Originally Posted by onehundred80
Definition - Vacuum is the absence of matter.
Nature abhors a vacuum or any differential pressures that it can balance it if at all possible. The air/fuel mix enters the cylinder in response to the differing pressures inside the cylinder and the manifold. There would never be a true vacuum inside the cylinder, just a substantial difference in pressure between it and the manifold.
True vacuums are impossible to achieve, the closest to it that we can get is scattered air molecules floating around in a near vacuum. The last stage to produce this near vacuum, after physically pumping out most of the air is done using an oil fountain, the air molecules that remain hit the oil and stick to it, you cannot get all the air so some remains in this near vacuum.
This near vacuum is what Cd's are aluminized in to give them the mirrored look we see. The aluminum is vaporized in this near vacuum and settles on the plastic surface evenly in a very thin layer. It is some thirty odd years since I did this so the details are a little sketchy in my head.
No vacuums are associated with IC engines. Vacuum lines are lines with less air pressure in them, the less pressure there is in them the more force they can have exerted against them.
Ideally they would get to zero (nowhere near it actually) and thus allow 14 psi (approximate atmospheric pressure at sea level) to work against the diaphragms etc.
There is a gauge on my car that says "vacuum" I wonder what it means?!?
Speaking scientificaly, Vacuum is the abscence of matter. Partial vacuum is the differential between the gases in two containers. Partial vacuum is the "vacuum" of which we are speaking and is generaly expressed as simply
vacuum in engineering, not scientific circles.
We draw a "vacuum" of 20 Inches of Mercury on a package of Hot dogs. In the grocer's case there is no vacuum in the package.
We draw a "vacuum" of 12 inches on a can of Coffee. When you open it you will hear a rush. That is because, unlike the soft film surrounding the hot dogs, the hard can maintains the "vacuum" from the packaging process.
We draw 15 inches on the products we package in unsupported films. It creates the same adherance of the film to the paper much like the metalizing of plastic or in your example, the mirror. However the mirror and the film are softened by heat and the aluminium particales then actually adhere to the film or the glass. One of our products "Thermolock" does that (for packaging inside with the Hot dogs). But for the most part, the film adheres to the paper coupon by the ambient air pressure on the outside of the package.
Just like it does in a package of hot dogs. Only the package of hot dogs is drawn while stopped in a "Vacuum chamber" One of my patents does it in motion without using a closed chamber.
Like I said, I do this all day.
I can read WIKI also. Next time you want to pick the fine point post the whole WIKI explanation.
Vacuum - Wikipedia, the free encyclopedia
And for the record, the legal definiton of my related patent says "vacuum."