Rust vs Us

[BillL]

Originally Posted by JonJay

Your not going to impact the dew point much with an aquarium pump. What we are fighting is a high temperature, high hunidity environment that is rapidly cooling. You won't be able to catch up. What you are doing with your set up is starting the process of lowering the humidity by scavenging the water out of the system.
Now, where is that water going? Your beads lower the humidity of the air surrounding it (hangar air) and put it into your case. It then goes out the exhaust pipe and back into the same air in the hangar. Your beads can only absorb so much water out of the hangar air until they are saturated. If your hangar is a high humidity environment, the beads are not going to last as long.
I keep my hangar at 50% relative humidity. I can take a water saturated coat and it will hang dry in less than 24 hours. Since our engines are open to the air, I expect a similar result in my engine. The water isn't staying in the hangar. It is going down the drain.
So, there is a lot going on that affects what may or may not be effective, mostly the environment you store your airplane in. I believe that has the biggest impact on engine and airframe health, but, again, I am not moving to Bakersfield!

Jon, do a little experiment. Take an empty jug, milk, juice, and put some water in it. Then add 3 ft of 5/8" ID hose. Take the cap off and weigh your jug with an oz of water in it. Put the cap on with the hose and sit it in your hangar. Reweigh it every week. Note the weight reduction and report back. The scale should be able to resolve 0.1 g. This is about the same length and diameter of a breather. If yours is shorter, then choose an appropriate length.

[JonJay]

Originally Posted by BillL

Jon, do a little experiment. Take an empty jug, milk, juice, and put some water in it. Then add 3 ft of 5/8" ID hose. Take the cap off and weigh your jug with an oz of water in it. Put the cap on with the hose and sit it in your hangar. Reweigh it every week. Note the weight reduction and report back. The scale should be able to resolve 0.1 g. This is about the same length and diameter of a breather. If yours is shorter, then choose an appropriate length.

Point well taken Bill.

[JonJay]

Sorry, I was in a hurry. There might be a valve or two open along with the breather and the surface area exposed might be a bit more, but again, your right. It won't dry out like my coat example.
I do think it is important for those considering what to do, if anything, that eventually the inside of the engine will normalize with its environment. It will take on the same relative humidity if it is left alone. If your going to use a dehumidifier on the engine, I would use the type that can dispose the water outside of the hangar and keep it hooked up all the time unless your hangar is itself a low humidity environment or there is concern about something else.

Fun discussion. Not sure it is resolving anything as I still say "fly it like you stole it" is the best corrosion protection you can find.

[Mike S]

Originally Posted by erich weaver

So then how fast DOES oil drain off parts?

Pretty sure Professor Horton has done empirical testing on this------bit of searching may be worthwhile.

[hevansrv7a]

There have been a few assertions that are, I think, meant to suggest that either I'm wrong about how (or how well) the dehumidifier works or even if there is a need. Most or all of those assertions either misunderstand or worse.

First, as to the content of the vapors inside the engine at shutdown, they are almost certainly the same as the exhaust gas since they come from exactly the same source. There may not be much in the way of quantity but there is provably a non-trivial quantity of water in vapor form in that saturated vapor. I have seen water droplets inside an engine.

If you think that 50% RH is good enough that's your prerogative but for me, if it's 50% at noon and it gets cold at night then am I still safe? Here is a dewpoint calculator.
http://www.calculator.net/dew-point-...y=99&x=49&y=10

Here is a readable source for how much actual water can be held in vapor form in suspension.
http://hyperphysics.phy-astr.gsu.edu...ic/relhum.html
and
http://www.engineeringtoolbox.com/mo...air-d_281.html
Notice in this one how the curve goes almost vertical at about 150 F.

The kind I use pumps DRY air into the engine. In a reasonable period of time the vapor and even the liquid water inside the engine will necessarily evaporate. This was proven by the indicator beads that came with my engine which are as far as I can tell exactly the same as the indicator beads in my device. The device came with a second bottle. I use one and dry the other's contents then swap them when the blue beads begin to look less bright. I don't even wait for the pink to show. It is simply not relevant what happens to the air that is pushed out of the engine and treating an open environment as if it were a close one is really way off point. The device is designed to take in moist air and pump out dry air and to eventually need to have the medium, the beads, dried out so they can be re-used. The colored beads indicate the status of the beads along this continuum. There is nothing complicated nor difficult about this.

So my summary for now is:
1. the changing color of the beads proves it works or is working.
2. the change in color inside the plugs that came with my engine proved the need even before I operated it.
3. a fish tank pump is all you need because there is some back pressure and once you have dry air inside the engine you only have to maintain a slight positive pressure. The pump's output is adjustable and can easily be checked with a wet finger.
4. while drying the air inside the engine need not be the only approach, it is certainly one that a reasonable person would use given the low cost and high efficacy. A low RH hangar is good for everything in the hangar so it's desirable but not necessarily sufficient. Flying your airplane is good but it is beyond debate that each time you do it, there is a repeat of the very high RH vapor inside the engine at shutdown. If you fly it often enough then there will always be oil film protecting it. Do you know for sure either how often that is or when, for sure, you will fly it again?

[JonJay]

I think your system will work fine, in the right environment.
50% humidity will not promote rust in machinery in storage at 70deg. F.
You will be fine at night. Your engine, in storage, is the same temperature as the surrounding air. Unless you are in an un-insulated hangar or outside, you shouldn't see the temperature differential. As your temp drops, so does the dew point at 50% RH. If you don't dehumidify in an insulated hangar conditions can exist that would cause dew. I've seen it in every hangar I have owned. The dehumidifier prevents this.
Flying monthly is like an olds wives tale. Where I live, it has worked well for me to keep engine and airplane healthy. If I lived in the Southeast, at the coast, perhaps not. I don't think there is any imperial data, just long term observations.
Perhaps the ideal would be to dehumidify the hangar and use a dehydrator system after flight for your engine.
Forun discussions often evolve through seemingly argumentive tracts. It is just a discussion and nobody is picking on you personally. Fun discussion.