BS/EN 1839-2017 pdf download.Determination of the explosion limits and the limiting oxygen concentration(LOC) for flammable gases and vapours.
has to be taken into account. Up to 200 °C, the LEL decreases more or less linearly between 30 % and 50 % of the value estimated for 20 °C.
There is currently no method which readily estimates the UEL.
When it is established that a given test mixture will not ignite, it is recommended that the quantitative composition of the non-ignited test mixture flowing out of the test vessel is analysed in order to determine whether any errors have arisen either with the metering devices or due to leakage.
4.2 Method T (‘tube method)
4.2.1 Detailed method
The test mixture flows through the cylindrical test vessel from the bottom upwards to the top until the contents previously in the test vessel have been completely replaced. Then, under quiescent conditions, an ignition is Initiated using a series of induction sparks. It is observed whether or not flame detachment occurs. When determining the LEL or the UEL (explosion criterion — flame detachment) the test substance content of the test mixture is varied stepwise until an ignition of the mixture just fails or until it is established that there is no explosion range.. When determining the LOC the test substance content of the test mixture as well as the inert gas content is varied stepwise until an ignition of the mixture just fails.
4.2.2 Reagents and materials
4.2.2.1 Air, which shall be free of water (sO,1 mol% water vapour absolute) and oil (≤O1 g / m3 oil)
If synthetic air is used, it has to be stated in the report.
4.2.2.2 Inert gases, the purity of the inert, or the mixture of inerts, shall be 99,8 % mol. or better
If a mixture of inerts is used, the composition of the mixture shall be stated in the test report.
4.2.2.3 Flammable substances, which may be either a single substance or a defined mixture of substances or a process sample (of known or unknown composition)
When a single substance or a defined mixture of substances is used, the purity of each substance shall be 99,8 % mol. or better. In the case of a mixture of substances or a process sample of known composition, the precision of the composition shall be stated in the test report. For a process sample with unknown composition, the sample shall be defined as precisely as possible (e.g. process conditions).
If the flammable gas is derived from a liquid containing more than one component, the gas phase composition can differ from the composition of the liquid phase. When large volumes of the gas are removed, the composition of both the liquid and gas phases can change with time. For these reasons, the test sample shall be taken from the liquid phase.
4.2.2.4 Heat-resistant, chemically inert material for gaskets and adhesive mountings
Sample containers shall be kept closed before and after sampling to avoid changes in the sample composition within the container (e.g. loss of volatile components from mixtures), If a sample container contains a mixture with both gaseous and liquid phases present, the mixture composition of the two phases will be different. Under such conditions, it is recommended that the test substance sample be removed from the liquid phase. lithe sample is taken from the gaseous phase, account shall be taken of the difference in composition.
BS EN 1839:2017
EN 1839:2017 (E)
4.2.3 Apparatus
4.2.3.1 Test vessel
The test vessel is an upright cylindrical vessel made of glass or other transparent material (e.g. polycarbonate) with an inner diameter of (80 ± 2) mm and a minimum length of 300 mm.
The vessel is equipped with an inlet pipe with a three-way valve for the test mixture, located at the bottom, and an outlet pipe and pressure vent in the upper part.
The bottom and top may be made of other material. However, the material shall be free of any catalytic effect and resistant to corrosion from the test mixture or the reaction products.
4.2.3.2 Ignition source
A series of induction sparks between two electrodes is used as the ignition source. The electrodes shall end (60 ± 1) mm above the bottom of the test vessel.BS/EN 1839-2017 pdf download.