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I have a vacuum that shows a max vacuum gauge reading of 23"Hg when connected to a chamber. When placing room temperature water inside vacuum, the water doesn't boil. I have seen this chart before https://www.engineersedge.com/h2o_boil_pressure.htm which indicates that my vacuum pressure is not enough to boil the water at room temp. The chart states that I would need a vacuum pressure of about 29.12 "Hg to boil water at room temp. I understand this. However, I have seen multiple videos of people using water inside a syringe and being able to adjust the pressure (by adjusting the plunger) enough for the water to boil without the need of a powerful vacuum. How is this possible?

Thanks

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    $\begingroup$ Does the vacuum gauge reading of 23"Hg mean that your chamber is at a pressure of 23"Hg, or does it mean that your chamber is at a pressure that is 23"Hg below atmospheric pressure? $\endgroup$ – probably_someone Sep 5 '18 at 21:27
  • $\begingroup$ Are you sure that the syringes in the videos didn't contain $warm$ water? $\endgroup$ – Philip Wood Sep 5 '18 at 21:43
  • $\begingroup$ @PhilipWood I always use alcohol. It's much more dramatic. $\endgroup$ – JEB Sep 6 '18 at 0:44
  • $\begingroup$ I'm going to guess that you have only a mechanical pump, and that you don't have a high precision gauge to tell you how good your vacuum is. $\endgroup$ – dmckee Sep 6 '18 at 14:17
  • $\begingroup$ @probably_someone The chamber is at a pressure of 23"Hg below atmospheric pressure. $\endgroup$ – N. G. R. Sep 10 '18 at 14:38
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Remember that boiling is a phenomena in which the liquid is no longer in equilibrium with its vapor above the surface. If there is already an equilibrium, you won't see the common occurrence of boiling.

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    $\begingroup$ This is true, but without discussing the relationship between the quality of the vacuum and the vapor pressure of water it is rather incomplete and probably dosen't help the OP a lot. $\endgroup$ – dmckee Sep 6 '18 at 14:15

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