TRINIDAD AND TOBAGO STANDARD 
 
 
 
COMPULSORY 
 
 
 
SPECIFICATION FOR  
LIQUEFIED PETROL EUM GASES (LPG) 
(1st Revision) 
 
PCTTS 59: 20XX 
(Replaces TTS 11 40 500: 1979) 
 
  
Copyright © 
This National Standard issued by the Trinidad and Tobago Bureau of  Standards is copyright protected by the Standards Act No. 
18 of 1997 and neither this document nor any extract from it ma y be reproduced, stored in a retrieval system or transmitted in 
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from the Trinidad and Tobago Bureau of Standards. 
Request for permission to reproduc e should be addressed as follows: 
Executive Director 
Trinidad and Tobago Bureau of Standards 
Century Drive, Trincity Industrial Estate, 
Macoya, Tunapuna, 
P.O. Box 467, Port of Spain 
Trinidad and Tobago 
Phone: 662-TTBS E-MAIL: ttbs@ttbs.org.tt 
 
Reproduction may be subject to royalt y payments or a licensing agreement. 
 
                      Editorial Draft approved to go to:      THE PUBLIC COMMENT STAGE  
           Signed _____________________________________             Date:  ______________ 
                            Chairperson – Editorial Committee  
 
                     G r .   
 PCTTS 59: 20XX 
 iiGENERAL STATEMENT 
The Trinidad and Tobago Bureau of Standards (the Bureau) is a body corporate established under 
the authority of the Standards Act No. 18 of 1997 (herein after referred to as the Standards Act). 
In accordance with the Standards Act, the Bure au shall promote and encourage the development and 
maintenance of standards and further shall establ ish standards for the following: to improve goods 
produced or used in Trinidad and Tobago; to ensure industrial efficiency and development; to promote public and industrial welfare, health and safety; and to protect the environment. 
The Bureau develops standards through consultati on with relevant interest groups, and public 
comment is invited on all draft standards before th ey are declared as Trinidad and Tobago Standards 
in accordance with the provisions of the Standards Act. 
The Bureau is the legal custodian of Trinid ad and Tobago Standard Marks, which are issued in 
accordance with the Standards Act.  When a Trinidad and Tobago Standard Mark appears on any product, or in connection with any service, proce ss or practice, it provides assurance that such a 
product, service, process or practice c onforms to a Trinidad and Tobago Standard. 
The Bureau’s Standards Information Centre maintains a reference library of standards, including local, 
regional and international standards and is the na tional node of the International Organization for 
Standardization Information Network (ISONET).  The Centre also acts as the sales agent for the 
publications of foreign and international standards organizations. 
NOTE In order to keep abreast of progress in the industries concerned, Trinidad and Tobago Standards are 
subject to periodic review.  Suggestions for improvements are welcome. 
 PCTTS 59: 20XX 
 iiiAMENDMENTS ISSUED SINCE PUBLICATION 
AMENDMENT NO.  DATE OF ISSUE  TEXT AFFECTED  
   
   
   
   
 
 PCTTS 59: 20XX 
 ivATTACHMENT PAGE FOR TTBS AMENDMENT SHEETS PCTTS 59: 20XX 
 vTRINIDAD AND TOBAGO STANDARD 
 SPECIFICATION FOR LIQUEFIED PETROLEUM GASES (LPG) 
TTS 59: 20XX 
 
The Specification Committee responsible for the form ulation of this Trinidad and Tobago Standard is 
as follows: 
SPECIFICATION COMMITTEE FOR LIQUEFIED PETROLEUM GASES 
Members           Representing 
Dr. Angelus Pilgrim  (Chairman)      University of the West Indies, Faculty  
             o f  E n g i n e e r i n g   
Mr. Steve Hilaire          Petroleum Company of Trinidad and  
             Tobago Limited 
Mr. Adrian Nunez          Phoenix Park Gas Processors Limited 
   M r .  R a w l e  M a i c o o                 
M r .  F a z a l  K h a n           M i n i s t r y  o f  W o r k s       Mr. Kishan Kumarsingh        Environmental Management Authority 
Mr. Shiraz Mohammed        Academy of Automechanics 
Ms. Eka Rudder-Fairman        Ca ribbean Research Institute (CARIRI) 
Mr Wendell Williams Automotive  Dealers Association of 
Trinidad and Tobago (ADATT) 
Mr. Ricardo Rodriguez (Technical Secretary)  Trinidad and Tobago Bureau of Standards
     
 
 
 
 
  
 
  PCTTS 59: 20XX 
 viContents  
              
             Fo rewo rd .......................................................................................................... ....................................... 1  
1 Scope ........................................................................................................................ .............................. 2  
2 Normative refere nces......................................................................................................... ..................... 2  
3 Terms and defini tions........................................................................................................ ...................... 3  
4 General r equireme nts ......................................................................................................... .................... 4  
4.1 Gene ral .................................................................................................................... ............................... 4  
4.2 Compositi on of LPG......................................................................................................... ....................... 4  
4.3 Stenching of LPG........................................................................................................... ......................... 4  
5 Samp ling ..................................................................................................................... ............................ 4  
6 Testing...................................................................................................................... ............................... 4  
 
Table 1 — Requirements for Li quefied Petrol eum Gases ........................................................................... ......... 5  
 
 
  
 
  
 
  
 
  
 
  PCTTS 59: 20XX 
 vii 
  
 
  
 
  
 
  
 
  
 
  
 
  
   
 
 
(This page was intentionally left blank) PCTTS 59: 20XX 
 1Foreword 
These requirements were declared a Trinidad and Tobago Standard on ……………., after the draft 
finalized by the Specification Committee for Liquef ied Petroleum Gases (LPG), had been approved by 
the Bureau. 
The Trinidad and Tobago Bureau of Standards has recommended that this standard be declared a 
compulsory standard to protect the consumer or user against danger to health and safety, to protect the environment and to ensure a minimum accept able quality of LPG produced in Trinidad and 
Tobago. 
This first revision of the standard will become effective as a compulsory standard on a date to be 
notified by the Minister responsibl e for trade and industrial development, in a notice to be published in 
the Trinidad and Tobago Gazette, as required by th e Standards Act. This revised version replaces 
TTS 11 40 500: 1979 and contains updated test met hods for the composition, volatile residue, total 
sulphur content and stenching of LPG 
By specifying the blends, it is expected that acceptable product q uality will be established and used 
for ensuring LPG compliance. As a safety feature,  a limit for a stenching agent has been included for 
leak detection.  
Although the procedure for the use of LPG is noted to  be fairly safe, the user is reminded of the 
potential dangers that exist for a pr essured system. One such danger is  that of explosion, and users 
are encouraged to store LPG tanks away from open flames or a safe distance away from high 
temperature operations. 
In preparing this standard the following references were consulted: a) International Organization for Standardization  
 ISO 9162-1989, Petroleum products - Fuels (Class F); 
b) American Society for Testing and Materials   ASTM D 1835-05, Standard specification fo r liquefied petroleum (LP) gases; and 
c) Gas Processors Association 
 GPA 2140-91, Standard method for test for LPG - Specifications for liquefied petroleum gases 
 and test methods, USA. 
 PCTTS 59: 20XX 
 21 Scope 
This standard specifies the requirements for th e sampling, testing methods and determining the 
quality of liquefied petroleum gases (LPG) in Trinidad and Tobago. 
The requirements of this standard do not apply to th e quality of LPG for use as an aerosol propellant 
or as petrochemical feedstock or  for any other industrial uses. 
2 Normative references 
The following normative documents contain provisions which, through reference in this text, constitute 
provisions of this national standard. For all refe renced standards, subsequent amendments to or 
revisions of any of these publications shall apply. 
2.1 ASTM International   
ASTM D 1265-05 Standard practice for sampling liquefied petroleum LP gases (manual method). ASTM D 1267-02 (2007) Standard test method for vapour pressure liquefied petroleum gases. 
ASTM D 1835-05 Standard specification for liquefied petroleum (LP) gases. ASTM D 1837-02a (2007) Standard test method fo r volatility of liquefied petroleum gases. 
ASTM D 1838-07 Standard test method for copper strip corrosion by liquefied petroleum gases. 
ASTM D 2158-05 Standard test method for residues in liquefied petroleum gases. ASTM D 2597-94 (2004) Standard test method for anal ysis of demethanized hydrocarbon liquid 
mixtures containing nitrogen and carbon dioxide by gas chromatography. 
ASTM D 2598-02 (2007) Standard practice method for calculation or certain physical properties of 
liquefied petroleum gases from compositional analysis. 
ASTM D 2713-91 (2001) Standard test method fo r dryness of propane (Valve freeze method). 
ASTM D 3120-06 e1 Standard test method for trace qua ntities of sulphur in light liquid petroleum 
hydrocarbons by oxi dative microcoulometry. 
ASTM D 3246-05 Standard test method for sulphur in  petroleum gas by oxidative microcoulometry. 
ASTM D 3700-07 Standard practice for obtaining LPG samples using a floating piston cylinder. 
ASTM D 5305-97 Standard test method for determi nation of ethyl mercaptan in LP-gas vapour. 
ASTM D 5453-06 Standard test method for determination of total sulphur in light hydrocarbons, spark 
ignition engine fuel, diesel engine fuel and engine oil by ultraviolet fluorescence. 
 
 PCTTS 59: 20XX 
 32.2 International Organiza tion for Standardization  
ISO 3993-1984 Liquefied petroleum gas and light hydroc arbons - Determination of density or relative 
density - Pressure hydrometer method. 
ISO 4256-1996 Liquefied petroleum gases - Determ ination of vapour pressure - LPG method. 
ISO 4257-2001 Liquefied petroleum gases - Method of sampling. ISO 4267-2: 1988 Petroleum and liquefied petroleum produ cts - Calculation of oil quantities - Part 2: 
Dynamic measurement. 
ISO 6251-1996 Liquefied petroleum gases - Co rrosiveness to copper - Copper strip test. 
ISO 7941-1988 Commercial propane and butane - Analysis by gas chromatography. 
ISO 8819-1993 Liquefied petroleum gases - Detectio n of hydrogen sulphide - Lead acetate method. 
ISO 9162-1989 Petroleum products - Fuels (class F)  - Liquefied petroleum gases – Specifications.  
3 Terms and definitions 
For the purposes of this national standard, the following terms and definitions shall apply. 
3.1 commercial means used for domestic or industrial purposes. 
3.2 commercial butane  means a hydrocarbon product for us e where low volatility is required. 
3.3 commercial propane/butane mixtures  mean mixtures of propane and butane for use where 
intermediate volatility is required. 
3.4 commercial propane  means a hydrocarbon product for us e where high volatility is required. 
NOTE Commercial propane is suitable for certain low severity internal combustion engine applications. 
3.5 LPG  means liquid petroleum gases consisting of commercial butane, commercial propane, 
commercial butane-propane mixtures and special duty propane blends. 
3.6 residual matter  means a measure of the concentrati on of soluble hydrocarbon materials 
present in the product which are substantially le ss volatile than the liquefied petroleum gas product 
being sampled. 
3.7 special duty propane  means a high quality product composed primarily of propane, which 
exhibits superior anti-knock characteristics when used in an internal combustion engine. 
3.8 vapour pressure  means an indirect measure of the most  extreme low temperature conditions 
under which initial vaporization can be expected to take place. PCTTS 59: 20XX 
 44 General requirements 
4.1 General 
4.1.1 Liquefied petroleum gases (LPG) s hall consist essentially of C 3 and C 4 alkanes or alkenes, or 
mixtures of these.  
4.1.2 Liquefied petroleum gases shall not contain inher ent harmful quantities of toxic or nauseating 
substances and shall be free from entrained water. 
4.2 Composition of LPG 
4.2.1 Commercial Butane - Propane Mixture - shall be a hydrocarbon mixture consisting of: not less 
than seventy percent (70%) by liquid volume of commercial propane; and commercial butane. 
4.2.2 Special duty propane shall be a product compri sing propane of not less than ninety percent 
(90%) liquid volume. 
4.2.3 The additional requirements for the commercia l butane, commercial propane, commercial 
propane - butane mixtures and special duty propane are listed in Table 1, together with the limits and 
recommended methods of test. 
4.2.4 Commercial butane and commercial propane shall ha ve composition as stated in Table 1 and 
shall not contain free or suspended water detectable by visual inspection. 
4.3 Stenching of LPG 
All LPG gases shall be odorized by the addition of a stenching agent that is  rendered distinctive and 
unpleasant, prior to the delivery to a distributing pl ant. Such a stenching agent shall be detectable, by 
a distinct odour, down to a concentration in air of not over 20% of the lower limit of flammability when 
tested in accordance with ASTM D 5305. 
5 Sampling 
To ensure the integrity and reliability of test re sults proper sampling techniques are important. 
Samples shall be drawn in accordance with ASTM D 1265, ASTM D 3700 or ISO 4257. Where there 
is a dispute over sampling integrity between AST M D1265 and ASTM D 3700 requirements, ISO 4257 
shall be used as the referee sampling procedure. 
6 Testing 
All liquid petroleum gas samples drawn according to  the requirements of clause 5 shall have their 
various compositions tested in accordance with the test methods of Table 1. PCTTS 59: 20XX 
 5Table 1 — Requirements for liquefied petroleum gases  
Requirements Commercial 
butane Commercial 
propane Commercial  
butane/propane 
mixture Special duty 
propane Test methods
 
Composition Predominantly 
butane and may 
contain butylene Predominantly 
propane and may 
contain propylene Mixture of butanes 
and/or propylene not less than 
90% liquid 
volume 
percent 
propane ASTM D 2597 
ISO 7941 
Vapour pressure at 37.8 oC kPa (max) 
 
(psig)  (max) 
  
483 
 
70  
1 434 
 
208  
1 434 
 
208  
1 434 
 
208 ASTM D 1267 
ASTM D 2598 
ISO 4256 
 
2.2  
-38.3 
 
 
  
2.2 
 
 
  
-38.3 
 
 
 ASTM D 1837 Volatile Residue: 
Temp. 95% 
evaporation  oC 
(max) 
 
Butane and heavier, 
liquid volume % 
(max) 
  
-  
2.5  
 
-  
2.5 ISO 7941 
ASTM D 2597 
Pentane and 
heavier, liquid 
volume %  (max)   
2.0  
-  
2.0  
- ISO 7941 
ASTM D 2597 
Propylene, 
volume % (max) - - - 5.0 ASTM D 2597 
Residual  Matter on 
evaporation, ml per 
100 ml (max) 
  
- 
  
.05  
-  
.05 ASTM D 2158 
Copper Strip 
Corrosion (max)  
 No 1 No 1 No 1 No 1 ISO 6251 
ASTM D 1838 
aTotal sulphur (on 
the unstenched 
product), ppmw 
mg/kg  (max) 
 140 180 180 123 ISO 8819 
ASTM D 5453 
ASTM D 3246 
Free water content 
 None - None - ASTM D 1835  
Moisture content  - Pass - Pass ASTM D 2713  
Stenching limit                                                                                                                                                 ASTM D 5305 
                                                              10 – 50 ppm                                                                                       
a Total sulphur limits do not include stenching agent.