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Author:
george 7941 (Canada)
On sinks without overflows, the air bubble, shown in red, blocks the flow of water down the drain. Water Column A, being considerably larger than WC B, should force the air bubble down into and out through the trap. Is the surface tension of the water surrounding the air bubble causing the water to be attached to the grid holes and thereby generating enough force to withstand the water column pressure?
If it is surface tension then soapy water will flow more freely since it has less surface tension.
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Author:
hj (AZ)
quote; Water Column A, being considerably larger than WC B, should force the air bubble down into and out through the trap.
If that were true, then there would be no problem with "double traps" because they have the same condition.
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Author:
george 7941 (Canada)
It is true that WC A generates more pressure at its base than WC B. There is some mechanism counteracting this pressure in grid drains and in double trapped drains.
Why isn't the air forced out?
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Author:
hj (AZ)
Not just there, but in any situation where air is trapped between two sources of liquids, unless there is a very great elevation distance. A coiled hose is another instance, since you cannot pour water into one end and have it come out the other if there is a loop in it. And how about heating systems, which have a pump on them, but will still stop circulating if there is an air bubble in the line? It has a lot to do with air being compressible and also lighter than water.
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Author:
bernabeu (SC)
single trap = no problemo
double trap = TWO columns of water to overcome = problemo
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