How Backpressure Is Create By Static Lift

'...The question is quiet clear from the title. Let us suppose in a condensate line (of steam for instance) backpressure is generated because of the vapour pressure of noncondensables...'

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No, the question is not 'quite clear' from the title. Unfortunately, what followed in the post made it even less clear.

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While it feels good to do a good job writing something clear and concise, skipping right away to congratulating yourself for such clear expression is a bit pompous.

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Congratulating yourself for clear expression when that is not actually the case, takes it to a completely different level.

Why is this ot ???

I corrected that...

Try blowing water up a 3-meter tall tube, and you will see that it requires pressure.

The concept is simple. Don't use the steam pressure in the heater to lift the condensate into the return main; use a pump instead.

In my life previous to becoming an engineer, I used terms like "back pressure" only to slowly come to the suspicion that this thing didn't exist. Then I went to engineering school and spent all that time never once using the term. Now this is something I only hear non-professionals and chemical engineers say.

The term I have learned to think of when someone says "back pressure" is "line loss" . . . mostly. The problem is, in my mind, the term is unspecific. In the case of the OP I think the term is being used instead of "static head."

So, I think this fellow (in his, not very clearly worded question) is asking about a steam trap (float type?) and the pressure differential across the orifice. Steam pressure on one side as the motive force and a column of condensate on the other side pushing "back" on the needle valve.

In the case of the steam trap, the size of the needle valve orifice, and the size of the float, determines the pressure differential (dp) needed to open the valve. The steam pressure must then be sufficient to overcome the static head pressure of the condensate column on the other side. If the condensate header has positive pressure, this must also be overcome.

I don't know if I have made this any more clear or not. I can only hope that I have helped. Please ask if you need additional clarification.

-A-

links please?