The Physics of Water Pumping

Do you ever find it difficult to maintain full erection in the tube? I seem to struggle with this. I’m not sure how long you are staying in for your set (I’m doing one set, either 20 or 30 minutes), but have to have some type of visual/auditory stimulation to regain or keep an erection in the tube.

How much bigger should one choose a cylinder for water pumping compared to air pumping?

Good question. The only thing I can think of is that you need a better base seal with a water pump so you do not get water all over the place. Given that you could probably get by with a larger cylinder as the only downside of a larger cylinder is the risk of sucking your nuts in and the seal should help stop this.

My air pump cylinder is a simple Leluv flanged unit whereas my water pump cylinder is a non flanged one from Mr Fantastic which comes with a substantial silicone sealing ring which grips the base of the penis inside the cylinder. I also use hot water which warms my penis during the pump session so a larger cylinder would help warm more.

Austfred

So, how much in diameter does your cylinder for water pumping differ from your other cylinder which you use for air pumping?

It doesn’t need to be much. Just big enough to have some water between your dick and the walls of the cylinder. I like mine a bit tighter because the water heats up faster when there is less of it in there.

I’m a bit over 5.5 in circumference, according to that I would choose a 2” cylinder for air pumping. G263, would you recommend for water pumping 2.25, 2.5 or something bigger?

I’d use the 2”. I’m over 5.5” and still use a 2”. That still gives you 3/4” to expand.

My air pump cyl is 2” and my water pump cyl is 54 mm (2 1/8” approx) but I think I need a larger one as I pack it up to the glans after a few mins pumping. My MSEG is 5.5”

However I consider the main problem with too big a cylinder is nuts being sucked in. I have found if I wear a scrotum ring this is less of an issue so now I would buy larger cylinders next time for both air and water pumping. The only reason for going for a smaller diameter then is if you want to focus on length rather than girth. That applies to both air and water pumping.

Austfred

Thanks

Just to be clear, if you are not packing the cylinder then it fits just fine. Unless you’re using one that is way too large. Say for example your girth is 5.75 and you expand to 6” in a 2” tube, that is not an issue. As long as you have some room to expand, and it’s not too much room you’ll be fine. That’s my opinion on the matter.

I get to about 6” girth in a 2” tube that I use for water pumping. It’s not an issue. Water doesn’t care how much of it is there for it have the alleged effect.

Wish to thank all of your contributions.
Which tube should I start with?
My goal is to get him thicker.

There are eight different inner diameters from
36 mm. (Circumference 11.31) this is just too small
42 (13.19) the same applies to this
50 (15.71) think this also is too small
Which of these five to choose from?
A. 54 (16.96)
B. 60 (18.85)
D. 66 (20.73)
E. 70 (21.99)
F. 80 (25.13)
Should I start with A. & Work my way up to the tubes until he fills up every tube in girth during a session, or as a time period that he increases in circumference.

On the inner length available to choose from:
190 mm. This is just too small
210 the same applies to this
230
250
280

My EC circumference is 15.5 cm and 21.5 cm EC BPEL?
In the flaccid circumference of 13.5 cm. Length 14 cm.

joxra, here is the best size guide: Selecting Your Cylinder Size

Water is more or less incompressible. At the pressures at which these pumps work we can consider water to be perfectly incompressible. In which case, how do water pumps generate a pressure differential without any change in volume (this is what it means to be incompressible)? In fact, pumps like the Bathmate use water as a means to transmit forces only. The force is generated by the flexible surround at the base of the tube which you compress to create the partial vacuum. In effect, the flexible (rubber?) base is playing a similar role to air in an air pump. It is the flexible base that is compressible and generates the suction forces. The water simply transmits these forces evenly to your penis. As such, there should be no difference regarding edema/fluid build-up between water and air pumps. All the matters is the pressure difference and duration of pumping. Issues such as ‘mean-free-path’ are an irrelevant side-issue here, that only help to explain the phenomenon of compressibility. Like-for-like, water and air pumps should produce the same effects, except for the small pressure profile caused by variation of water pressure with depth, which for our purposes can largely be neglected. Indeed, if the tube is held horizontally instead of vertically, there will be almost no gravity-induced pressure profile effect at all.

The main advantage of a water pump is the use of (presumably) warm water, which will help to keep tissues moist and warm. However, this, I am quite sure, is largely irrelevant compared with the disadvantages of water pumps, or particularly the Bathmate. The Bathmate has two issues which to my mind make it unsuitable for serious use - is see it more as a novelty item. First, any proper pump should have both a pressure gauge and a quick-release valve. The Bathmate X-series has neither, which to me is a serious problem. When using pumps safely it is really important to know what pressure you are subjecting your unit to. It is also important to be able to release the pressure quickly, if needed. With the Bathmate you have no way of knowing what pressures you are using, and releasing the pressure is awkward and often not very quick. Indeed, if you like to ‘pack’ a pump with your penis, you are essentially trapping the partial vacuum in the tube. This will make pressure release much more difficult without a quick release valve.

In short, there should be no real difference between air and water pumps at like-for-like pressures. Serious users should look for pumps with gauges and quick release valves, which rules out water pumps like the Bathmate.

Thanks for the input, and thanks to all the knowledgeable users that contributed here, was a great read and took me 2 hours to go through it and take notes.
So is it a fact that water being denser than air doesnt play a role in the empirically, general and reproducible observed effect that it produces less edema than air pumping?

-What would happen if we used denser liquids like water + Polyethylene glycol 400, or maybe even denser fluids? After all you can always reuse the same fluid so price would not be an objection.

-How would adding salt in a slightly higher osmotic concentration (Physiological is 280-320 mOsm, I.e. 0.9% NaCl) than the bodily fluids affect fluid build up?
I would educatedly guess or theorise that it would perhaps help bring out the fluid buildup thus would be a positive effect. You would ideally need an osmometer (could use de-shelled chicken eggs), table salt and a gram scale to make your calibrations, etc.

-Lastly, perhaps adding liquid DMSO to the water that will go into the pump cylinder will have a greater effect, its something thats worth a try.

Thanks to all!

Just started air pumping for the first time and even at 3/4hg it just feels waaay different to me. The feeling of pressure is different and it pulls me in a differdnt way.