On Sat, 27 Feb 2016 11:19:14 -0800, OFWW wrote:

On Sat, 27 Feb 2016 10:10:41 -0500, krw wrote:

On Fri, 26 Feb 2016 22:48:18 -0800, OFWW wrote:

On Fri, 26 Feb 2016 19:59:32 -0500, krw wrote:

On Thu, 25 Feb 2016 23:01:34 -0600, Leon lcb11211@swbelldotnet
wrote:

On 2/25/2016 8:00 PM, krw wrote:
On Wed, 24 Feb 2016 23:07:33 -0600, Leon lcb11211@swbelldotnet
wrote:

On 2/24/2016 9:18 PM, krw wrote:
On Wed, 24 Feb 2016 20:39:08 -0600, Leon lcb11211@swbelldotnet
wrote:

On 2/24/2016 8:06 PM, OFWW wrote:
On Wed, 24 Feb 2016 10:04:59 -0600, dpb wrote:

On 02/24/2016 1:38 AM, OFWW wrote:
...

In a vacuum strange things happen, given a spark, and a whoosh of dust
already suspended in the pipe (your cloud) and I can see things happen
that wouldn't happen in a positive pressurized pipe.

If it were a vacuum, there'd be no oxygen, hence no combustion.


At sea level the air pressure is 15PSI. Every 2" of vacuum is
equivalent to a 1 PSI drop in pressure. So at what point do you
consider a vacuum a vacuum? And how does a gasoline engine operate
when its intake manifold is in a vacuum if there was no oxygen?

Well hopefully there is no combustion inside of the manifold and having
said that, typically the fuel is combusted when it is under higher than
atmospheric pressure. And engines work better when the fuel bypasses an
intake manifold altogether and is atomized, by an injector, at the
optimum location and time inside the cylinder. BUT YES you need a
vacuum inside the manifold to draw fuel into the heads and cylinders
from a throttle body or carburetor. IIRC sometimes up to 15~30 lbs of
vacuum in the manifold at idle, considerably less during full throttle
with the butterflies fully open.

15-30lbs.?? Atmospheric pressure is only ~14psi.

Vacuum, not pressure.

Exactly the problem. You can't pull a vacuum higher than the outside
atmospheric pressure. That is, once you suck all the air out of the
room (14psi), you can't suck any more. Well, The Donald can, but...

OK, My mistake, not PSI, inches of vacuum. I was trying to recall what
the vacuum gauge on my first car indicated. I thought it was between
15~30 "inches".. apparently inches on the gauges are double actual PSI.

I questioned it because you said it and it was repeated. I didn't
know if you were talking about in.Hg, or what. Yes, PSI is half in.Hg
(though I hadn't thought of it that way) by the simple fact that
1ATM = ~14PSI = ~30"Hg.

1ATM = 14 PSI = 0" Hg

No, you've got absolute and relative pressure measurements mixed
together. 0" Hg (absolute) is a vacuum. 0" Hg relative to 1ATM is,
well, 1ATM.

No, 0 psi is absolute. Vacuum is always relevant.

No, it is not. Your tire gauge will read 0PSI when the absolute
pressure is 14PSI. The tire gauge is a *relative* measurement but
this is understood by its context.

Atmosphere

Unit

The standard atmosphere (symbol: atm) is a unit of pressure defined as
101325 Pa (1.01325 bar). It is sometimes used as a reference or
standard pressure. In 1954 the 10th Conférence Générale des Poids et
Mesures (CGPM) adopted standard atmosphere for general use and
affirmed its definition of being precisely equal to 1,013,250 dynes
per square centimetre (101325 Pa).

All irrelevant.

Therefore 1 atm is equal to 14.69595 psi

....either relative or absolute.

There is no such thing as a vacuum, per se' it is always a relative
measurement.

Nonsense.

At 250,000 feet above sea level it is 0 PSI Absolute. Imperial
measurements.

OK, but the sky is blue.

Using a moisture indicator on any wood, it would register "0"

Microns is also used in measurement of a vacuum to tell when certain
physical properties are no longer there.

What *are* you jabbering about now?