Bunker Supplement No. 12 – December 1999
What is Flash Point and how does it differ from flammability?1
The parameter of Flash Point of petroleum products is defined by the diverse methods and equipment used to determine the parameter result. Without discussing each test method in detail the Flash Point result shown on a test report will depend upon:
The Testing method used for the product and the equipment associated with the method,
The Flash Point testing equipment used (e.g. Pensky-Martins closed cup, Tag, “Setaflash”, etc.),
The rate of heating and stirring of the sample within the test equipment,
The rate and/or method used for the submission of the ignition source to the evolved vapour within the test cup,
So what is Flash Point? It is the temperature of the liquid at which sufficient hydrocarbon vapour has evolved from the test liquid under the prescribed test conditions, such that when an ignition source is presented to the vapour/air mixture in the test apparatus, “combustion” of the vapour occurs.
The Flash Point test method proposed for the new ISO 2719 standard will be by the Pensky-Martins method with the Institute of Petroleum test method number 34/00 or 34/01 depending upon when the test is finally validated. Unlike the current procedures used for the determination of this parameter the test method will be divided into two differing procedures, A and B, with procedure B being that used for Flash Point determination of Bunker Fuel Oils. In order to avoid confusion and to compare “like with like”, care should be exercised when reviewing test reports with regard to this parameter, the correct test method has been used and is properly identified on the test report with the “A or B” subscript.
Flammability implies the ability for a material to burn without the presence of a continuous ignition source at a specific temperature once having been ignited by a source. The concept of Flammability, however, raises two questions; namely, the flammability of the vapour from a liquid or the flammability of the liquid itself. The Flammability of vapour evolved from a liquid can be determined by the mixture of the vapours/gases present within the vapour phase above the liquid. The flammability will conform to the normal “flammability envelope” diagram found within the ISGOTT publication for the Oxygen/hydrocarbon vapour concentrations.
The flammability of liquid is determined by testing using a specific test method entitled “Flash Point (open) and Fire Point by means of the Pensky-Martens Apparatus”. This method determines the temperature under strict laboratory conditions at which a liquid volume, in an open container, will firstly, “flash” when an ignition source is presented above the surface of the liquid and thereafter ignite and continue to burn (fire point) for a period of 5 seconds. Clearly these respective temperatures will be higher than the traditional flash point for the same bunker fuel sample.
So, what is the difference between the Flash Point and flammability of a bunker fuel? The Flash Point of a bunker is a laboratory determined temperature at which adequate combustible vapour exist within the test equipment to generate combustion given an ignition source. This test does not have any time element associated with it and therefore does not allow for or simulate the slow build up of combustible vapour within a head space of a bunker tank over a period of time notwithstanding the fact that the temperature
1 Further reading – The Flammability Hazards associated with the Handling, Storage and Carriage of Residual Fuel Oils; OCIMF, December 1989
Agenda for the CTC #32Page 36 of 39
To be held in Panama City on the 09 April 2008 Issue No. 1
Our Ref.: AGO-22713/1000003Approved by: H.N. Snaith