ekolo (Hive Bee)
03-15-04 20:21
No 495326
       water aspirator     

I read the post on Rhodiums site(../rhodium /equipment/aspirator.html) about building an water aspirator but how strong is an water aspirator in Inches Hg if the water pressure of the pump is 40psi. 		 
 
 
 
    silenziox
(Hive Bee)
03-15-04 20:42
No 495331
       I'd suggest using kilopascals and mmHg instead     

I'd suggest using kilopascals and mmHg instead of psi/bar /inHG..

http://www.chemsoc.org/exemplarchem/entries/pkirby/exemchem/Nomograph/Nomograph.html

There is also Imperial-version of this... I won't search it down. cool

Did you try to search google for words "psi inch hg"?
Here's good table for high vacuum: http://www.lds-vacuum.com/conversion.html


1 micron (u) Hg = 0.001 mm Hg = 10-3 mm Hg
1 millitorr = 1 micron (u) Hg = 0.01 mm Hg
1 millibar (international) = 0.75 mm Hg
1 bar (international) = 106 dyne /cm2 - 29.53 inches Hg
1 barye = 1 dyne/ cm2
1 newton/m2 (pascal) = 10 dyne/ cm2 = 7.5x10-3 torr
1 newton/m2 (pascal) = 7.5 millitorr = 7.5 micron
1 millimeter Hg = 1000 microns = 10-3 microns = 1 torr
1 millimeter Hg =1.333 millibar = 133.3 newton /m2
1 millimeter Hg = 0.03937 inches Hg = 0.01934 psi
1 torr = 1 mm Hg = 133.3 newton/m2
1 atmosphere = 760 torr = 14.7 psi
1 psi = 2.036 inches Hg @ 32oF = 51.72 torr
1 psi = 2.041 inches Hg @ 58.4oF
1 inch Hg @ 32oF = 0.4912 psi
29.921 in Hg @ 32oF = 14.696 psi = 760 torr
30.00 in Hg @ 58.4oF = 14.696 psi = 760 torr

And the answerfor your question is: 40psi = 81,44 Inches Hg @ 32'F
Off We Go!laugh 		 
 
 
 
    ekolo
(Hive Bee)
03-16-04 11:47
No 495476
       no i did not do a google search just wanted to     

no i did not do a google search just wanted to se if someone had some expirience with it. its because i have smal water compresor and its a powerfull one, its working presure is at 1600psi or about 110 bars. just wanted to know how strong such water aspirator could bee if it was at 40psi. thanks for the help.

just a question is such a water aspirator(40psi) good enough to vacuum destil ketone or sassafras oil or is it imposible. thanks. 		 
 
 
 
    ApprenticeCook
(Hive Bee)
03-16-04 13:16
No 495485
       fine     

That should be fine, just need to find out the specs of your aspirator, some are different, example swims aspirator at 1Kg/cm2 water/air supply can pull 15mmHg.

The way swim does it is to have a "T" joint in the vacuum line between your aparatus and aspirator, connect the aspirator straight through and a vacuum gauge (automotive one is fine, but they are usually in InHg not mmHg) to the other port, this allows you to see the vacuum reading and using the nomograph here:
../rhodium /equipment/nomograph.html
To  find the boiling point of the substance at that pressure.
Convert mmHg, InHg, Torr, atm etc... here:
../rhodium /equipment/conversion.html

Hope that helps.
-ApprenticeCook 		 
 
 
 
    a3d0a3m
03-18-04 06:28
       Pull
(Rated as: misinforming) 		    
 
 
 
    killabeezwax
(Stranger)
03-18-04 09:54
No 495890
       kitchen faucet pressure     

I know that a kitchen faucets pressure is sufficient enough for a 30 mmHg (system was very chopped together-sort of a dry-wet run :), pressure may actually be higher).  I'm betting your 40psi is much more substantial than a kitchen faucet.
KBW 		 
 
 
 
    moo
(Hive Bee)
03-18-04 11:02
No 495897
       Your water pressure has to be real shitty or...     

Your water pressure has to be real shitty or your aspirator way too big to end up in a situation where the vacuum was not dictated by the temperature of the water or actually the vapour pressure of water at that temperature.
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