causes of aeration
Hi PPRUNE. Non-pilot,non-anorak, first post. I've been reading the Rumours board intermittently for years so I realise that taking the risk of posting on any technical issue is foolhardy, but here goes. I offer it only for what it is.
Many years ago I was involved in an operation that required pumping lots of water from a river, using a diesel engine (250hp) driving a 4 inch Ajax centrifugal pump. One day I replaced the cage which was fitted to the (non-return) foot-valve - which was intended to prevent large stones being drawn into the suction line. It was badly damaged, so I placed a stainless steel mesh directly across the valve opening (ie "2d" replacement for a "3d" predecessor).
To cut a long story short, we repeatedly encountered delivery failure after about an hour of operation. When checked, we discovered that the pump was partially full of air and consequently was cavitating. I assumed that this was due to a leak on the suction side and repeatedly refitted the suction hose (an 8", heavy, beast) with added sealant and many clamps.
Then it dawned on me to take into account the recent changes to the foot-valve protection. Clearly the restriction to the flow was causing air to gradually come out of solution, hence the eventual cavitation. After replacing the grid with a fabricated box of the same material, the problem vanished.
I have read a lot of the preceding thread. I understand a little of it - in very broad terms anyway. I don't recall if anyone has implied the cause of the "aeration" which has been referred to, except in relation to the possibility of leaky seals on the lp side. But I kept being reminded of my own experience described above. It would only be relevant if there is indeed any dissolved gas/air in jet fuel etc etc, about which I have absolutely no idea.