This is probably one of the most common and greatest fears of barbecue lovers: Will the LPG cylinder explode if it sits in the sun for too long? Even if for some, the combination of gas cylinder and direct sunlight is an explosive mixture in the truest sense of the word, these fears are unfounded. We’ll show you why.
Anyone who has hosted a barbecue with an LPG grill in the blazing sun may have already wondered about whether the gas cylinder poses any danger. If it’s not sitting in the cupboard under the gas barbecue, the cylinder is unprotected in the sun. Most people still remember from their physics lessons: Gas expands when heat is added.
Why the LPG cylinder isn’t dangerous
Even if this is the case here, there is absolutely no danger to life and limb.
LPG cylinders are never filled to 100%. Almost 20 percent of the cylinder is not filled with the liquid phase of the medium. There has to be room above the liquid phase for a gaseous buffer to form. This ensures that the cylinder won’t immediately reach its capacity limits when the temperature increases.
No risk at normal temperature
Based on the specifications, gas cylinders must be designed for a pressure of at least 50 bar. At an ambient temperature of 20 degrees Celsius, there is a pressure of 7 to 8 bar in the cylinder. Even at a temperature of 100 degrees Celsius, the pressure within the cylinder would not reach 50 bar. So, unless you’re planning on cuddling the gas cylinder in a Finnish sauna, you don’t need to worry about any danger.
Last but not least: If the pressure in the cylinder does actually reach 30 bar, there is also a safeguard. A safety valve responds at just this temperature, and releases the overpressure into the atmosphere. Once its response pressure drops below this, the valve closes again automatically. Just to put your mind at ease, though, the vapour pressure curve for propane shows that a pressure of over 30 bar can only be expected above a temperature of around 80 degrees Celsius.
The town of Kitzingen, Lower Franconia, which is not far from our company headquarters, is the current holder of the heat record in Germany, with a value of 40.3 degrees Celsius measured there twice. Even if you park the gas cylinder in the blazing sun at this sweltering temperature, the container is not going to explode while you’re barbecuing.