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Material safety data sheets (MSDS) lists the materials "Flash Point". I know there are different methods to arrive at this information (closed cup, open cup). But what is the information telling us. Say for instance a fluid has a flash point of 115 F (46.1C). Ok now what?
At 115 deg F. the liquid you have will ignite in the presence of an open flame.
It means what you have is volatile and needs to be stored and handled accordingly. Storage should be in a closed, pressurized tank or floating roof tank with adequate vents and/or pressure relief to a flare. Normally, atmospheric storage is limited to flash points above 140 F.
As jay165 clearly stated flash point is primarily important from a fluid handling standpoint.
ASTM has half a dozen procedures to determine flash points, see E502-84(2000). Flash point is a measure of the temperature to which the fluid (generally a fuel) must be heated to produce an ignitable vapour-air mixture above the liquid when exposed to an open flame.
A fluid with too low a flash point could be a fire hazard, subject to flashing, and possible continued ignition and explosion. Furthermore, a low-flash point in a heating or power generating fuel may indicate the presence of more volatile and explosive components such as gasoline.
Insurance companies, government agencies, and private users set mandatory limits on flash points because of fire hazard considerations, which must be taken into consideration when establishing fluid (especially heating and power generation fuel) specifications.
Flash point by closed testers are normally employed for fuel distillate hydrocarbons such as kerosine, gas oils, etc., and for residual fuels, because these procedures more normally approach the conditions of storage of fuel in tanks.
As a PS let's say that flash points and self-ignition points are not generally related.
Thank you both for your reply. We use D-Limonene as a heat transfer fluid (good properties @ -65 to 200F) however we have a customer who is jittery about this fluid's flashpoint. I am just trying to calm them down.
You should know the flash point incase of heat transfer fluids. A periodic check of fluid flash point is needed, for a reduced flash point indicates deterioration of the heat transfer fluid.
If you have a pressurized system, it is better to know the open cup flash point value (to take care incase of leakage).
MTBE has a flash point of -34C (-29F), how dangerous is this? We are storing MTBE in typical floating storage tanks approximately at atmospheric pressure.
I would not use d-Limonene as a heat transfer fluid above 100 F unless the entire environment it is used in is a Class 1, Division 2, NEC designed: in short, explosion proof equipment and working tools/procedures all around! I've been safety engineer for a chemical plant handling combustible and flammable definition materials.
It's flash point is 140 F. While in it's closed piping in a perfect world, it would be okay. In the real world, a simple leak or spray (sometimes under pressure especially for long distances), can become atomized and very easily ignited by an open flame or spark.
There are lots of other suitible HT fluids with much higher FP and even non-flammble; just Google-search-it.
Flash Point is for the temperature when the fluid itself gives off enough vapor in the right percentages to ignite with a small spark. When you atomize it or have an open flame, the FP is meaningless. Flash Point of an atomized/vapor/gas has be treated as if it were below zero FP.
The difference routinely between close and open cup and the different styles is usually insignificant to the real world application for fire AND explosion prevention. The FP should only be considered like a nominal number - like a nominal 2x4 wood piece is really as much as 1/2 inch thinner.
Many HT fluids are operated at temperatures higher than their flash points. Safety precautions are always recommended. D-Limonene is sometimes provided with an antioxidant such as BHT. For more information on this chemical one could visit
My experience with heat transfer fluids is that their flash point does decrease with time as decomposition occurs (faster of course as the working temperature goes up)and you need to monitor that and change the fluid eventually.
There's no problem in letting the flash point drop below the operating temperature as long as you realise that the system is then a flammable one and so all potential leak points must be assessed and equipment in the affected zone must be of a suitable standard. In the EC, this is known as Area Classification, and I guess there's a similar system in the USA.
You DO need to worry if the auto ignition temperature falls to below the highest operating temperature, as any leak would then self-ignite! So you need to test samples of the fluid for both parameters as a matter of routine.
As stated above, sprays forming mists are particularly dangerous as they can catch fire very easily, and they can travel some distance, making classified zones quite large. A thorough study of the system is mandatory if you think you are going to get the flash point below the operating temperature.
I´m working with an oxygen enriched zone. However I´m unable to find AIT (and flash point) for fuel in these environments. All data I have founded so far concerning AIT and flash point are restricted for air.
I use Jet Fuel: AIT = 210C (410F) and Flash Point = 162C (110F).
The open cup test approximates the conditions above an open pan or vat. Think of a saucepan on the stove with the lid off. The closed cup approximates the conditions found in an atmospheric storage tank like an API 650 tank. That is a closed tank with a small vent to atmosphere or a breather valve.
Edmacs, I know the Bureau of Mines produced data ages ago about the LEL and UEL for various materials in different oxygen concentrations as I used it to make up the flammibility curve for ethane as we purged out a large atmospheric storage tank.
However, I no longer have those references. You might want to check http://web.umr.edu/~nenat/subs/cdgeo.html and see if you can get some sort of interlibrary loan depending what you have available.
Thanks for your support. However I was unable to find data about fuel jet auto ignition in environments with enriched oxygen concentrations.
I don't think I'll be able to get some sort of interlibrary loan because I'm in Brazil. Maybe I may find something in Fire Protection Handbooks in the library. I 'll have to check!
edmacs - I have a plot of Autoignition Temperature deg C versus % v/v oxygen for JP-6 fuel at 101 kPa abs. There is a very small drop in AIT from 20% oxygen to 100% oxygen. The drop is from about 230 C to about 220 C. The inert is nitrogen. The source reference is Kuchta, Bartkowiak, and Zabetakis, Autoignition of Hydrocarbon Jet Fuel, US Bureau of Mines Rep Invest. 6654, 1965.
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Flash point
