Correcting a common misconception about vacuum pumps mechanism of action - and making the case why sleeved pumping really does prevent edema.

Correcting a common misconception about vacuum pumps mechanism of action - and making the case why sleeved pumping really does prevent edema.

The following is a re-post of an article I wrote on r/gettingbigger: 

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Yesterday I posted about “sleeved pumping” using silicone toe shields worn on the shaft while pumping, in order to prevent edema from becoming too pronounced. Several people commented about how this was basically the same as just pumping at lower pressure. Their reasoning was as follows, and I’m trying to do it justice here by strong manning the case:


Let’s say the sleeves will exert a positive inward force equivalent to +3 inches of mercury (the + sign indicating it pushes inward on the penis), and let’s say you pump at -12 inches of mercury. The vacuum will be pulling the penis outward with a force of -12, but the sleeves will push in with + 3, and -12 + 3 = -9, so what you will get is an effect identical to simply pumping at a vacuum pressure of -9 inches of mercury in the first place.


If you want to read the comments, the post I made about using silicone toe shields for sleeved pumping is here: https://www.reddit.com/r/gettingbigger/comments/1aprtyc/pumping_with_silicone_toe_shields_to_minimise/?utm_source=share&utm_medium=web2x&context=3


At a first glance, I can see how this line of reasoning seems convincing. However, it is deeply flawed, since it’s based on a very common misconception about physics. It’s this misconception I will attempt to correct.


First, you need to understand that the atmospheric pressure is considerable, and that we just don’t notice it because we live in it and have the same internal pressure. You know the OceanGate submarine Titan that imploded at a depth of 3500 metres? Yeah, fish swim around at that depth, and they do just fine. This is because they’re adapted and their internal pressure matches the surrounding water.


At sea level, the atmospheric air pressure is around 101.3 kPa (kilopascals), or about 30 inches of mercury in a pumping context. How much is this? Well, in pounds per square inch (psi), it’s 14.65, and a normal size man has a skin surface of around 2900 square inches (1.9 square metres), so the total force on your skin is about 43.000 pounds. Yes, 43 thousand pounds of force. But we don’t feel it, because we have the same internal pressure pushing out.


If you don’t believe me, watch this video where they heat up the air (steam) inside an oil drum at atmospheric pressure, cap it off, then rapidly cool the air inside to cause a partial vacuum.The pressure differential is large enough to crush the oil drum like you would crush a can in your fist. This is the air pressure we have around us all the time…




When our heart beats, this further increases arterial blood pressure (normally around 4.7 inches of mercury, though it’s often expressed as 120 mmhg in a medical context - I just convert to “pumping pressures” here to help you understand better).


Second, you need to understand that a partial vacuum does not magically “pull on” the skin of the penis. Air can exert a positive pressure on a surface - it can’t pull on a surface. No, what happens when you use a partial vacuum inside a pump cylinder, is that it creates a pressure differential between your inside pressure (atmospheric pressure + arterial pressure) and the much lower pressure in the cylinder. It’s literally the atmosphere and your heart which inflates your penis when you pump - i.e. internal pressure, working from the inside of the penis and outward - which causes it to inflate into the space with lower pressure around it. If you were to wring a balloon over the entrance of the vacuum cylinder and pump a vacuum, the balloon would not be “pulled into” the cylinder by the vacuum, it would be “pushed in” by the external pressure. This is an important conceptual distinction.


So when you add a sleeve which pushes inward on your skin while pumping, yes it does diminish how much pressure differential the skin will experience, but mainly it serves to prevent fluid from accumulating in the areolar space between the superficial and deep fascia of your penis. The tunica albuginea is expanded by the pressure inside you, which, granted, will be restricted by the presence of the silicone sleeve, but if you just compensate by using a stronger pressure differential it can still expand to supraphysiological proportions, which is what we want. The back-pressure from the sleeve just acts as a resistance against fluid build-up. Basically, it acts as a layer of harder skin, more resistant to edema.


Your tunica is being pushed out by your internal 14.65 + 2.3 PSI = 16.95 PSI pressure, but resisted by the vacuum and the sleeve, both pushing inward on your penis. Yes, the air pressure in the cylinder is pushing inward on your penis, not pulling outward. It’s just that it’s a lower amount of pressure pushing inward on that part of your body, than on other parts.


Just knowing this makes it much easier to understand why the prima facie objections presented against the efficacy of sleeved pumping are moot, because they are built on an erroneous intuition about what a vacuum pump fundamentally does. It doesn’t pull, it just allows your internal pressure to act with less outside resistance.

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