Vosoryx - 29-9-2017 at 17:04
I am trying to win the hotplate stirrer from http://www.sciencemadness.org/talk/viewthread.php?tid=74020
as I have been for some months now. Each attempt gets me closer, but not quite there. After referring with someone who teaches chem, I'm pretty sure
that at this point in order to proceed I need a vacuum pump. However, cost becomes pretty prohibitive for a good one.
I would use an aspirator which is within my price range, but ammonia is a pretty major by product and I don't think my pump would like being in
extremely basic water for two hours.
An idea of mine came up: I could a vacuum cleaner, as all it really needs to do is suck the ammonia out in a reasonable time, and maybe lower the BP
by a few degrees.
My concern is this: vacuum cleaners cool down their motors with passing air over them. If I were using it as a vacuum pump, there would not really be
any passing air, so it would overheat rather soon. If I used multiple, would I give the motors enough time to cool down? How many would I need?
Is this idea economical at all, or is it just as stupid and pointless as most of my ideas? let me know if I'm just unnecessarily complicating this and
the obvious idea is just staring me in the face- that's happened before.
~Vos
VSEPR_VOID - 29-9-2017 at 17:08
I wouldn't count on the vacuum cleaner holding up to the fumes and moisture. You could just keep the solution your original pump in slightly acidic.
Have you considered using cold vinegar or maybe even some sort of buffer?
Vosoryx - 29-9-2017 at 17:51
I wanted to avoid adding acid because I didn't want to overshoot and put my pump through acidic conditions, but putting in a buffer acid would
probably work quite well. Thanks.
XeonTheMGPony - 30-9-2017 at 05:12
it will die fast and with lots of smoke.
they are series wound brushed motor, they run hot, they use the air flow over them to cool, that is why it is bad to not change the bags in the
cleaner for too long.
In your idea there will be no air flowing over the motor.
the heat will blow it long befor any acid vapors or moisture will!. But you're aware of this and no there is no viable work around and the vacuum
generated will be use less bin the idea!
A water asperiator will not care about ph of the water, run it open loop and water the yard! the plants will love the ammonia spread out and diluted.
they aren't hard to make if space is a concern.
[Edited on 30-9-2017 by XeonTheMGPony]
unionised - 30-9-2017 at 05:22
"vacuum" cleaners hardly generate a vacuum at all.
Typically a fan will "stall" once the pressure difference across it is a few inches of water.
vmelkon - 6-10-2017 at 07:08
Yes, a vacuum cleaner generates a weak vacuum.
1. There are other methods like have a steel can. Fill with water a bit and boil and close the top. Let it cool.
2. A method I used to make a lightbulb ----> Put NaHCO3 in your glassware. Use a hand pump to remove as much as the air as possible. These hand
pump cost 50 to 60$. Heat the glassware to 150 to 200 C. The NaHCO3 decomposes to Na2CO3 + CO2 + H2O.
Use the hand pump again to remove the hot gases as much as possible. As it cools, pressure drops even more. Then wait for 1 day, the H2O has is
absorbed by the Na2CO3 and YOU END UP WITH A STRONG VACUUM.
[Edited on 6-10-2017 by vmelkon]