Re: How hard can a human suck?


john.midgley@xxxxxxxxxxx wrote:
Hi

Difficult to think of a short title that doesn't sound... odd. However;

What level/extent/degree of vacuum is it possible to create by sucking
a tube? Try googling for any combination of relevant words in that
question, and see how much luck you have.

Specifically, I'm proposing to use a switch operated by a vacuum, by
mouth. The action might need to be repeated dozens of times, so needing
to suck so hard that the inside of your mouth bleeds wouldn't be good.

The switch I like the look of is on RS Components' website, stock
number 317-948. The summary is:

# Rating: Pressure 150mm(6in) WG to 1bar (14.7psi)
# Vacuum:
# 150mm (6in)WG to 670mbar (9.8psi)
# Factory preset to 9in WG pressure. External screw adjustment included
# Differential pressure preset to min 0.9psi +10

I'd be very grateful if anyone could give me an answer to the question
in the title, or give me a go/no go on this switch (or any other in
RS's stock!)

My recollection is about a tenth of an atmosphere or about 76 mbar or
about 1.4 psi. That is, you can reduce the pressure from 14 psi to
about 12.6 psi.
It ain't much.

Here's a way to test it, by the way:
Atmospheric pressure can raise a column of water about 400 inches.
Try lowering a lucite tube into a bucket of water and see how high you
can raise the column of water. An inner diamter of a cm or so is fine,
but it doesn't matter, really (why?).

PD

.

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