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Vacuum moter connection to hosing

Posted by Robert_O (Robert_O), 29 January 2004

I recall being told that if you are using a vent hose to take the air out side and to quieten the machine down, then this hose must be a larger bore than the normal extraction hose.  The reason was to prevent the vacs from heating up with the back pressure created by restricting the air outflow.

Bearing this in mind, I have a question that hopefully some one may help me to get my head around.

I won't mention any particular machine or manufacturer, but I was inspecting the inside of my machine the other day and noticed that the connection hosing coming from the vac exhaust was connected within the internal bore of the vac connector stem.

Now it seems strange to me that this would be connected up in this way, as it is clearly and unneccessarily narrowing the venting exhaust pipe.  Is there a logical reason why this would be connected in such a way, after being told the importance of not restricting the venting of the machine?

Over to some one who knows a little more about vac configurations and airflow etc.

But I think that I will be changing mine over soon if I don't hear any argument in favour of the manufacturers installation setup.


Robert Olifent
Posted by mike_halliday (mike_halliday), 29 January 2004
i would think that the back pressure is a result of air friction within the vac hose, so its not the diametre of the hose but the length the vacs have to push the expelled air.

so the internal hose set-up you saw would cause a small restriction, but as the hose leading out of the vac motor was only restricting the air for a short distance it would'nt unduley effect performance or cause overheating.

I was looking at an Extracta machine yesturday in an auction and i noticed that the vaccuum hose connector had an internall diameter of about 1 inches, so why use 1.5 hose?.

I think that to restrict  the air flow over a very short distance cannot seriously effect performace.

hope this makes sense Smiley

Posted by Robert_O (Robert_O), 29 January 2004
Thanks for that Mike, as that certainly makes sense.

However me being me, the next time the moter has to come out I will change it over to outer pipe casing connection.

It just seems better to me.

Thanks again.

Robert Olifent

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