Engine death at 94000

Hello! On my Volvo S40 2,4 last Saturday a conrod broke down and hit me through the engine block. Through the resulting hole in the engine it caught fire. I then (stupidly) extinguished this fire. Now the learned, what is the cause. I had an LPG gas system installed at the KM stand of 89000. Until this time the engine ran flawlessly. Oil consumption was not a topic at all. However, the engine damage was caused by oil shortages. But I had not checked the oil 400 KM before and it was at the maximum level. On Friday last week the car was to adjust the gas system at the company Oecotec in Lengerich. After that the car ran perfectly, at least 350 KM. Then it came to the said damage. Would be grateful about your opinions, or tips, since I do not want to stay at the expense of the new engine (7000 €). Greeting Bernd