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The physics of force transmission in air versus water pumping

Originally Posted by dtwarren1942
I do not believe air mixes with water at these low forces. However, air does get into my cylinder while starting to form a seal and it forms a bubble at the top or bottom, depending on the direction of the cylinder. This reminds me that when I have a large air bubble in my cylinder it movies up and down the cylinder past my penis as I change directions. As the bubble moves up and down over my penis, I can not feel any change in the vacuum as it passes. Accordingly, this confirms, for me anyway, that the 5 hg pressure does not change as I switch from water to gas inside the same cylinder.

Next time I water pump, I am only going to fill the cylinder half way up with water and see if I can detect any change in pressure between the two mediums,

<snip>

This is why we recommend pumping with a gauge, dt. The penis is not reliable as a sensor of pressure/vacuum variations.

Originally Posted by Tossed Salad
One thing I’ve noticed with water pumping is that my penis doesn’t feel dehydrated like it does when I air pump so maybe there’s more to it then just simple dehydration vs hydration.

If your penis is completely surrounded by water, and you’re using tap water, which is less salty than your blood and lymph, osmotic forces are going to cause a net fluid gain into your penis. In other words, your penis should wind up more hydrated after water pumping with tap water. That was the point I was making earlier about adding salt to the water you pump with. If you add enough - to where it is saltier than your body fluids - it would tend to draw fluids out of your penis.

And if your penis is surrounded by air, and especially if that air is at lower than atmospheric pressure, I would expect there to be fluid loss from your penis, so I would not be surprised by slight dehydration.

That makes me wonder a little bit about whether that may be a part of why there’s less overall donutting after water pumping. An overall gain of fluids to the penis might comparatively reduce what would otherwise be a more localized gain of fluids just below the glans.


For Lampwick, becoming hung like a donkey was the result of a total commitment.

Originally Posted by marinera
Sparkyx, the point here is simple : as far as your penis is immersed in water, it will fight more resistance against expansion. 5 hg are pulling on your penis, but water is pushing against your penis. If there is nothing, the penis can expand; if there is air, there isn’t much force fighting expansion; if there is water, there is more force fighting expansion.

Ok man, again what your saying would be true in a sealed system, if your penis in a standard cylinder full of water with no air bubbles and no hose attached
then you are correct the water will act as a fluid solid and prevent any expansion of your penis,
But that’s no the case, if we look at the bathmate you have almost the same situation described here except the cylinder itself gets larger as the rubber bellows expand, so you have a fixed amount of water and an increase in total volume of the tube , the only thing left to expand to fill that space is the penis,
Granted some of that expansion may be fluid build up, skin being pulled in etc but every cc the tube increases in volume must be replaced with something and it cant be the water,
As long as the bellows are expanding you have a constant pull on the penis, the only difference with a standard pump is that it’s the physical pull on the handle that is effectively transmitted to the penis through the air or water and since water is effectively rigid as sparkyx said the transmission of force is more efficient.

I look forward to your response

That is a very interesting point. How does the penis expand when it is surrounded by a nearly incompressible medium?

I can understand it with the Bathmate. It may be a sealed system, but the volume is not fixed, it is dynamic due to the bellows mechanism, as capernicus1 notes. But I don’t know how the penis expands in a sealed system with a fixed volume, such as a standard cylinder and pump system. Does the expanding penis push water out of the cylinder and into the overflow cup?


For Lampwick, becoming hung like a donkey was the result of a total commitment.

My understanding is that as long as you still have air in your pump or fluid cup then you still have a vacuum force pulling on the water,

after all isn’t that what inches hg relates to , the distance a vacuum can raise a column of mercury,

I admit i’m getting to the limits of my knowledge here.

Originally Posted by capernicus1
Ok man, again what your saying would be true in a sealed system, if your penis in a standard cylinder full of water with no air bubbles and no hose attached
then you are correct the water will act as a fluid solid and prevent any expansion of your penis,
But that’s no the case, if we look at the bathmate ….


You have 5hg in a water pump, you have 5 hg in an air pump. 5hg is the force pulling. Water is not compressible. At the same force, the penis will expand more in the air pump. That’s the point I’m making.

I’ve never managed a bathmate, so I want to leave out the chance that I’m missing something, but the replies I’m getting are not elucidating anything either. At any given level of [de]pressure, you can look at your pump as a sealed system, otherwise you are not comparing the same level of force. If water leaves the pump and air is not entering, you are creating more vacuum so pulling with more force.
So you have to use more force than with air to reach the same expansion.

I’ll repeat, this is just my understanding.

Maybe a simplier way to get what I’m saying is to consider the weight of the water? 5hg are pulling : on what?

All your counter arguments are very persuasive and at this point i’m kind of stuck,

I can only say that having done both methods for many months the feeling of water pumping is very different and the expansion measured several

hours after a session is definitely better.

It would be nice to have this debate put to bed at last, is their no one who can settle it one way or the other ?

Haha, there is nothing to settle, I’m not trying to win an argument, you shouldn’t either. We should just put a cooperative effort trying to understand what is going on when pumping. Which isn’t that simple when you start considering not only the physic of the process, but the biologic reactions.

Consider this: you say

Originally Posted by capernicus1
….
I can only say that having done both methods for many months the feeling of water pumping is very different and the expansion measured several
hours after a session is definitely better.
….


well. You (we all, actually) are supposing that the larger expansion in the tube, the better. That could be not true. What’s the more frequent complain among clampers? ‘The sole area that is growing is the area under the clamp.’. The area which is not expanded when clamping. Sounds like a paradox, doesn’t it?

I have given that much thought before, if the constricted area under the clamp does indeed grow better then maybe pumping in a packed tube is the way to go for girth,

haha i’ll let you know when i get there,

Also if you are correct about water pressing on the penis in the tube and limiting expansion then that may have a similar effect and maybe water is better after all ?

AARGHH i need a good nights sleep to process all this

:)

The density of a material is defined as the mass per unit of volume. It’s a measure of how tightly the atoms of a material are packed. It has nothing to do with the hardness of the material. For example, water has a density of 1000 where as air has a density of 1.29. Accordingly, if you apply 1000/1.29 or 775.2 units of pressure/ force against a closed container of air, the density of the air at this pressure/force will equal the same density as water. In other words, air becomes just as incompressable as water when 775 units of pressure/force are applied against the air. (Pressure in this scenario is based on Pascals - newtons/area. The calculation is way above my pay grade)

Phew, I need a brake.


Last edited by dtwarren1942 : 08-19-2011 at .

Originally Posted by Lampwick
That is a very interesting point. How does the penis expand when it is surrounded by a nearly incompressible medium?

I can understand it with the Bathmate. It may be a sealed system, but the volume is not fixed, it is dynamic due to the bellows mechanism, as capernicus1 notes. But I don’t know how the penis expands in a sealed system with a fixed volume, such as a standard cylinder and pump system. Does the expanding penis push water out of the cylinder and into the overflow cup?

Obviously, the volume CANNOT be fixed. I don’t believe the penis pushes the water out, the valves on the pump prevent that. When you pump the pump, you draw more water out, lowering the vacuum level and the penis expands some more.

With air pumping, you set vacuum with a pump. The penis expands, vacuum decreases because the air is compressed. You note a drop on the gauge, and pump some more air out, and vacuum raises to what ever level you pump to.

With water pumping, you set vacuum with a pump. The penis expands and vacuum decreases because the expanding penis puts a positive pressure on the water, decreasing the measured vacuum with your pump gauge. You pump WATER OUT OF THE CYLINDER, and the vacuum is brought back up to the desired level. IF you don’t have a over flow cup it is pulled into the pump and ultimately out the air vent in the pump, likely ruining the pump. IF you have an overflow cup the water is caught in the cup, sparing the pump from damage.

There is no difference in the mechanism of water removal or air removal from the cylinder to accommodate the expansion of the penis. The only difference is water is a non compressible medium. Both ways need to pump more of the medium out of the cylinder in order to compensate for the vacuum drop due to the expansion of the penis.

With water, because it is non compressible, the penis expands or compresses due to the vacuum level. At no time have I ever used a positive pressure force with water pumping, so my penis is always expanded beyond normal atmospheric pressures. When penile expansion progresses enough for the gauge to note a decrease in vacuum levels, I pump some water out and bring it back up to 5 in hg (in my case). With electric pumping, the valve is set to pull a steady 5 in hg, so it constantly compensates for any penile expansion.

The pump uses AIR to transmit force to the water, and the water transmits the force to the penis, or more accurately, reduces atmospheric pressure on the penis, causing the internal pressure from the blood to expand the penis. Actually there is no pulling on the penis, you just remove the counter force that compresses the penis from the surface.

Its like if you see a Space movie where an Astronaut loses pressure in his Space suit, and he is exposed to the vacuum of space. His internal pressure, no longer neutralized by the external pressure of his suit, so he expands and dies from that expansion (not to mention cold and lack of O2).

This is also why I think pumping hard is more productive than soft, because the net expansive forces of reduction of external pressure plus the internal pressure is greater when there is more internal pressure (erection). Net expansive force of 5 in hg with an erection is significantly more than without an erection.

Originally Posted by marinera
You have 5hg in a water pump, you have 5 hg in an air pump. 5hg is the force pulling. Water is not compressible. At the same force, the penis will expand more in the air pump. That’s the point I’m making.

I’ve never managed a bathmate, so I want to leave out the chance that I’m missing something, but the replies I’m getting are not elucidating anything either. At any given level of [de]pressure, you can look at your pump as a sealed system, otherwise you are not comparing the same level of force. If water leaves the pump and air is not entering, you are creating more vacuum so pulling with more force.
So you have to use more force than with air to reach the same expansion.

I’ll repeat, this is just my understanding.

Just purely from experience, water will draw greater expansion (by measuring length) than air (at the same vacuum level on the gauge), and that is after compensating for the optical distortion from the water. (if you place the water filled cylinder, under water, like in a bath it negates the optical distortion.)

Again I believe its because when water is pulled out of the cylinder, the penis MUST fill that area because the water will not expand to fill it. That is not the case with air.


Last edited by sparkyx : 08-19-2011 at .

Originally Posted by sparkyx

This is also why I think pumping hard is more productive than soft, because the net expansive forces of reduction of external pressure plus the internal pressure is greater when there is more internal pressure (erection). Net expansive force of 5 in hg with an erection is significantly more than without an erection.

Seems logical. However, I have severe ED. Accordingly, I normally need to pump just to force blood into my penis in order to have an erection. When I exit the cylinder, I am engorged but I only have a 50% semi erect penis, on a good day. I don’t believe a semi is going to exert much outward pressure on the air/water, but rather the negative pressure/vacuum is what forces the blood in along with some edema as the pull of the vacuum forces the penis to expand. Still, I do notice that as time goes by, the vacuum gauge does very slowly decline and additional air needs to be pumped out to maintain the 5 hg vacuum and the longer I remain in the greater the engorgement. My theory is that the vacuum draws in more blood/ liquid which is more effective in pushing against the air in the cylinder than the normal composition of the penis.

I doubt the internal force of erection will sum with what you read on the gauge, since the gauge is measuring the negative pressure acting on the matter inside the cylinder - that would be, the force which is directed toward the walls of the cylinder.

Originally Posted by sparkyx
Just purely from experience, water will draw greater expansion (by measuring length) than air (at the same vacuum level on the gauge),…


Measuring by length. Not girth. Girth is compressed. Length is enhanced for the same reason and for the buoyancy - although this can depend by the depth of the cylinder. The total expansion, at any given pressure, will be lower in water, though. It would be like pressing with your hands on your whole shaft and a clamp at the base - you can have a bit more length, but the reduced girth will more than compensate this.

Let me ask one thing : it is easier for you to walk when submerged in water or in air? That’s it. You don’t want to transmit force, you want to subtract force.


Last edited by marinera : 08-19-2011 at .
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