Don't burn your unit under vacuum

I keep reading about guys who heat under vacuum and then get burnt surprisingly fast.

Under a vacuum, temperature rises much quicker than it would not in a vacuum. For example, at normal air pressure, water boils at 100 C. Under vacuum, it can be 70 C depending on the level of vacuum.

So, be careful. Just because it does not feel too hot before vacuum, doesn’t mean it won’t get very hot in a hurry under vacuum.

I am expecting my LA pump today and am pretty excited. Already bought KY and a heating pad!

What exactly do you mean? I always let my junk soak in warm water, and I soak my lube and tubes in warm water in the sink too. How do you know if it’s too much heat?

Trial and error. Everybody has a different tolerance for heat/pain.

Where do you ‘keep reading’ about this?

I believe you are inaccurate in two respects.

First, vacuum tends to decrease heat transmission. That’s the theory behind Thermos bottles. The vacuum impedes heat transfer.

Second, the level of vacuum used in pumping would results in a modest reduction in boiling point at most. I wrote this when this concept was brought up before:

According to http://hyperphysics.phy-astr.gsu.ed…tic/vappre.html , "Raising or lowering the pressure by about 28 mmHg will change the boiling point by 1°C." I’m looking at the gauge on my pump right now. Increasing vacuum by five inches is about 120 mmHg. So if I’m pumping at five inches (and I generally pump at less than that), I have decreased the boiling point of water by a bit more than 4 degrees C; to 95.8 degrees C or 204 degrees F. Go crazy and pump at 10 inches (about 260 mm), and you’ve decreased boiling point by 9.3 degrees C; to 90.7 degrees C or a bit over 195 degrees.

Hi Lampwick,

I believe that the vacuum in a thermos would reduce heat transfer between each side of the vacuum (ie.the product and the outside), but the activity of any molecules within the vacuum would be higher due to essentially more less resistance. Steam is hotter than water because the molecules move faster and are farther apart.

You may be right in your calculations, I just don’t have time to do the math right now (although is sounds correct at first glance).

That said, if someone is pumping with 10 inches (ie. almost 10 C), that can easily be the difference between being hot and burnt. 65 C is warm. Try sticking your dick in 75 C water and let us know how comfy it is.

I put in the comment because I have seen several people mention that they have burnt/almost burnt themselves under vacuum. Just a cautionary note.

PS: not trying to be bitchy, just make a point. I have lot more to learn than offer in knowledge- and know it.

A thermos has a vacuum separating two different heat systems. If you notice, a thermos has the unit holding the liquid, then an empty space (the vacuum) then the outer cover.

I don’t know about oyu guys, but when I pump, I feel the tube get quite warm, I’m assuming from the heat transfer from my penis to the tube.

I wrap an electric heating pad around the tube when I pump. I can definitely feel a lot of heat coming through. I’ve never put my dick in the heated tube without vacuum for comparison, but it seems that it gets hotter than I would have expected. I have had to remove the heat pad occasionally because it was too warm, but I’ve never gotten close to burning myself.

Lampwick is right, of course. The higher the pressure, the higher the temperature :

that’s how pressure cookers work.

Your link shows: PV=nRT

Doesn’t that mean that n (#of particles) is inversely proportional to T (temperature)? If so, the fewer the molecules, the higher the temperature. There is no doubt increased pressure with a constant Volume of molecules increase temperature, but when you reduce n, a different mechanic is at work.

Actually, I had noticed, but thank you anyway.

The vacuum of the thermos impedes heat transfer whatever the direction of the relative temperatures. If it holds hot contents, it impedes heat dissipation to the relatively cooler environment. If it holds cool contents, it impedes heat transfer from the relatively warmer environment to the thermos’s cooler contents.

My tube can get warm through the course of a session, but I believe the mechanism of heat transfer in that case is primarily through contact and direct conduction. I’m going to guess that the tube is warmer near the base than at the distal end, but that is just a guess. I’ll see if I can measure the next time I pump.

Also keep in mind that what we do via pumping for PE is far from absolute vacuum. It is a reduction in pressure compared to ambient atmospheric pressure.

The bottom line for me is to be careful in application of heat during pumping. Whatever relative vacuum level is involved is not as important as how much heat is being applied.

You reduce n? How 'you reduce n'? Are you understanding what you read?

You reduce n (number of particles) by creating a vacuum. By definition a vacuum is an enclosed space from which matter, esp. air, has been partially removed so that the matter or gas remaining in the space exerts less pressure than the atmosphere.

Yes, I think I am understanding what I read.

Rewritten:

T= PV/nR

Create a vacuum and you reduce n. Reduce n and you increase T.

This thread makes me feel ignorant…

First, I don’t think you reduce n because when air goes off more penis goes in.

That said, V and R are constant, so you have : P=nT then, T= P/n; so, the higher the pressure (helding n unchanged), the higher the temperature; the smaller the n (helding the pressure unchanged), the higher the temperature.

So, being a vacuum a state of lower pressure, it lowers temperature.