damage.   
4.4 Injector jets  
4.4.1 The injector Jets shall be fixed calibrated type and it shall not be possible to loosen them without the use 
of tools. The dimensions of the injector Jet shall conform to the following requirements:  
 
S/N Items  dimensions  
1 Across flats  6 mm, Min  
 
2 Projection from the face of mounting  6 mm. nominal  
 
3 Threads  M 5 or 1BA  
 
 
  
©RSB 2021  - All rights reserved                  4 
 4.4.2  Injector Jet shall be made of metal, with or without ceramic tip. The melting point of the metal shall not be 
less than 650°C.  
4.4.3 The size of the Jet in liters  per hour of flow of LPG at STP conditions shall be impressed upon it.  
4.5 Burners  
4.5.1  The construction of the burners and the assembly shall allow their dismantling from the supports easily 
with or without the use of tools  
4.5.2 The burner supports shall be  rigid and shall be fixed in their place. Their construction shall ensure the 
stability of the burners and shall prevent their undue movement in a horizontal plane.  
4.5.3 The lightness of the joints in the burner assembly shall not depend upon adhesives or  any kind of packin g. 
4.5.4  For burners having centre flame, provision shall be made to protect the centre flame from pans resting 
directly on burner top and smothering the centre flame.  
4.5.5  The appliance comprising two or more burners shall include one burner having a rating of at least 1 490 
kcal/h, based on net calorific value of the gas (when using commercial LPG).  
 
 
4.5.6 The parts of the burner shall not become disconnected during opera tion of the appliance. The burners 
should be so spaced that the relative distance between the centers of the adjoining burner shall not be less than 
180 mm.  
4.5.7 Burner ports shall be so designed and located that in normal use spillage of food shall not c ause internal 
fouling of mixing tube and/or blockage of injector jet.  
4.5.8 Only the same rating model and make of burners and parts of burners, shall be interchangeable or 
replaceable without effecting performance.  
 
 
4.6 Burner pan supports  
4.6.1   The design of the pan supports shall be such that it is practicable to support a pan of 100mm diameter, 
over at least one top burner without the use of loose rings, and such that 125 mm diameter vessel remains 
stable over each burner. Prongs of the suppor t shall have suitable taper to accommodate round bottom pans.  
4.6.2 Loose pan supports shall be so designed that it is not possible to place them firmly in other than proper 
position.  DRS 461: 2021  
5                ©RSB 2021  - All rights reserved  
 4.7 Gas inlet connections  
4.7.1 Nozzles shall be machined from free cutting  brass or mild steel.  
4.7.2 Where nozzles for flexible tubing are fitted, they shall be so positioned as to facilitate fitting of the tubing 
and also to prevent heating  of the tubing to more than 60°C.  
4.7.3  The pipe/tube used for main gas rail shall be of mild steel . The wall thickness of main gas rail shall be 1.6 
mm + no Limit  /–0.15 mm. The external surface of the gas rail shall be treated to resist corrosion. Any other 
connection made from the main gas rail shall be only metallic.  
4.7.4  The position of the gas inlet shall allow connection to a gas supply on either side of the appliance. Inlet 
connection at the rear is also permitted. It shall be possible to change gas inlet from one side to other side easily 
by standard tools.  
 
5 Test methods  
5.1 General conditions of test  
5.1.1  During the tests the initial adjustment of appliance shall not be altered unless specifically required in the 
test procedure.  
5.1.2  The appliance shall be adjusted and operated in accordance with the instructions given on or issue d with 
the appliance.  
5.1.3 Before any tests are made the appliance shall be operated at its full working temperature for a sufficient 
period to remove any temporary protective coating, which might interfere with observations.  
5.1.4 The gas connections a nd system up to and including the burners shall be examined for leaks before and 
after test. The performance test results shall not be valid unless the system is sound.  
5.1.5 The appliance shall be at room temperature at the start of each test unless othe rwise stated.  
5.1.6 The room in which tests are conducted shall be adequately ventilated but free from perceptible draughts.  
5.1.7 The gas/air shall be supplied to the appliance through a control valve, an adjustable pressure regulator 
and an accurate met er with a pressure gauge on its inlet.  
5.1.8 A pressure gauge shall be fitted to the inlet of the appliance and additional water manometer to any 
pressure test points on the appliance.  
5.1.9 The gas/air pressure shall be measured correct to 2.5 mm water gauge at the inlet to the appliance and 
controlled so that any variation does not exceed 2.5 mm water gauge.  
5.1.10 except  where otherwise stated, the appliance shall satisfy the performance requirements using LPG.   
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5.1.11 wherever  the combustion characteristics of burners are concerned, each burner shall be tested 
separately and in all possible combinations with other burners. This procedure shall be used for appliance with 
up to four burners.  
 
5.1.12 For appliance with larger number o f burners, the test procedure becomes impossibly long and discretion 
shall be exercised to eliminate tests  on combinations of widely separated and which are fitted in appliance of 
open construction are unlikely to interfere with the combustion of each othe r. 
 
 
5.2 Gas consumption  
When tested for gas consumption, the apparatus shall be setup as given in Annex B.   
 
a) Each burner assembly under separate ‘ON/OFF’ control shall give  + 8 percent of the manufacturers’ 
specified gas consumpt ion in I/h or heat input in kcal/h at 2942 kN/m2 (30 gf/cm2) gas inlet pressure when 
measured by volumetric method with a wet gas meter using co mpressed air (27°C and 760 mm of mercury). 
Thereaft er using 0.75 as multiplying factor,  the value of airflow at STP so obtained to be conver ted to flow 
of LPG at STP.  
NOTE   for this test, one  Iitre of  LPG = 2.46  g. 
b) Multi burner appliances (namely, appliances  having more than one burner) shall give within + 5  and –15 
percent of the declared total gas consumption  in g/h or heat input in kcal/h at 2 942 kN/m2  (30 gf/cm2) gas 
inlet pressure with commercial LPG  and with all the taps turned on.  
 
NOTE  The measurement of volume shall be made with a wet gas flow meter and with minimum consumption 
of 6 Iitres or volume displacement of two revolutions of  the drum whichever is higher.  
 
6 Strength and rigidity  
 
When tested as specified in Annex A,  
a) the vertical resultant deflection of the top surface measured at the center  of length of the body, shall not 
exceed 2 mm and  
b) the distance between the opposite sides (lengthwise and widthwise) shall not change by more  than 5 mm 
combustion of each other.  
 
7 Flame stability  
 
7.1 It shall be possible to operate the appliance with taps fully open at gas inlet pressure from 2452 kN/m2 to 3432 kN/m2 
(25 gf/cm2 to 35 gf/cm2) without the flame extinguishing, blowing off or striking back and without the formation of soot.  
 DRS 461: 2021  
7                ©RSB 2021  - All rights reserved  
 7.2 When  the gas consumption of a burner is reduced to simmer after operating for half an hour at full ‘ON’, the flame shall 
not extinguish, bl ow off, strike back or form soot when tested with commercial LPG at 2942 kN/m2 (30 gf/cm2) gas inlet 
pressure.  
 
7.3 Pilot flames shall be stable, without lifting or soot deposition, at gas inlet pressure from 2 452kN/m2  to 3432 kN/m2 (25 
gf/cm2 to 35 gf/ cm2). 
 
7.4 The fixed minimum pilot rate shall be sufficient to relight the main burner  at 2452 kN/m2 (25 gf/cm2) gas inlet pressure.  
 
8 Noise control  
 
The ignition of the burner flames, their operation and turning ‘OFF’ shall not give rise to undue or excessive noise during 
all the operations.  
 
9 Flash back  
 
9.1 A vessel having diameter suitable to cover the pan supports duly filled with water, shall be placed on the burner under 
test.  
 
9.2 The tap of the burner shall be turned ‘ON’ and gas shall be allowed to flow through the burner at full rate, with taps 
fully opened and gas lighted.  
 
9.3 After half an hour, the flame shall be immediately reduced to simmer and then brought back to full si ze. The operation 
shall be repeated five times.  
 
9.4 No flash back shall occur during the test.  
 
NOTE  This applies for all pressures from 2452 kN/m2 to 3432 kN/m2 (25 gf/cm2 to 35 gf/cm2),  
 
 
10 Formation of soot  
 
10.1 A vessel, 150 mm diameter, full of water, shall be placed on the burner and the burner lighted at ‘ON’ position of the 
tap for one hour.  
 
10.2 After the test, no soot (unburned carbon) shall be deposited on the burner and on the bottom of the vessel.  
 
NOTE   This applies for all pressures from 2452 kN/m2 to 3432 kNlm2 (25 gf/cm2 to 35 gf/cm2).  
 
11 Resistance to draught  
 
11.1 There shall be no extinction of the flames on any of the burners operating at maximum consumption when the 
appliance is placed in a general (not localized) current of air with a velocity of 2 m/s, as measured with a rotating vane 
anemometer.  
 
11.2 The loc ation of the appliance relative to neighboring walls and the direction of the draught shall be varied to 
correspond to likely conditions of appliance installation.  
 
NOTE  This applies for all pressures from 2452 kN/m2 to 3432 kN/m2 (25 gf/cm2 to 35 gf/cm2 ). 
  
©RSB 2021  - All rights reserved                  8 
  
 
12 Combustion  
12.1 When tested according to the method laid down in Annex C, on no account the carbon monoxide carbon 
dioxide ratio of the exhaust gases of any burner. Operating  at any consumption at which the burner is stable at 
gas inlet pressure from 2452 kN/m2 to 3432 kN/m2 (25 gf/cm2 to 35 gf/cm2), exceed 0.02.  
12.2 It shall also be possible to obtain the required carbon  monoxide/carbon dioxide ratio with the pan supports 
reversed or put in any other possible position or with a large skirted vessel pIaced over any burner.  
NOTE  This test need not be performed on burners with a gas rate of less than 20 I/h at 2942 kN/m2 ( 30 gf /cm2) 
gas inlet pressure.  
12.3 The carbon dioxide and carbon monoxide content of the products of combust ion shall be determined by 
the methods capable of giving accuracy of 0.5 percent and 0.001 percent, respectively, of the volume of the 
sample.  
 
 
13 Thermal efficiency  
 
When tested as specified in Annex D , 
a)  The thermal efficiency shall be at least 64 percent for each burner with the pan support correctly on the 
pan supports.  
b) For this test, the net calorific value of the gas shall be employed. Thermal efficiency may be declared, if it 
is 68 percent and above.  
14 Workmanship and finish  
14.1 The finish of exposed parts shall be durable, easy to clean and not subject to excessive deterioration in 
normal use.  
14.2 Parts which come in contact with foodstuffs shall be capable of being hygienically cleaned.  
14.3 The finish shall, on visual examination, show no defects, such as pinholes, blisters, roughness and exposed 
areas of metal, which might give rise to unduly rapid deterioration in the use.  
14.4 The surface shall also be free from burrs and sharp edges, wh ich might cause injury to the user with normal 
operation.  
14.5 The external finished surfaces shall be easily cleanable.  DRS 461: 2021  
9                ©RSB 2021  - All rights reserved  
 14.6 Except for burners, all other parts, namely, springs, screws, bolts and nuts, pipes, pins, etc, which are 
visible can be removed for maintenance shall be of corrosion resistant material or treated to resist corrosion 
appropriate to the conditions of use.  
15 Marking  
Each appliance shall be legibly and indelibly marked with the following:  
a) Manufacturer’s name and/or initials or registered  trade -mark;  
b) Batch number and serial number  
c) Total gas consumption in g/h (with commercial LPG);  
d) Rating of the burners in kcal/h (with commercial LPG);  
e) The words ‘For use with commercial LPG at 2500 - 3500  kN/m2  
f) Country of origin; and  
g) Thermal efficiency.   
©RSB 2021  - All rights reserved                  10 
 Annex  A 
(normative)  
 
Strength and rigidity test  
A.1.1  The rubber support (grommet) if any, shall be removed and replaced with identical metal supports. The 
pan support and burner shall be removed and the distance between the sides of the appliance body being test ed 
shall be measured. A reference reading at the top surface of the body at the centre of the width shall be taken.  
A.1.2 A load of 250 N (25 kg) per burner shall be applied at the top surface subject to a minimum load of 500 N 
(50 kg) for a  single burner stove.  
A.1.3 The load shall be applied without impact to a strip of steel having 20 mm thickness, 100 mm width and as 
long as the width of the appliance (see Fig. 1).  
A.1.1  This strip shall be placed in the centre of the top surface of the appliance and its  length parallel to the 
front. The load shall be maintained for five minutes after which the  measurement for deflection at top surface of 
body (at  the centre of the width just in front of the strip) shall  be taken with the load in position . 
 
 
 
 
 
 
 
DRS 461: 2021  
11                ©RSB 2021  - All rights reserved  
 Annex  B 
(normative)  
 
Gas consumption test  
B.1 the stove shall be set in accordance with 16 with the addition of a suitable device for measuring gas 
consumption . The wet gas meter which is instrument commonly used for this purpose shall be set up in series 
with stove under test (see Fig. 2).  
B.2 Clean and dry air shall be passed at 2942 kN/m2 (30  gf/cm2) inlet pressure through  the stove for a few 
minutes to purge the system of air and to establish the gas pressure required Only one burner of the appli ance 
shall be tested at a time and during the test all gas delivered to the stove shall flow through the jet of the burner 
being tested  
B.3 Temperature of the room during the test shall  be betw een 25°C and 30”C.  
 
 
 
 
 
 
 
 
 
 
 
©RSB 2021  - All rights reserved                  12 
 Annex  C 
(normative)  
 
determination of carbon monoxide/carbon dioxide ratio  
C.1 The appliance shall be set -up in accordance with 16 in  addition, before  starting the test, a pan of 190 mm 
Diameter  and of suitable height and containing water sufficient for the test shall be placed over the burner . In 
addition, a collecting hood (see Fig. 3) suitable for  the burners under examination shall be obtained  
C.2 The hood shall be so designed that, while not interfering in any way with the normal combustion of the 
burner, it collects a fairly high proporti on of the products of combustion. Also, it shall be such that the sample 
collected represents the whole of the combustion gases and not those from any particular point.  
C.3 When using this hood, the damper provided shall be set or additional flue pipe adde d, so that spillage of 
the flue gases around the skirt is just prevented. With the sample hood in position over the burner under 
investigation, gas at inlet pressure of 2 452 kN/m2 (25 gf/cm2) shall be admitted and the burner operated for a 
few minutes bef ore sampling commenced. The reason for this being that during the fkst few minutes the burner 
is warming up and the proportion of carbon monoxide may be high. However, this is not dangerous provided 
the burner works satisfactorily after heating up.  
C.4 Any of the recognized methods having the prescribed accuracy may be used for gas analysis. For carbon 
monoxide, it is recommended that co -indicator of prescribed accuracy or iodine pentoxide method or catalytic 
method, for example, Drager method, the Katz met hod or infra red analysis methods may be used. Carbon 
dioxide may be tested with an Orsat apparatus, the Haldane apparatus or by infra red analysis.  
C.5 Each burner shall be examined with gas at 2452 kN/m2to 3432 kN/m2 (25 gf/cm2 to 35 gf/cm2) inlet 
pressure. It shall also be noted that each burner is tested separately or with all the possible combination of the 
other burners operating.  DRS 461: 2021  
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©RSB 2021  - All rights reserved                  14 
 Annex  D 
(normative)  
 
thermal efficiency Test   
D.1 The test shall be carried out by weighing the gas used. The gas shall be taken from a small bottle containing 
LPG weighing 1 kg to 2 kg. The bottle shall be fitted with an ‘On/Off’ valve and shall be connected to a regulator 
which, in turn, shall be connected  to a pressure gauge and to the appliance, a second ‘on/Off’ gas valve shall 
be inserted in the gas ways upstream of the regulator as near as possible to the gas bottle. A typical layout of 
set-up necessary for this test is shown in Fig. 4.  
D.2 The gas sha ll be passed at 2942 kN/m2 (30 gf/ cm2) inlet pressure through the stove for a few minutes to 
purge the system of air and to establish the gas pressure required. Only one burner of the appliance shalI be 
tested at a time and during the test all gas delivere d to the stove shall flow through the jet of the burner being 
tested. The pan shall be selected and loaded in accordance with the requirements given in Table 1 and placed 
centrally over the burner being tested.  The temperature of the water Tt  contained sha ll be noted and recorded 
as long as it remains constant.  
D.3 The bottle shall be disconnected, weighed. Reconnected and valves (1) and (2) opened. The gas control 
tap shall then be opened and the gas shall be ignited. The water shall be allowed to warm up to about 80 ‘C 
when stirring is commenced and continued until the end of the test. The burner shall be put off when the 
temperature of water reaches 90 ‘C + 1“C. The stirring shall be continued and the maximum temperature t 2 
shall be noted.  
D.4 Next, the v alves on the bottle and the gas line shall be  closed and the bottle shall be disconnected and 
reweighed.  It is thus possible to estimate the mass of  gas used during the period taken for the water to heat  up. 
Thermal efficiency shall be calculated by the  following formula:  
  
E = thermal efficiency of the burner in percent,  
G= quantity of water in the vessel in kg,  
W= water equivalent of the vessel complete with stirrer and lid  
T2 = final temperature of water in ‘C,  
T1 = initial temperature of water in “C,  
M= gas consumption in kg,  
K= calorific value of the gas in kcal/lcg.  
DRS 461: 2021  
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Gas rate at STP  
l/h Pan diameter 
(external)  
mm ±5  Pan height 
(external)  
mm Total pan mass with 
lid 
g±10%  Mas of water in pan  
Kg 
up to 40  180 100 356 2.0 
41-50 205 110 451 2.8 
51-60 220 120 519 3.7 
61-70 245 130 632 4.8 
71-80 260 140 750 6.1 
81-95 285 155 853 7.7 
96-107 295 165 920 9.4 
1 Distilled water (RS EAS 123 ) shall be used for test.  
2 The pan shall be cylindrical with flat bottom.  
3 The finish of the pan bottom from inside  shall always be bright.  
4 Above 107 I/h, pans shall be specially constructed to conform,  
as far as possible, with the principles used in formulating this table. 
 
D.5 In performing the thermal  efficiency test, the following points shall be noted:  
a) The set-up shall be carefully checked for leak, before and after the test. If a leak is found after the tests, the 
results should be cancelled and the test repeated.  
b) The room shall be free from draught.  
c) The initial temperature of the room shall be  between 25 “ C and 30 ‘C. The water  temperature shall be within 
± 2 “C of the  actual room temperature.  
d) The net c alorific value of gas is used. If this is  not determined experimentally, the value may  be taken a s 
10900 kcal/kg for calculation.  
e) At the start of the test, the burner shall be at room temperature.  
f) The temperature of the water shall be  measured by means of a mercury -in-glass  thermometer of accuracy 
of 0.5 C the bulb of  which is immersed to half the depth of the  water in vessel.  
g) Stirring shall be effected by me ans of a  horizontal loop of 3 mm metal rod attached  to an upright, which 
passes through a 6 mm,  hole drilled in lid.  
h) This test need not be performed on burners  with a gas rate of less  than 20 l/h  at 2942 kN/m2  (30 gf/cm2) 
inlet pressure.  
i) Accuracy of weighi ng balance used shall be  of 0.1 g for consumption measurement and  1 g for the other 
weights  
j) Specific heat of alumn ium is 0.214.   
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 k) For conducting thermal efficiency test, gas  from the commercial cylinder (bottle) of LPG,  the first two -thirds 
of which has been  allowed  to evaporate (to waste or in vapor withdrawal  use), the remaining one -third shall 
be used  for test. The use of last 1 or 2 kg of gas shall  be avoided as this may contain heavy ends.  
 
 
 
 
 
 
DRS 461: 2021  
 
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