A few thoughts. . .based not on marine experience, but based upon experience in the petrochemical industry. I think it is relevant here. Not sure how these remarks play for a marine closed loop system. . as I am unfamiliar with what materials are used. Is it mostly stainless steel, bronze and plastic?
First. . water is pretty corrosive. It may be necessary for life, but for carbon steel systems (like marine engines). . the stuff is evil. Especially with oxygen present. And guess what. . .water has PLENTY of oxygen in it. Take a pot of water, and a small fish can live in that water from some time.
So. . . I am not surprised by Dennis's experience of rust in an engine that sat for two monthes.
2nd. It doesn't matter if a system is flooded or allowed to "drain". Either way. .there is a lot of water and alot of oxygen around. My experience says if you simply "drain" a system of water. . you will get lots of rust. How does my industry stop rust? After draining a system, we flood the system with pure nitrogen. Even if the system is usually dry, if we want to *preserve* a system. . you put it in a nitrogen atmosphere.
3rd. For "closed loop cooling systems" , there are corrosion inhibiitors in the fluid. For open systems, like steam boilers, water chemistry -including dissolved oxygen- is carefully monitored and controlled. (We use steam stripping to drop the oxygen content, and then small amounts of chemicals to eliminate the rest of the oxygen)
4th: Rust type corrossion is a time based thing. Engines do not last forever. The rusting process will happen all year long. However. . . I have to believe if for 50% of the time (November to April) the system is immersed in a fluid full of corrossion inhibitors . . .I have to believe that the system will last longer. Of course. . it may be that the engine will wear out due to use before it corrodes even if you don't use inhibitors. . .but . . . .
ok. . . I am back off to the bilge.
First. . water is pretty corrosive. It may be necessary for life, but for carbon steel systems (like marine engines). . the stuff is evil. Especially with oxygen present. And guess what. . .water has PLENTY of oxygen in it. Take a pot of water, and a small fish can live in that water from some time.
So. . . I am not surprised by Dennis's experience of rust in an engine that sat for two monthes.
2nd. It doesn't matter if a system is flooded or allowed to "drain". Either way. .there is a lot of water and alot of oxygen around. My experience says if you simply "drain" a system of water. . you will get lots of rust. How does my industry stop rust? After draining a system, we flood the system with pure nitrogen. Even if the system is usually dry, if we want to *preserve* a system. . you put it in a nitrogen atmosphere.
3rd. For "closed loop cooling systems" , there are corrosion inhibiitors in the fluid. For open systems, like steam boilers, water chemistry -including dissolved oxygen- is carefully monitored and controlled. (We use steam stripping to drop the oxygen content, and then small amounts of chemicals to eliminate the rest of the oxygen)
4th: Rust type corrossion is a time based thing. Engines do not last forever. The rusting process will happen all year long. However. . . I have to believe if for 50% of the time (November to April) the system is immersed in a fluid full of corrossion inhibitors . . .I have to believe that the system will last longer. Of course. . it may be that the engine will wear out due to use before it corrodes even if you don't use inhibitors. . .but . . . .
ok. . . I am back off to the bilge.
