Half a croissant, on a plate, with a sign in front of it saying '50c'
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Vacuum 'Boil Off' Hand Dryer

The drier dryer
  [vote for,

To bolster its environmental kudos (and pressumably to reduce costs), the organisation at which I work has recently replaced one of the two paper towel dispensers in each washroom with a snazzy, electric, wall-mounted hand dryer. They did a short trial with three different vendors' products in a couple of washrooms before rolling out the winner, a slick, stainless Dyson slimline model, to the rest of the building.

Now these dryers work well enough, but they're not as effective as the paper towels they replace as they take longer and require one to contort one's hands and wiggle them about to get sufficient coverage. Plus they are incredibly noisy to the point where I feel people are inhibited in using them. Not to mention the occasional scares from the press and from the office grapevine that, by drawing air from the washroom, these devices are spraying fine faecal matter onto the hands of those using them, effectively undoing the prior hand washing efforts.

So, naturally, I was pondering how these devices could be improved, and then my elementary science knowledge kicked in and blessed me with a eureka moment: what if rather than blowing the water from my hands it could be boiled off instead. Would that not be a more triumphant way to dispose of the excess moisture from one's digits than the glorified fans that these hipster design bureaus are peddling?

A quick visit to Google Images later and I had the chart I needed, plotting the boiling point of water against pressure. Obviously one would not want one's hands to be boiled dry at 100°C, for that could cause some discomfort, so our newfangled hand dryer would have to lower the pressure somewhat, for, as we all know, the boiling point of water descends as does the pressure. From my chart I could see that the pressure would need to be fairly low before we would get into the realm of tolerable temperatures, so the dryer would need to create something close to a vacuum.

So I envisage a container mounted upon the wall, a lot like a conventional, electric dryer, with two holes upon the front through which one would insert each hand. A silicone rubber sphincter would then tighten about the wrists to create a near air- tight seal. A couple of small jet engines would then spring to life, pumping the air from the chamber to lower the internal pressure based upon the ambient temperature, such that the moisture upon the hands would reach boiling point. This would mean that on warmer days it would be possible to create a marginally lesser vacuum.

The user of the device would then wait a few seconds whilst the water gently boiled off of their hands, the sphincters would then almost certainly release their grip from around the user's cuffs and they would be free to walk happily from the washroom with bone-dry hands and only minor bleeding from the fingertips.

(If the jets prove to be too noisy then the chamber could be built to expand, like a syringe, by pneumatic jack thus lowering the pressure by increasing the chamber volume.)

oniony, Jan 04 2019

Lead hand dryer https://www.youtube...watch?v=yTOCAd2QhGg
[bs0u0155, Jan 04 2019]


       //A silicone rubber sphincter would then tighten...// - I can think of no other alternative uses these devices might be put to by mischievous or adventurous individuals in the average public toilets.

Another approach to this problem might be to have the entire room at a reduced pressure. Users would have to hold their breath, but this is a fairly common requirement already in some public toilets. A side effect might be that a reduced ambient air pressure might assist the exertions of those with constipation.
hippo, Jan 04 2019

       I did actually have the idea of a shower cubicle sized box that could be depressurised for full body drying but that scene from Total Recall with Arnie's bulging eyes still haunts me.
oniony, Jan 04 2019

       ... as indeed it does everyone who has ever seen that movie.   

       We like this idea, and award it a vacuum-dessicated croissant. The idea of employing tiny gas turbines, while technicaly impractical, is particularly praiseworthy. [+]   

       We also commend the designer for // only minor bleeding from the fingertips // which shows a nicely robust and uncompromising approach to product safety, and the health and wellbeing of users.
8th of 7, Jan 04 2019

       I think touch is the crux here and those cuffs might have more than the natural amount .
wjt, Jan 04 2019

       //the organisation at which I work// Hey! One of us got a job!! Well done that Halfbaker.   

       Part of the problem could be solved by replacing the water taps in washrooms with ethanol taps. Ethanol has the advantage of sterilizing hands more effectively than soap and water, so there'd be a saving on soap for starters. And then, when it comes time to dry, ethanol's lower boiling point would come into play. Flammability issues would need addressing, but I can't see that being much of an issue.
MaxwellBuchanan, Jan 04 2019

       The ethanol could be filtered and recycled; but we forsee a potential problem of users abstracting the liquid for use as vehicle fuel.
8th of 7, Jan 04 2019

       //we forsee a potential problem of users abstracting the liquid for use as vehicle fuel.//   

       Use a reasonable gin or scotch. Most vehicles won't run on that without a lot of tedious re-tuning.
bs0u0155, Jan 04 2019

       Actually, I think I've got it. Silver/Copper are both pretty potent antimicrobial materials. Hot things are good at flashing off a little water to steam, so why not have a bath of molten silver by the door, a quick dip and shake and your hands should be dry and sanitized. Mythbusters showed it was perfectly safe using lead I think, but lead isn't in the same league as silver/copper when it comes to antibacterial action.
bs0u0155, Jan 04 2019

       Why not use a liquid with a strong affinity for water - concentrated sulphuric acid, for example ?
8th of 7, Jan 04 2019

       //liquid with a strong affinity for water//   

       ah, liquid sodium then. Or potassium for those watching their blood pressure.
bs0u0155, Jan 04 2019

       Given that its freezing point is -12C, NaK is the obvious candidate material in this application.   

       Since it's pyrophoric, it might be advisable to fill the room with an inert gas; Argon would be best.
8th of 7, Jan 05 2019

       If a prankster were to tamper with the seal mechanism it would make for some wicked arm hickeys.   

       Yes, but what sort of sick, cruel, reckless and sociopathic person could even contemplate such a wicked, spiteful act of twisted and irresponsible vandalism ?   

       Apart from you, that is.
8th of 7, Jan 05 2019

       This idea sucks rather than blows. I like it.
AusCan531, Jan 05 2019

       //what sort of sick, cruel, reckless and sociopathic person could even contemplate//   

       Yes, well, you don't get to survive them without learning how they think.   

       Hand dryer is only for hands. Do not place other body parts in the hand dryer.
bungston, Jan 10 2019

       Oh, indeed. Imagine thrusting your damp appendages into the dryer, wanting nothing more than the rapid and hygenic removal of surplus water, and finding that a previous user has deposited a disarticulated foot in the device ...
8th of 7, Jan 10 2019


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