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# Pump vaccum expressed as weight

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## Pump vaccum expressed as weight

I wasn’t sure how to title this thread. What I’m wondering is if there are any technical bods out there that can show me how to calculate what a given Hg might roughly equate to in lbs.

I realize that there might be no absolute answer for this since it’s a whole different set of variables, but I thought that if vacuum is negative Hg/Bar pressure, then that could correlate somehow to lb/Kg or something I can more easily understand for a given surface area.

For example: If 5Hg on a 6x5 penis =~5-8lbs or similar? Or am I compaing chalk with cheese?

Regards

Shiver

I’ll try. But first, I need to say that they’re not exactly comparable. Vacuum pulls equally on every surface of the penis, whereas hanging simply pulls on the length.

In principle, the force exerted on the penis by a vacuum equals the pressure (lbs/in^2) times the area (in square inches) of the penis normal to the direction of interest.

For instance, a penis with a circular transverse cross-section of diameter “D” will be subjected to a length-stretching force of pressure “P” times this area, or P*PI*(D/2)^2.

I need to run now, so maybe somebody else can finish. The important thing is to use the correct units. I’ll try to come back later.

Let me see if I got this:

Assuming the penis were a flat ended cylinder, and we were measuring logitudinal forces only;

Girth is 5.5”
Diameter= 5.5”/PI =1.75”
So Area = PI*(1.75/2)*(1.75/2) =2.40”

Am I okay so far?

And if Hg is 5 (is 5 Hg = 5 Inches?) then 5*2.40=12lbs?

Or PI*(1.75/2)*(1.75/2)=12.02lbs

That seems higher than I was expecting, especially since the actual frontal area would be greater than the example. That’s kind of scary :eek:

Your units are all screwed up. That is 5 inches of mercury and I don’t think inches of mercury times square inches equals pounds.

I’m back. To convert mm Hg to PSI, multiply by 0.0193.

Your calculation of area looks correct. Assuming my formula above is correct, the stretching force in pounds exerted on your penis by each mm Hg would be (drum roll):

Pressure * Area = (0.0193 lbs./In^2) * (2.4 In^2) = 0.046 lbs.

At 5 mm Hg, pressure would be about 0.23 lbs. Pretty wimpy.

If your gauge is calibrated in inches Hg, multiply the mm Hg numbers by 25.4 mm/inch. In this case, 5 in Hg would correspond to about 5.88 lbs. That’s more like it.

By the way, this calculation has some interesting implications. Against normal intuition, the equation suggests that fatter dicks will be pulled harder at any given pressure than thinner dicks. In fact, the difference is rather dramatic, since pulling force goes up as the square of penile diameter. This fact, if true, may help to explain why some pumpers at TP don’t embrace the “length first, then girth” approach to PE. From the equation, fatter “rubber bands” are stretched in a pump with proportionally greater force, essentially making girth irrelevant. On the other hand, you may not be able to get much stretching force out of a pump at safe pressures, so you’re probably better off hanging if your goal is length.

Another thing to keep in mind is that the pulling force within a pump is actually exerted at the skin of the penis, mostly at the glans. The force is transmitted downwardly along the length of the penis, but may not be entirely transmitted to the tunica. There’s probably some loss due to the fact that the skin and the glans are not perfectly adhered to the tunica. For example, lymph can flow in to equalize the pressure, reducing the tension on the tunica. The effect is probably small, however.

Where is Mr Wizard when you need him.

Couldn’t you tell I was interviewing for that position?

Impressive analysis. I love mathemeticians and physicists. Glad I’m neither.

Originally Posted by ModestoMan
By the way, this calculation has some interesting implications. Against normal intuition, the equation suggests that fatter dicks will be pulled harder at any given pressure than thinner dicks. In fact, the difference is rather dramatic, since pulling force goes up as the square of penile diameter. This fact, if true, may help to explain why some pumpers at TP don’t embrace the “length first, then girth” approach to PE. From the equation, fatter “rubber bands” are stretched in a pump with proportionally greater force, essentially making girth irrelevant. On the other hand, you may not be able to get much stretching force out of a pump at safe pressures, so you’re probably better off hanging if your goal is length.

Another thing to keep in mind is that the pulling force within a pump is actually exerted at the skin of the penis, mostly at the glans. The force is transmitted downwardly along the length of the penis, but may not be entirely transmitted to the tunica. There’s probably some loss due to the fact that the skin and the glans are not perfectly adhered to the tunica. For example, lymph can flow in to equalize the pressure, reducing the tension on the tunica. The effect is probably small, however.

Excellent info Medesto! This opens up a whole new area of investigation for me. I’ve never done hanging, but am looking at ways to keep a modest to medium stretch for longer durations (20-40 mins) whilst keeping the penis vivibly exposed. The Bib is focusses way too much on the ligs for my liking, and I’d like to find a way to get gains without dramatically changing my LOT. That’s probably making my goals much tougher than they need to be but ultimately I want to sculpt my penis. Putting a slight upward curve and having a high erection angle on an 8x6 or 9x7 seems much more appealing than a huge trout hanging between my legs.

It is for the above reason that condom pumping is of special interest to me, but the best asthetic results I’ve had with that are by using very modest vacuum which while nice for a ‘friday night effect’ are not going to hack it for the forces needed for tunica stretch.

I’ll check out the readings on my gauge tonight then do the calcs, but it’s off to work for now.

Modesto’s manifesto!

Shiver,

Could you point to a good thread that explains condom pumping, or just explain what the basics are? I tried looking this up the other day, but couldn’t really it out.

Cheers!

I’m really waiting for somebody to tell me I’m full of sh*t! Maybe an engineer should check my work.

Another interesting consequence of the theory: People with curved dicks benefit from greater lengthwise stretching. Think about it. Look down the length of your erect penis. The “circle” you see is actually larger that the circle created by your girth alone. The area of all of this bigger circle is available for lengthwise pulling inside the cylinder.

Last edited by ModestoMan : 08-27-2005 at .

So maybe we need a clamp on donut/plunger in a 10” diameter tube? :D

Originally Posted by ModestoMan
Shiver,

Could you point to a good thread that explains condom pumping, or just explain what the basics are? I tried looking this up the other day, but couldn’t really it out.

Cheers!

I take it you’ve read the condom pumping thread? I’d be happy to contribute anything I can, but as Avocet has stated elsewhere, that should really be confined to the condom pumping thread.

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