Hanging/extender weight equivalence” table for longitudinal force when pumping (packed)
This blog post was from Karl Wikman's PE blog. He is a moderator on the subreddit TSoPE
His blog can be found here.
And his reddit can be found here.
This is a technical one…
I have been using a handy little calculator to find the longitudinal force experienced by the penis in a (packed) cylinder when doing flaccid length-pumping.
https://www.desmos.com/calculator/e5nezsvhvi?lang=sv-SE
Today, I got tired of using that calculator, and decided to just go ahead and make a table once and for all:
Cylinder diameter is on the y-axis. Pressure is on the x-axis. The force is expressed in “pounds of force” for easy comparison to hanging or extending.
Note 1: If you use plenty of slick lube, less than 5% will be lost. If you use minimal lube, the friction coefficient will cause 5–10% of the force to be lost, so subtract a little. This table is only meant to give you a decent ballpark number within a few % of error margin.
Note 2: This assumes you are packing the cylinder, which is what is recommended when doing PB-style high pressure rapid interval flaccid length pumping (with or without vibration).
Note 3: If you are using an oversized cylinder, you will of course experience a significant longitudinal force as well, but to calculate it you will need to use your erect girth divided by 3.14 as the diameter. Perhaps add about 10% since you will get a little larger than your erect girth. For instance, I am 5.9" girth, which divided by 3.14 is 1.88" and I would round that up by 10% (i.e. adding 0.18) which is 2.06, and I’d look at the table for a 2.0" cylinder instead of the 1.875.
People sometimes think of the vacuum of a pump as “pulling on” the penis, and I admit to sometimes having used such language myself, despite knowing better. It feels like it’s pulling on you, after all. But it isn’t. The vacuum is just removing the very high atmospheric pressure that was pushing in on your penis and preventing it from expanding. It is, in fact, the atmosphere pushing in on the rest of your body, combined with your systolic blood pressure, that is pushing on the inside of your tunica albuginea by acting on the fluid inside your body. That is causing the longitudinal force on your penis in a vacuum cylinder.
I spoke to two guys today on discord; one of them was measuring a consistent 6% BPSFL fatigue after 16 minutes of PB pumping, and another said he was getting 7% fatigue (after edema had faded) at “only” -13 inHg, but that he had gotten to 10% fatigue when he was using -17 inHg. If you use such pressures, let me stress the importance of using very short intervals — 15 seconds or less — with at least 3 seconds of pause either at zero pressure or something like -2–6 inHg to allow fluid to be re-absorbed, otherwise the risk of blisters increases. I have done 200+ sessions where the final 5 minutes were at -17 inHg without getting a single blister, but that’s because I have never done more than those 15 seconds.
Also; as you can see, if you pack a 2.0" cylinder and go to -17 inHg, that’s 26 lbs of force. Subtract 10% and you’re still at 23 lbs of force. That’s a lot. If you are girthy and a beginner, take it easy with the pressures. It’s important to start at gentle pressures and to progress slowly. Beginners should start below -8 inHg and work their way up in pressure a little at a time.
26 lbs of force is also the force with which your cylinder will be pressed into your groin, where the dorsal nerve is close to the surface. That’s why I like to stress the importance of using a good flange with a gentle curvature, or better yet a pump-pad such as the one u/6–12_Curveball sells on https://612printedpolymers.com/
(yes, I know I recommend it a lot, but that’s because I f-ing love it, not out of any financial interest).
I hope someone finds this useful.
/Karl — over and out