2007-08-18 02:52:35 · 5 answers · asked by scorfield 1 in Science & Mathematics ➔ Engineering
It usually refers to air. For instance, some breathing machines provide a constant flow of air into the patient's lungs when they have trouble with bronchspasms.
In the fire service, there is a positive pressure feature on our air packs that allows air to continually flow into your mask. This keeps any smoke from seeping in.
In hydraulics, it can refer to the hose that contains the fluid that is coming out of the unit. You have a positive pressure hose, fluid coming out, and a negative pressure hose, fluid going in, to complete the circle.
I hope this helps.
2007-08-18 03:08:17 · answer #1 · answered by Dawn R 3 · 0⤊ 0⤋
As you can see from these answers (all are correct) it only becomes useful to say "positive pressure" in situations where "negative" pressure (pushing the opposite way) is a possibility.
Technically, all pressure is positive. If you work with the fundamentals that the only kind there is.
Negative pressure may mean force pulling the other way, as in structural work, but it's more common that it refers to pressures below that of surrounding air. So when wind blows past a building, the wind causes a positive pressure on one side of the building and a negative pressure on the other side, relative to the barometric pressure.
2007-08-18 20:41:28 · answer #2 · answered by Firebird 7 · 0⤊ 0⤋
In structural engineering of buildings, positive pressure is defined as a force/unit area applied in the downward direction (i.e. on a roof, positive pressure acts downward). Negative pressure on a roof would act upwart (uplift).
In short, it is the direction in which the force/unit area is acting. It really is dependent upon the "what has been defined as positive". It pertains to the direction of the force/unit area.
2007-08-18 12:23:08 · answer #3 · answered by ralston3057 2 · 0⤊ 0⤋
Positive pressure is a pressure within a system that is greater than the environment that surrounds that system. Consequently if there is any leak from the positively pressured system it will ingress into the surrounding environment.
2007-08-18 13:36:25 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Positive pressure is any pressure that is over and above normal atmospheric pressure.
Positive pressure at sea level would be any pressure above 14.7 psi.
2007-08-19 01:00:52 · answer #5 · answered by gatorbait 7 · 0⤊ 0⤋