Go look up how a diesel engine works
https://www.explainthatstuff.com/diesel-engines.html , even gas engines can diesel when they have too much carbon build up.
https://axleaddict.com/auto-repair/Why-My-Engine-Keeps-Running .
Here is an quote from the article on diesel engines I linked, "in a
diesel engine, the air is compressed by anything from 14 to 25 times." 1
bar is equal to 100,000 Pascals, which is close approximately to atmospheric pressure. So if 1 bar is atmospheric pressure, these air guns are holding 250 to 300 bar or 250 to 300x atmospheric pressure. Lets do the math, 300/25 =12 in other words 12x more compression than the 25x compression in a diesel engine. Over kill to cause a diesel explosion if their is an adequate amount of oil in the plenum.
In this thread the OP ask how much do I need to compress air to raise the temp from 20 c to 100C,
https://www.physicsforums.com/threads/temperature-of-compressed-air.341969/ . The answer at the end of the thread is "So you would need to increase pressure to 2,513 psi if you started from atmospheric pressure." Wait for it, 300 bar is equal to 4351 PSI. BTW 100C is 212 F.
If the initial air temperature is 20°C and it is compressed from 1 bar to 300 bar, the approximate final temperature would be around 606.3°C. Final temperature of 606.3°C, when converted to Fahrenheit, is around 1123.34°F. More than ideal conditions to cause a diesel explosion if enough oil is present and vaporized.
So when you fire and empty the plenum and it suddenly fills there is an increase in temperature. I know that we are not dumping the plenum all the way down to 1 bar when we fire and whatever your reg is set to is the new fill pressure but you get the point. Lets consider the scenario in which this happened. Cold conditions(freezing), perhaps the valve that is supposed to open on the regulator froze shut for a second and allowed the plenum to fully discharge. Then the pressure of the tank over comes the stuck valve and opens. You would have a sudden and large temperature spike and if oil is present and now dispersed into to tiny droplets you would have an internal explosion inside of the plenum.
We have to consider all possibilities, I don't own a Edgun leshiy 2. Nor will I ever unless someone donates one to me or I find a good deal, it's just out of my price range. If someone sent me one or offered me one I would take it gladly without fear of it exploding in my face.
There is the a saying "a chain is only as strong as it's weakest link." In air guns I've seen O-rings and Poppet valves fail and consider these as the weakest links in these air gun designs. Part of me wonders if there is a way to redesign these air guns to use something else with less failure rates as O-rings, but I rather have an O-ring fail than have a new method that is so much better that the next weakest link becomes actual plenum or air tank. So in a sense the O-rings are the fuse that prevents bigger catastrophic failures.
