Other Vacuum degassing is the only way to go

Cibb said:

I pull my hose connection so the the back flow comes from straight air instead. It isn't something I like doing though. I'm considering a check valve or where it will pull air though a filter. .

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sour_grapes said:

Actually, glass carboys are quite strong. I have evacuated them effectively as low as you can go, to no ill effect. (I am a vacuum guy.)

Personally, I do not favor using oil-sealed pumps on wine, due to not wanting backstreamed oil vapors in my wine, but whatever floats your boat!

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sour_grapes said:

Actually, no, I was not talking about the oil mist that comes from the exhaust port. "Backstreaming" is the effect of oil migrating away from the inlet port of the pump, towards the carboy. You may not think this can happen, but it can indeed happen at low pressures. Think about it: the molecules, including oil molecules, don't know which direction the pump is. They just bounce around inside the tube; the molecules are more likely to wind up at the pump side than the carboy side because the pump keeps removing molecules from the pump side of the tube. However, some of them, including oil molecules, may bounce their way all the way to the carboy end.

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sour_grapes said:

Actually, no, I was not talking about the oil mist that comes from the exhaust port. "Backstreaming" is the effect of oil migrating away from the inlet port of the pump, towards the carboy. You may not think this can happen, but it can indeed happen at low pressures. Think about it: the molecules, including oil molecules, don't know which direction the pump is. They just bounce around inside the tube; the molecules are more likely to wind up at the pump side than the carboy side because the pump keeps removing molecules from the pump side of the tube. However, some of them, including oil molecules, may bounce their way all the way to the carboy end.

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Johnd said:

I don't doubt the scienctific theory at all, just doubt that it'll occur in practice, when all of the variables are considered. Said confused molecule would have to travel through the 3 + feet of tubing, a check valve, and a catch reservoir, get through a tiny hole in the reservoir, back into and through another 3' of tubing, and into the carboy.

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Johnd said:

I don't doubt the scienctific theory at all, just doubt that it'll occur in practice, when all of the variables are considered. Said confused molecule would have to travel through the 3 + feet of tubing, a check valve, and a catch reservoir, get through a tiny hole in the reservoir, back into and through another 3' of tubing, and into the carboy. I get that while the max vacuum is in place, the valve is open and there's little flow direction, but that is an instantaneous scenario, as gas coming out of solution on the other end quickly shuts the check valve as soon as the pump is stopped. After doing this hundreds of time, I just have never had any indication of this occurring.

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sour_grapes said:

You are correct that the factors you cite work to your advantage to lower the risk of backstreaming. I am glad it has worked out for you so far. If you're happy with your approach, I'm happy. As I said in my original post -- whatever floats your boat!

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