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Author: Subject: Propane tank in full sunlight: dangerous ?
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[*] posted on 26-5-2018 at 23:59
Propane tank in full sunlight: dangerous ?

I found a video which I made a few months ago of a propane tank in full sunlight at 35 C and considered it was dangerous.

The tank is labeled 'keep cool' so can this really have a risk of a BLEVE ?

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[*] posted on 27-5-2018 at 01:26

I don't think your topic should be created here in the energetics forum.

Anyway. Answering your question, it depends.
Whoever designed the tank did so with a specific mindset to resist X things and be safe. If the tank was built with a safety factor enough to resist the greater pressures caused by the expansion of the gases, then yes, it would be safe, but not ideal.
And also, whoever designed the tank, if they thought about how hot the tank could get when exposed to strong sunlight, they should've performed the calculations that would predict how much the gases would expand and how much pressure they would exerce against the walls, and then on top of that, a safety factor. You never build things just strong enough to resist how they are meant to be used, you always make it stronger than the theoretical. And how much stronger it will be depends on the application of the tool/object and how dangerous and bad an accident caused by the malfunction of such tool/object would be. For exemple, firearms barrels, if ruptured, could easily destroy a finger of yours, or even worse, even kill you. Engineers usually add a safety factor of 8 or 10 to firearms barrels, which means that they could resist 10 times the pressure and stresses that they are meant to resist in normal operating conditions.

So, if the propane tank says "keep cool", keep it cool. Someone put some thinking when designing that tank and they didn't want it to get exposed to sunlight or anything that would normally get it hotter than normal room temperature.

[Edited on 27/5/18 by joseph6355]

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[*] posted on 27-5-2018 at 03:33

If you head to a big box store (Walmart, Home Depot) and look where the entrance to the building faces the parking lot, you will see many wire cages containing propane tanks for exchange. In summertime at a parking lot the temperature can easily be 35 degrees Celsius or more, and I'm sure the pavement gets up to 60 or 70 degrees. Yet in all the stores across American there haven't been a single incident so far as I'm aware of.
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[*] posted on 27-5-2018 at 13:51



LPG-Propane Cylinder Pressure Rating - Operating Pressure LPG cylinders and vessels are designed to handle much higher than normal operating pressures.
The typical cylinder would probably only burst with pressures over 6895 kPa or 1,000 PSIG. Pressure gaugeThat's about 5x the normal pressure.
This would vary by the manufacturer and the cylinder itself.

LPG cylinders have pressure relief valves incorporated into the main valve. The typical pressure relief valve setting is 2585 kPa or 375 PSIG. So, the cylinder would never actually go above this, as the valve would open and lets some gas escape, limiting the pressure inside the cylinder.

LPG cylinder pressure varies with temperature.
Even at 70ºC (158ºF), well beyond normal ambient temperatures, the pressure would only be 2482 kPa (360 PSIG). So, not only wouldn’t it approach bursting pressure (≈ 1,000 PSIG) but, under normal circumstances, it would never even reach the 375 PSIG required to trigger the pressure relief valve.

So sunlight doesn't really pose a risk.

[Edited on 27-5-2018 by Twospoons]

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