DRAFT UGANDA STANDARD  
  DUS 971  
Second Edition  
2019-mm-dd  
 
 
 Reference number 
DUS 971: 201 9
© UNBS 2019  
  
Liquefied Petroleum Gases (LPG) —Product Specificat ions 
 DUS 971:2019 
© UNBS yyyy – All rights reserved  ii
 Compliance with this standard does not, of itself c onfer immunity from legal obligations 
A Uganda Standard does not purport to include all n ecessary provisions of a contract. Users are 
responsible for its correct application  
© UNBS 20019  
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permission from UNBS. 
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The Executive Director 
Uganda National Bureau of Standards 
P.O. Box 6329 
Kampala 
Uganda 
Tel: 256 414 505 995 
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 DUS 971:2019 
© UNBS yyyy – All rights reserved  iii
 Foreword 
Uganda National Bureau of Standards (UNBS) is a par astatal under the Ministry of Trade, Industry and 
Cooperatives established under Cap 327, of the Laws  of Uganda, as amended.  UNBS is mandated to co-
ordinate the elaboration of standards and is  
a) a member of International Organisation for Standard isation (ISO) and  
b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
c) the National Enquiry Point on TBT Agreement of the World Trade Organisation (WTO).  
The work of preparing Uganda Standards is carried o ut through Technical Committees. A Technical Commit tee 
is established to deliberate on standards in a give n field or area and consists of key stakeholders in cluding 
government, academia, consumer groups, private sect or and other interested parties.  
Draft Uganda Standards adopted by the Technical Com mittee are widely circulated to stakeholders and th e 
general public for comments. The committee reviews the comments before recommending the draft standard s 
for approval and declaration as Uganda Standards by  the National Standards Council.  
The committee responsible for this document is Tech nical Committee UNBS/TC 16, [Petroleum Products and  
Facilities], Subcommittee SC 1, [Petroleum and Petr ochemicals Products].  
This second edition cancels and replaces the first edition (US 971-4:2014), which has been technically  revised .  
 DUS 971:2019 
© UNBS yyyy – All rights reserved  iv
 Introduction 
Liquefied petroleum gas products are composed of th ose readily liquefiable hydrocarbon compounds that are 
produced in the course of processing natural gas an d also in the course of the conventional refining o f crude 
oil. The composition of liquefied gases can vary wi dely depending upon the source and the nature of th e 
treatment to which the products have been subjected . 
There are many uses for liquefied petroleum gases. Important uses include,  
a) as domestic, commercial, and industrial fuels,  
b) as a carbon source material in metal treating op erations,  
c) as refinery raw materials for synthesis of gasol ine components, and  
d) as petrochemical raw materials.  
In substance, this specification is designed to pro perly define acceptable products for domestic, comm ercial, 
and industrial uses. In many cases it will be found  that products meeting the specifications will also  be usable 
in applications other than the ones for which they were designed. The following can be accepted as a g eneral 
guide in the more common use applications of the th ree types of fuels:  
Commercial Propane—This fuel type is adequate for d omestic, commercial, and industrial use, particular ly in 
geographical areas and in seasons where low ambient  temperatures are common, and where uniformity of 
fuel is an important consideration. Commercial prop ane can be suitable for certain low severity intern al 
combustion engine applications.  
Commercial PB Mixtures—This fuel type, since it cov ers a broad range of mixtures, permits the tailorin g of 
fuels to specific needs. The various mixtures find application as domestic, commercial, and industrial  fuel in 
areas and at times when low ambient temperature con ditions are not encountered. This fuel type is not 
suitable for vapor withdrawal applications in cool or cold climates. 
Commercial Butane—This fuel type finds limited appl ication as a domestic fuel in areas of warmer clima tes. It 
is similarly used in industrial applications where problems of fuel vaporization are not present, such  as direct 
liquid injection. 
 
 DRAFT UGANDA STANDARD DUS 971: 2019
 
© UNBS 2018– All rights reserved  1
 Liquefied Petroleum Gases (LPG) — Specification 
1 Scope 
This draft Uganda standard prescribes the requireme nts and methods of sampling and test for those prod ucts 
commonly referred to as liquefied petroleum gases, consisting  of commercial propane, commercial butane, 
and commercial propane butane mixture 
This specification is applicable to products intend ed for use as domestic, commercial and industrial h eating  
HEALTH AND SAFETY WARNING -  The use of this draft Uganda Standard involves pote ntially hazardous 
materials, operations and equipment. This Standard does not purport to address all of the safety probl ems 
associated with its use. It is the responsibility o f the user to consult the relevant safety and healt h regulations, 
determine the applicability of regulatory limitatio ns, and establish appropriate safety and health pra ctices, prior 
to use.  
2 Normative references 
The following referenced documents are indispensabl e for the application of this document. For dated 
references, only the edition cited applies. For und ated references, the latest edition of the referenc ed document 
(including any amendments) applies. 
DUS ISO 3993, Liquefied petroleum gas and light hydrocarbons - De termination of density or relative density – 
Pressure hydrometer method  
DUS  ISO 4256, Liquefied petroleum gases – Determination of vapour  pressure - L PG method . 
DUS  ISO 4257, Liquefied petroleum gases - Method of sampling 
DUS  ISO 4259, Petroleum products - Determination and application of precision data in relation to methods of 
test 
DUS  ISO 4266, Petroleum products and hydrocarbons - Determination  of sulphur content - Wickbold combustion 
method 
DUS  ISO 6251, Liquefied petroleum gases – Corrosiveness to copper  - Copper strip test  
DUS  ISO 7941, Commercial propane and butane – Analysis by gas chr omatography  
DUS  ISO 8819 , Liquefied petroleum gases - Detection of hydrogen s ulphide - Lead acetate method 
DUS ISO 8973, Liquefied petroleum gases – Calculation method for density and vapour pressure  
DUS ISO 13758, Liquefied petroleum gases -- Assessment of the dryn ess of propane -- Valve freeze method 
DUS  ISO7225, Gas cylinders-Precautionary labels 
DUS  ISO 13758, Liquefied petroleum gases — Assessment of the dryness of propane — Valve freeze method 
DUS  ISO 13757, Liquefied petroleum gases — Determinati on of oily residues — High-temperature method 
DUS 2147:2019, Standard Test Method for Determination of Ethyl Mer captan in LP-Gas Vapour 
DUS 2148:2019, Standard test method for determination of total vol atile sulphur in gaseous hydrocarbons DUS  971: 2019  
© UNBS 2019 – All rights reserved  2
 and liquefied petroleum gases by ultraviolet fluore scence  
3 Terms and definitions 
For the purposes of this standard, the following te rms and definitions shall apply   
3.1   
LP Gases  
liquefied petroleum gases consisting of readily liq uefiable hydrocarbons predominantly of C 3 and C 4 
compounds that are intended primarily as fuel in do mestic, commercial, industrial heating and in spark  ignition 
internal combustion engines.  
3.2  
Commercial propane:  
hydrocarbon products composed predominantly of prop ane and/or propene (C 3) with a characteristic added 
stench; the remaining part may consist mainly of et hane/ethene and butane/butene isomers. It’s normall y 
used where high volatility is required   
3.3   
Commercial butane:  
hydrocarbon products composed predominantly of buta ne and/or butene (C 4) with a characteristic added 
stench; the remaining part may consist mainly of pr opane/propene and pentane/ pentene isomers.  It’s 
normally used where low volatility is required 
3.4   
Commercial PB mixture:  
mixtures of predominantly propane and butane (C 3 and C 4) with a characteristic stench added; for use where  
intermediate volatility is required. 
3.6   
defective  
a test sample of the liquefied petroleum gas that f ails in one or more respects to comply with the rel evant 
requirements of this standard. 
3.7 
Cross filling 
when one  operator fills another operator's cylinde r 
4 Requirements 
4.1 General 
4.1.1 LPG gas shall have a characteristic odour, an d an appearance that is clear, bright and free from  
suspended particles on visual inspection 
4.1.2  LPG gas described as commercial propane, sha ll be of an aliphatic hydrocarbon mixture that cons ists 
predominantly of C3 hydrocarbons, free from entrain ed moisture and complies with the appropriate 
requirements as specified in Table 1. 
4.1.3  LPG gas described as commercial butane shall  be of an aliphatic hydrocarbon mixture that consis ts 
predominantly of C4 hydrocarbons, free from entrain ed moisture and complies with the appropriate 
requirements as specified in Table 1. 
4.1.4 LPG gas described as commercial BP mixture sh all be aliphatic hydrocarbon mixture that consists 
predominantly of C3 and C4 hydrocarbons, free from entrained moisture and complies with the appropriat e 
requirements given in table 1 DUS  971: 2019  
© UNBS 2019 – All rights reserved  3
 . 
4.2 Specifications 
When determined in accordance with the methods give n in table 1, the properties of LPG gases shall con form 
to the requirements prescribed. 
Table 1 — Specifications for liquefied petroleum ga ses  
Characteristics  Commerci 
al propane Commercial 
butane Commercial 
BP mixture Test 
methods 
Vapours pressure (Gauge) at 40 °C, kPa, max. 1434 4 83 1430 A DUS ISO 
4256 
Volatility; 
Total acetylene content, mol% max 
 
Total dienes content, mol% max (including 1,3 
butadiene) 
 
Total C 4 and higher, mol% max 
 
C5 and higher hydrocarbons, mol% max   
2.0 
 
Nil 
 
 
2.5 
 
0  
2.0 
 
0.5 
 
 
Nil 
 
2.0  
2.0 
 
0.5 
 
 
Nil 
 
2.0  
 
DUS ISO 
7941 
Residues on evaporation of 100ml, max ml 0.05 0.05 0.05 DUS ISO 
13757 
Copper strip corrosion, max 1 1 1 DUS ISO 
6251 
Total Sulphur (after stenching), mg/kg max. 185 140  140 DUS 2148 
Hydrogen sulphide  Nil Nil Nil DUS ISO 
8819 
Moisture content (dryness)  Pass - - DUS ISO 
13758 
Free water content  - None None Visual 
Density at 15°C or relative density at 15.615°C B Should be 
reported Should be 
reported Should be 
reported DUS ISO 
3993 or 
ISO 8973. 
Odurization: ethyl mercaptan, µL/mL, min 15 15 15 D US 2147 
A The permissible vapour pressure of products classif ied as BP mixtures shall not exceed 1430 kPa and ad ditionally, shall not exceed 
that calculated from the following relationship bet ween the observed vapour pressure and observed rela tive density: 
Vapour pressure, max. = 1167- 1880 (relative densit y at 15/15.6 °C ) 
 
B Although not a specific requirement, the density o r relative density can be needed for other purposes  and should be reported. 
Additionally, the relative density of BP mixture is  needed to establish the permissible maximum vapour  pressure  (see Foot note A)  
 
Note   Individual contractual agreements, national safety  codes, regulations and/or requirements of 
distribution systems shall be complied with in addi tion to the specifications in table 1 . 
 DUS  971: 2019  
© UNBS 2019 – All rights reserved  4
 5 Precision and interpretation of tests results 
Most of the methods of test given in table 1 contai n a statement of the precision, i.e. the repeatabil ity and 
reproducibility, to be expected from them but, in c ases of dispute, the procedure described in DUS ISO  4259, 
which uses precision data in the interpretation of test results, shall prevail.  
6 Packing and Marking 
6.1 Packing 
The condition of cylinders and road tank vehicles s hall be such as not to be detrimental to the qualit y of the gas 
during normal transportation and storage. 
The containers shall be acceptably sealed or leak p roof, clean, and free from materials soluble in the  gas 
Note:  For safety purposes, all cylinders should not be c ross filled among the operators  
6.2 Marking  
The following information shall appear in legible a nd indelible marking on each cylinder and tank cont ainer,  or 
in the case of gas filled into bulk storage tanks, in the storage and consignment documents of each ro ad tanker 
or rail tank wagon: 
a) the supplier’s name or brand name or trade mark;  
b) Product name ― LPG ;  
c) the type of liquefied petroleum gas supplied, i. e. commercial propane, commercial butane or 
commercial propane butane mixture. 
d) the batch/lot number; 
e) net weight in Kilograms (kg); 
f) Precautionary labels that apply to safety and pr oper handling of LPG in accordance to DUS ISO 7225 
g) Expiry date 
7 Sampling  
7.1 Sampling 
Representative sample of non-refrigerated liquefied  petroleum gases shall be taken in accordance with the 
procedure given in ISO 4257. The sample so drawn sh all be deemed to represent the lot and shall be tes ted 
for the respective properties in table 1 to determi ne whether or not the lot complies with the require ments of 
this standard. 
For refrigerated liquefied petroleum gases a sampli ng procedure shall be agreed upon between the parti es 
concerned. 
Note  Proper sampling of the liquefied petroleum is  extremely important if the test results are to be significant. 
7.2 Lot 
The quantity of Liquefied Petroleum gases in contai ners and bearing the same brand name or trademark, 
grade designation and batch identification, from on e manufacturer, and submitted at any one time for 
inspection and testing shall constitute a lot. 
 DUS  971: 2019  
© UNBS 2019 – All rights reserved  5
 Annex A 
(informative)  
 
Significance of this specifications for liquefied p etroleum (LP) gases 
A.1 General 
This specification addresses commercial liquefied p etroleum gases consisting of either propane or buta ne or 
mixtures thereof. Consequently, the important chara cteristics of these products can be defined and con trolled 
by a relatively few simple measurements. The specif ication test methods provided achieve the desired r esults. 
The significance of the various tests as they can a pply to consumer problems is summarized here. 
A.2  Vapour Pressure, Volatility, and [Relative] Density : 
A.2.1  Vapour Pressure —indirect measure of the most extr eme low-temperature conditions under which 
initial vaporization can be expected to take place.  It can be considered as a semi-quantitative measur e of the 
amount of the most volatile material present in the  product. It can also be used as a means for predic ting the 
maximum pressures which can be experienced at fuel tank temperatures. Vapour pressure becomes more 
significant when it is related to volatility. 
A.2.2 Volatility —Expressed in terms of the 95 % evaporated temperat ure of the product, is a measure of 
the amount of least volatile fuel component present  in the product. Coupled with a vapour pressure lim it, it 
serves to assure essentially single-component produ cts in the cases of commercial propane and commerci al 
butane fuel types. When volatility is coupled with a vapour pressure limit which has been related to d ensity or 
gravity, as in the case of the commercial PB-mixtur e type of fuels, the combination serves to assure 
essentially two component mixtures for such fuels. When coupled with a proper vapour pressure limit, t his 
measurement serves to assure that special-duty prop ane products will be composed chiefly of propane an d 
propylene and that propane will be the major consti tuent. 
A.2.3 Density or Relative Density —by itself, has little significance. It becomes of value when related to 
vapour pressure and volatility. Since density or re lative density is of importance in meeting transpor tation and 
storage requirements it is always determined for al l liquefied petroleum gas products. 
A.3 Other Product Characteristics 
While the vaporization and combustion characteristi cs of commercial liquefied gas products are complet ely 
defined for the normal use applications by vapour p ressure, volatility, and relative density, as given  in A.2, 
there are other properties which either affect or m ight affect the results obtained in some specific u se 
applications. For that reason, limits are specified  for residue content, copper corrosion, sulphur con tent, 
moisture content, and free water content to provide  assurance of product dependability under the more 
extreme conditions of use. 
A.3.1 Residue —A measure of the concentration of soluble hydrocar bon materials present in the product 
which are substantially less volatile than the liqu efied petroleum gas product being sampled. Control of 
residue content is importance in applications where  the fuel is used in liquid or vapour feed systems (where 
fuel vapours are withdrawn from the top of the LPG storage container). In either case, failure to limi t the 
permissible concentration of residue materials can result in troublesome deposits or regulating equipm ent can 
become fouled, or both. In gas processing plants, L P gas generally is produced relatively free of resi dues, but 
the product can become contaminated by heavier hydr ocarbons and other organic compounds during 
distribution, especially in multiproduct pipelines or while it is in contact with elastomers used in h oses. The 
current limit on residue contamination, while gener ally satisfactory for many conventional uses, may n ot be 
suitable for newer applications such as fuel cells and micro-turbines without some form of remediation . 
A.3.2 Copper Corrosion  —Limits are for the purpose of providing assurance that difficulties will not be 
experienced in the deterioration of the copper and copper-alloy fittings and connections which are com monly 
used in many types of utilization, storage, and tra nsportation equipment. The copper corrosion test wi ll detect DUS  971: 2019  
© UNBS 2019 – All rights reserved  6
 the presence of elemental sulphur and hydrogen sulp hide, which is highly toxic. The copper corrosion l imits 
also provide assurance that the LP-Gas will not con tain H 2S in such quantities as to present a health and 
safety hazard if it is known that the product does not contain corrosion inhibitors or other chemicals  which 
diminish the reaction with the copper strip. In add ition, Test Method ISO 8819  is recommended as a field test 
and added safeguard to ensure that LP-Gas does not contain detectable amounts of hydrogen sulphide. 
A.3.3 Sulphur Content  —Limits are provided to more completely define liq uefied petroleum gas products. 
Historically these products were lower in sulphur c ontent than most other petroleum-derived fuels. Thi s is 
generally no longer the case in areas where gasolin es are typically below 30 mg/kg (ppm by mass) sulph ur 
and diesel fuels are less than 15 mg/kg (ppm by mas s) sulphur. The limit on sulphur content minimizes 
sulphur oxide emissions and limits potential corros ion by exhaust gases from combustion of LPG. 
A.3.4 Moisture Content —limits the percent saturation of the product with water. This measurement using 
Test Method ISO13758  is a requirement only on commercial propane type of  liquefied petroleum gas which 
must be subsaturated with water at temperatures abo ve about -26°C. The purpose of moisture content con trol 
is to provide assurance that pressure reducing regu lators and similar equipment will operate consisten tly 
without troublesome freeze-ups caused by the separa tion of dissolved water from the product. 
The presence of an antifreeze agent such as methyl alcohol which prevents separated water from freezin g 
can allow use of propane containing excessive disso lved water in many applications. 
Note Commercial propane and special duty propane sh ould be produced to comply with the moisture conten t requirement, and de-
icer additives should not routinely be used to pass  dryness test requirements . 
That is, these products must be so dry that they ar e subsaturated with water at most ambient temperatu res. 
They should be maintained dry during storage and di stribution. A de-icer such as methyl alcohol (metha nol) 
should not be added to these products without speci fic agreement and approval of the purchaser. During  
short-term upsets in production, or inadvertent con tamination by trace water during storage or distrib ution, 
addition of 50 ppm methyl alcohol has proven to be acceptable to prevent valve freezing in normal 
applications. For guidance, based on historical exp erience and phase separation data, the maximum 
cumulative addition of methyl alcohol should not ex ceed 200 ppm by volume. 
A.3.5 Free Water Content —of importance only on the commercial PB-mixtures a nd commercial butane type 
products. These two types of products are normally used under ambient conditions which are mild and, a s a 
consequence, the only requirement is vigilance to e nsure that no free water is present. 
 DUS  971: 2019  
© UNBS 2019 – All rights reserved  7
 Bibliography 
[1] ISO 9162: 1989, Petroleum products – Fuels (Class F) – Liquefied pe troleum gases - Specifications  
[2] ISO 8216-3: 1987, Petroleum products - Fuels (c lass F) - Classification - Part 3: Family L (Liquef ied 
petroleum gases) 
[3] ASTM D1835 – 11, Standard specifications for liquefied petroleum (LP ) Gases  
[4] ISO 9162:2013 Petroleum products — Fuels (class  F) — Liquefied petroleum gases — Specifications 
[5] SANS 1774, Liquefied petroleum gases 
  
. DUS  971: 2019  
© UNBS 2018– All rights reserved  9
 Certification marking 
Products that conform to Uganda standards may be ma rked 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 lic ensed under the certification mark scheme operated by the 
Uganda National Bureau of Standards and in conjunct ion with the relevant Uganda Standard. The presence  of 
this mark on a product or in relation to a product is an assurance that the goods comply with the requ irements 
of that standard under a system of supervision, con trol and testing in accordance with the certificati on mark 
scheme of the Uganda National Bureau of Standards. UNBS marked products are continually checked by UNB S 
for conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda  National 
Bureau of Standards.  
 
 
DUS 971 : 2019 
 
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