DRAFT UGANDA STANDARD DRAFT UGANDA STANDARD  
  DUS 971-4 
First Edition  
2014 -02-13 
 
 
 Reference number  
DUS 971-4: 2011 
© UNBS 2014   
  
Liquefied Petroleum Gases (LP G) — Part 4 : Product 
Specifications 
 DRAFT UGANDA STANDARDDUS 971-4 : 2014  
ii © UNBS 2014  – 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 application  
© UNBS 2007  
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permission from UNBS. 
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Uganda National Bureau of Standards 
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Kampala 
Uganda 
Tel: 256 414 505 995 
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Web: www.unbs.go.ug  
 DRAFT UGANDA STANDARDDUS 971-4: 2014  
© UNBS 2014 – All rights reserved  iii 
 Foreword 
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Tourism, Trade and 
Industry 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 
Committee is established to deliberate on standards in a given field or area and consists of representatives of 
consumers, traders, academicians, manufacturers, 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 DRAFT UGANDA STANDARDDUS 971-4 : 2014  
iv © UNBS 2014  – All rights reserved  
 Introduction 
Liquefied petroleum gas products are composed of those readily liquefiable hydrocarbon compounds that are 
produced in the course of processing natural gas and also in the course of the conventional refining of crude 
oil. The composition of liquefied gases can vary widely depending upon the source and the nature of the 
treatment to which the products have been subjected. 
This specification addresses commercial liquefied petroleum gases consisting of either propane or butane or 
mixtures thereof.  There are many uses for liquefied petroleum gases. Important uses include, (1) as domestic, 
commercial, and industrial fuels, (2) as a carbon source material in metal treating operations, (3) as refinery 
raw materials for synthesis of gasoline components, and (4) as petrochemical raw materials. The nature of the 
use dictates the required composition characteristics in these various applications. Since the last three uses of 
those listed are in the category of specialty applications which involve special requirements, they are excluded 
from consideration in this specification.  
In substance, this specification is designed to properly define acceptable products for domestic, commercial, 
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 general 
guide in the more common use applications of the four types of fuels: 
Commercial Propane —This fuel type is adequate for domestic, commercial, and industrial use, particularly in 
geographical areas and in seasons where low ambient temperatures are common, and where uniformity of 
fuel is an important consideration. Commercial propane can be suitable for certain low severity internal 
combustion engine applications. 
Commercial Butane —This fuel type finds limited application as a domestic fuel in areas of warmer climates. It 
is similarly used in industrial applications where problems of fuel vaporization are not present, such as direct 
liquid injection. 
Commercial PB Mixtures —This fuel type, since it covers a broad range of mixtures, permits the tailoring 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 conditions are not encountered. This fuel type is not 
suitable for vapour withdrawal applications in cool or cold climates. 
 
 DRAFT UGANDA STANDARDDRAFT UGANDA STANDARD  DUS 971-4: 2014  
 
© UNBS 2011 – All rights reserved  1 
 Liquefied Petroleum Gases (LP G) — Part 4 : Specification 
1 Scope 
This draft Uganda standard specifies the requirements and methods of sampling and test for those products 
commonly referred to as liquefied petroleum gases, consisting; 
a) Predominantly of C3 hydrocarbons (propane/propene); 
b) Predominantly of C 4 hydrocarbons (butane/butene) and; 
c) Mixtures of C 3 and C 4 hydrocarbons  
This specification is applicable to products intended for use as domestic, c ommercial and industrial heating 
and engine fuels. 
HEALTH AND SAFETY WARNING -  The use of this Uganda Standard involves potentially hazardous 
materials, operations and equipment. This Standard does not purport to address all of the safety problems 
associated with its use. It is the responsibility of the user to consult the relevant safety and health regulations 
and material safety data sheets (MSDS), to determine the applicability of regulatory limitations, and establish 
appropriate safety and health practices, prior to use.  
2 Normative references 
The following referenced documents are indispensable for the application of this document. For dated 
references, only the edition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies. 
ISO 3993: 1984, Liquefied petroleum gas and light hydrocarbons - Determination of density or relative density 
– Pressure hydrometer method  
ISO 4256: 1978, Liquefied petroleum gases – Determination of vapour pressure - L PG method . 
ISO 4257: 1988, Liquefied petroleum gases - Method of sampling 
ISO 4259: 1979, Petroleum products - Determination and application of precision data in relation to methods of 
test 
ISO 4266: 1987, Petroleum products and hydrocarbons - Determination of sulphur content - Wickbold 
combustion method 
ISO 6251: 1982, Liquefied petroleum gases – Corrosiveness to copper - Copper strip test  
ISO 7941: 1988, Commercial propane and butane – Analysis by gas chromatography  
ISO 8216-3: 1987, Petroleum products - Fuels (class F) - Classification - Part 3: Family L (Liquefied petroleum 
gases) 
ISO 8819:  1987, Liquefied petroleum gases - Detection of hydrogen sulphide - Lead acetate method DRAFT UGANDA STANDARDDUS 971-4 : 2014  
2 © UNBS  2014 – All rights reserved  
 ISO 8973: 1997 , Liquefied petroleum gases – Calculation method for density and vapour pressure  
ISO 13758:1996  Liquefied petroleum gases -- Assessment of the dryness of propane -- Valve freeze method  
ASTM D5305 - 97(2007) Standard Test Method for Determination of Ethyl Mercaptan in LP-Gas Vapour  
3 Terms and definitions 
For the purposes of this standard, the following terms and definitions shall apply   
3.1   
LP Gases  
liquefied petroleum gases consisting of readily liquefiable hydrocarbons predominantly of C 3 and C 4 
compounds that are intended primarily as fuel in domestic, commercial, industrial heating and in spark ignition 
internal combustion engines.  
3.2  
Commercial propane:  
hydrocarbon products composed predominantly of propane and/or propene (C3) ; the remaining part may 
consist mainly of ethane/ethene and butane/butene isomers. It has a distinctive smell that is achieved by 
addition of a stenching agent and  i t’s normally used where high volatility is required   
3.3   
Commercial butane:  
hydrocarbon products composed predominantly of butane and/or butene (C4) ; the remaining part may consist 
mainly of propane/propene and pentane/ pentene isomers It has  a distinctive smell that is achieved by addition 
of a stenching agent and i t’s normally used where low volatility is required 
3.4   
Commercial PB mixture:  
mixtures of predominantly propane and butane (C3 and C 4). It has a distinctive smell that is achieved  by 
addition of a stenching agent and it is   used where intermediate volatility is required. 
3.5   
Aliphatic hydrocarbon :  
Hydrocarbons of the open-chain structure type . 
3.6   
defective  
a test sample of the liquefied petroleum gas that fails in one or more respects to comply with the relevant 
requirements of this standard. 
3.7 
Cross filling 
Practice of one operator filling another operator's cylinder 
 
 
 
3.8 
Lot  
The quantity of LP gases in containers and bearing the same brand name or trademark, grade designation 
and batch identification, from one manufacturer, and submitted at any one time for inspection and testing shall 
constitute a lot. 
 DRAFT UGANDA STANDARDDUS 971-4 : 2014  
© UNBS 2014  – All rights reserved  3 
 4 Requirements 
4.1 General 
4.1.1  Commercial propane 
The commercial propane shall be aliphatic hydrocarbon mixture that consists predominantly of C 3 
hydrocarbons, free from entrained moisture and complies with the appropriate requirements as specified in 
table 1. 
4.1.2  Commercial butane 
The commercial butane shall be aliphatic hydrocarbon mixture that consists predominantly of C 4 
hydrocarbons, free from entrained moisture and complies with the appropriate requirements as specified in 
table 1. 
4.1.3  Commercial BP mixture 
The commercial BP mixture shall be aliphatic hydrocarbon mixture that consists predominantly of C 3 and C 4 
hydrocarbons, free from entrained moisture and complies with the appropriate requirements as specified in 
table 1. 
4.2 Quality Requirements 
4.2.1  When determined in accordance with the methods given in table 1, the properties of LPG gases shall 
conform to the requirements specified. 
Table 1 — Specifications for liquefied petroleum gases  
Characteristics  Comm ercial 
propane  Commercial 
butane  Commercial 
BP mixture  Test 
methods  
Vapours pressure (Gauge) at 40 °C, kPa, 
max.  1434  483 1430A ISO 4256  
Volatility;  
Total acetylene content , mol% max  
Total C 2 hydrocarbon content, mol% max  
Total ethylene content, mol% max 
Total dienes content, mol% max  
Total C 4 and higher, mol % max  
C5 and higher hydrocarbons, mol%  max   
2.0 
8.0 
1.0 
Nil 
7.5 
0.2  
2.0 
Nil 
Nil 
0.5 
Nil 
2.0  
2.0 
8.0 
1.0 
0.5 
Nil 
2.0 ISO 7941  
Residues on evaporation of 100ml, max ml  0.05 0.05 0.05 ISO 13757  
Copper strip corrosion, max  1 1 1 ISO 6251  
Total Sulphur (after stenching), mg/kg max.  185D 140D 140D ISO 2460  
Hydrogen sulphide  Nil  Nil   Nil   ISO 8819  DRAFT UGANDA STANDARDDUS 971-4 : 2014  
4 © UNBS  2014 – All rights reserved  
 Moisture content (dryness)  Pass  - - ISO 13758  
Free water content  - Nil Nil VisualC 
Density at 15°C or relative density at 
15.6/15°C B Should be 
reported  Should be 
reported  Should be 
reported  ISO 3993 
or ISO 
8973.  
Odurization: ethyl mercaptan , µL/mL , min  15 15 15 ASTM 
D5305  
A The permissible vapour pressure of products classified as BP mixtures s hall not exceed 1430 kPa and additionally, shall not exceed 
that calculated from the following relationship between the observed vapour pressure and observed relative density:  
Vapour pressure, max. = 1167 - 1880 (relative density at 15/15.6 °C )  
 
B Although  not a specific requirement, the density or 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)  
C The p resence or absence of water shall be determined by visual inspection of samples on which density or relative density is 
determined.  For shipment s of refrigerated LPG at their atmospheric boiling point, it is essential that the water content is below the 
saturation level at this temperature as determined by a method agreed between buyer and seller.  
D The total sulphur in these specifications do include sulphur compounds for stenching purposes.  
 
Note  Individual contractual agreements, national safety codes, regulations and/or requirements of distribution systems shall be 
complied with in addition to the specifications in table 1. 
4.2.2  Additional information to be supplied by the vendor to the purchaser 
The vendor of the commercial butane or propane shall supply the purchaser with the following additional 
information. 
a) Density: The density, in kilograms per cubic metre at 15 °C, determined by the method in ISO 3993 or 
ISO 8973. 
b) Unsaturated hydrocarbons: The molar percentage of unsaturated hydrocarbons, determined in 
accordance with ISO 7941 
 
4.2.3  Precision and interpretation of tests results 
Most of the methods of test given in table 1 contain a statement of the precision, i.e. the repeatability and 
reproducibility, to be expected from them. However, in cases of dispute, the procedure described in ISO 4259, 
which uses precision data in the interpretation of test results, shall prevail. 
7 Packing and Documentation 
7.1 Packing 
The condition ofcylinders and road tank vehicles shall be such as not to be detrimental to the quality of the 
fuel during normal transportation and storage and shall be approved by an approving authority. 
For safety purposes, all cylinders should not be cross filled among the operators  
7.2 Documentation 
The documentation supplied to the purchaser by the vendor shall include at least the following:  
a) The name of the product, Liquefied Petroleum Gas (LPG); 
b) The brand name of the product; 
c) A reference to the national, regional or international standards complied with 
d) The supplier’s production cod e and the date of production 
e) Precautionary and safety advice in the form of MSDS 
f) Quantity of the product in weight DRAFT UGANDA STANDARDDUS 971-4 : 2014  
© UNBS 2014  – All rights reserved  5 
  
If a transportable container is supplied with the liquefied petroleum gas, it shall also be clearly marked with the 
above information 
8 Sampling and compliance with the standard 
8.1 Sampling 
After checking for compliance with the relevant requirements of 7.1 and 7.2, a  representative sample of non-
refrigerated liquefied petroleum gases shall be taken in accordance with the procedure given in ISO 4257. The 
sample so drawn shall be deemed to represent the lot and shall be tested for the respective properties in table 
1 to determine whether or not the lot complies with the requirements of this standard. 
For refrigerated liquefied petroleum gases a sampling procedure shall be agreed upon between the parties 
concerned. 
8.2 Criteria for compliance 
The lot shall be deemed to comply with the relevant requirements of this standards if, on inspection of the 
containers or tankers in the lot and on testing of the samples taken in accordance with 8.1, no defective is 
found. 
Note  Proper sampling of the liquefied petroleum is extremely important if the test results are to be significant. 
 DRAFT UGANDA STANDARDDUS 971-4 : 2014  
6 © UNBS  2014 – All rights reserved  
 Annex A 
(informative)  
 
Significance of this specifications for liquefied petroleum (LP) gases 
A.1 General 
This specification addresses commercial liquefied petroleum gases consisting of either propane or butane or 
mixtures thereof. Consequently, the important characteristics of these products can be defined and controlled 
by a relatively few simple measurements. The specification test methods provided achieve the desired results. 
The significance of the various tests as they can apply to consumer problems is summarized here. 
A.2 Vapour Pressure, Volatility, and [Relative] Densi ty: 
A.2.1  Vapour Pressure —indirect measure of the most extreme low-temperature conditions under which 
initial vaporization can be expected to take place. It can be considered as a semi-quantitative measure of the 
amount of the most volatile material present in the product. It can also be used as a means for predicting 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 temperature of the product, is a measure of 
the amount of least volatile fuel component present in the product. Coupled with a vapour pressure limit, it 
serves to assure essentially single-component products in the cases of commercial propane and commercial 
butane fuel types. When volatility is coupled 0with a vapour pressure limit which has been related to density or 
gravity, as in the case of the commercial PB-mixture type of fuels, the combination serves to assure 
essentially two component mixtures for such fuels. When coupled with a proper vapour pressure limit, this 
measurement serves to assure that special-duty propane products will be composed chiefly of propane and 
propylene and that propane will be the major constituent. 
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 relative density is of importance in meeting transportation and 
storage requirements it is always determined for all liquefied petroleum gas products. 
A.3 Other Product Characteristics 
While the vaporization and combustion characteristics of commercial liquefied gas products are completely 
defined for the normal use applications by vapour pressure, volatility, and relative density, as given in A.2, 
there are other properties which either affect or might affect the results obtained in some specific use 
applications. For that reason, limits are specified for residue content, copper corrosion, sulphur content, 
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 hydrocarbon materials present in the product 
which are substantially less volatile than the liquefied 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 limit the 
permissible concentration of residue materials can result in troublesome deposits or regulating equipment can 
become fouled, or both. In gas processing plants, LP gas generally is produced relatively free of residues, but 
the product can become contaminated by heavier hydrocarbons and other organic compounds during 
distribution, especially in multiproduct pipelines or while it is in contact with elastomers used in hoses. The 
current limit on residue contamination, while generally satisfactory for many conventional uses, may not be 
suitable for newer applications such as fuel cells and microturbines without some form of remediation. DRAFT UGANDA STANDARDDUS 971-4 : 2014  
© UNBS 2014  – All rights reserved  7 
 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 commonly 
used in many types of utilization, storage, and transportation equipment. The copper corrosion test will detect 
the presence of elemental sulphur and hydrogen sulphide, which is highly toxic. The copper corrosion limits 
also provide assurance that the LP-Gas will not contain 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 addition, 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 liquefied petroleum gas products. 
Historically these products were lower in sulphur content than most other petroleum-derived fuels. This is 
generally no longer the case in areas where gasolines are typically below 30 mg/kg (ppm by mass) sulphur 
and diesel fuels are less than 15 mg/kg (ppm by mass) sulphur. The limit on sulphur content minimizes 
sulphur oxide emissions and limits potential corrosion 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 above ab out -26°C. The purpose of moisture content control 
is to provide assurance that pressure reducing regulators and similar equipment will operate consistently 
without troublesome freeze-ups caused by the separation of dissolved water from the product. 
The presence of an antifreeze agent such as methyl alcohol which prevents separated water from freezing 
can allow use of propane containing excessive dissolved water in many applications. 
Note Commercial propane and special duty propane should be produced to comply with the moisture content 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 are subsaturated with water at most ambient temperatures. 
They should be maintained dry during storage and distribution. A de-icer such as methyl alcohol (methanol) 
should not be added to these products without specific agreement and approval of the purchaser. During 
short-term upsets in production, or inadvertent contamination by trace water during storage or distribution, 
addition of 50 ppm methyl alcohol has proven to be acceptable to prevent valve freezing in normal 
applications. For guidance, based on historical experience and phase separation data, the maximum 
cumulative additi on of methyl alcohol should not exceed 200 ppm by volume. 
A.3.5 Free Water Content —of importance only on the commercial PB-mixtures and commercial butane type 
products. These two types of products are normally used under ambient conditions which are mild and, as a 
consequence, the only requirement is vigilance to ensure that no free water is present. 
 DRAFT UGANDA STANDARDDUS 971-4 : 2014  
8 © UNBS  2014 – All rights reserved  
 Bibliography 
[1] ISO 9162: 1989, Petroleum products – Fuels (Class F) – Liquefied petroleum gases - Specifications  
[2] ASTM D1835 – 11, Standard specifications for liquefied petroleum (LP) Gases  
[3] SANS 1774 , Liquefied petroleum gases  
[4]  
  
. DRAFT UGANDA STANDARDDUS 2011-4 : 2014  
© UNBS 2011 – All rights reserved  9 
 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 conjunction 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 
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 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.  
 
 DRAFT UGANDA STANDARDDUS 971-4: 2014    
 
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