Hello Ian
Question "I don't understand your reasoning regarding water getting into a regulator. Surely if water can get in, the regulator is not fit for purpose as then gas could also escape the same way water is getting in."
A regulator has a chamber that is divided by a flexible diagram. On one side is the gas, and on the other is the atmosphere. When we say a regulator has an output pressure of 30mBar, we actually mean +30mBarrealtive to the atmospheric pressure. For the regulator to maintain that pressure differential, the air side of the chamber has to ventilate with the external atmosphere. It does that through a small hole. If you check the installation instructions for regulators you will see they call for the regulator to be protected from rain or other sources of water.
There are two dangers of water getting in to the air side of the chamber, one is the spring that biases the diagram, may start to corrode and eventually fail, and secondly as the regulator is effectively the expansion chamber for the high pressure gas from the bottle, as it expands it cools. It may cool the air side sufficiently for any water to turn to ice, which will obviously compromise the action of the spring and diaphragm.
I encountered a problem on a customer's caravan once where the gas pressure was widely out and variable. I found that a price sticker had be stuck over the breather hole. Removing the sticker corrected the problem.
Question "Water could not get in until all the gas had expired"
For the reasons stated above, there is no communication between the gas side and the air side in the regulator so admittance of water to the air side is not dependant on the gas having run out.
Question "The chances of a gas bottle exploding due to sunlight heat are probably impossible"
To a large extent that may be true. Calor and some other suppliers actually incorporate a pressure relief valve in the brass valve assembly. Under direct sunlight, the pressure in the bottle can rise substantially, and the excess pressure may be vented. That obviously has safety implications as the vent gas may be ignited. It is unlikely that any these bottles would explode, because for the gas to ignite it has to have enough oxidant (Oxygen) available, and there is none inside the an LPG bottle. But the venting will feed an external flame. If the make of bottle does not have a PRV, then the internal pressure may continue to build. In theory there is a possibility that the bottle may rupture due to internal pressures, and that would be catastrophic. Propane has more potential for that as its temperature related vapour pressure is much higher than Butane's.
Question "Doesn't gas have a water content anyway"?
LPG (liquefied Petroleum gas) is a hydrocarbon fuel. It is part of a series of chemical compounds that are created by combinations of Hydrogen and Carbon atoms. The range includes Petrol, diesel along with Propane, Butane and many other less well known CH combinations.
Pure Propane is C3H8 and Pure Butane is C4H10 Most commercial grades of Propane and Butane contain other Hydro Carbons but will meet the requirements of EN 589 the standard for commercial LPGs.
The unburnt gas has only carbon and Hydrogen atoms so it has no water content. However when the fuel is burnt properly with air (Nitrogen and Oxygen) it basically releases the Nitrogen and recombines the H,C, & O to produce Heat, Carbon Dioxide, (CO2) and water (H2O). If the combustion is not of a good quality you can also get in addition to the items above, Carbon as soot, Carbon Monoxide, and some Nitrous Oxides.
Statement "We had two gas bottles that used to stand in the African sunlight and heat with temperatures in excess of 40 degrees C and had no issues and also did not hear of any one else having issues. They were calor gas cylinders."
This relates back to your question about bottles exploding. Calor UK state that LPG should not be stored at temperatures over 50C. As you are well aware the temperature of something standing in direct sunlight can become much hotter than the ambient air temperature, so my guess is that the bottles were easily at or above 50C. When you say you had no issues, if you had any wiff of gas near the bottles, then you have an issue!
It may be that Calor use a different specification of bottle in Africa because of the higher temperatures, they may be tougher (thicker walls and heavier) to withstand the increased pressures, but I am only guessing here.
Gas bottles should be shaded from direct sunlight
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