sprengel
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Low vapour pressure liquids (room temp)
Looking for any easily accessible/cheap liquids with vapour pressures comparable to or below that of mercury (0.002mm Hg / 0.27Pa).
Not much online about this, thought we'd contact the experts.
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Chemetix
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I woulda thought good ol' silicone oil would have come up as a number one search?
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CaCl2
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Gallium-indium-tin alloy?
Not all that cheap, but also not insanely expensive in reasonable quantities.
The indium is the most expensive component, use as little of it as you can while keeping the melting point high enough.
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Sulaiman
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Quote: Originally posted by sprengel  | | Looking for any easily accessible/cheap liquids with vapour pressures comparable to or below that of mercury (0.002mm Hg / 0.27Pa).
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Welcome sprengel,
based only on your request and username
I guess you are considering making a Sprengel pump?
if so then you also need to consider density
e.g. the drop tube needs to be more than 760mm long if using mercury but more than 10m long if a fluid of similar density to water is used.
CAUTION : Hobby Chemist, not Professional or even Amateur
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JJay
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Sulfuric acid has a low vapor pressure at room temperature. It is not nearly as dense as mercury, though.
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sprengel
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Ok so we never really did much research before coming here, that whole 'not much on the internet about this' thing was a lie.
Anyway, you're right, there's some silicone oil for the range we want for the price we want, so it's between that and dibutyl phthalate.
Thanks
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sprengel
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| Quote: Originally posted by Sulaiman |
Welcome sprengel,
based only on your request and username
I guess you are considering making a Sprengel pump?
if so then you also need to consider density
e.g. the drop tube needs to be more than 760mm long if using mercury but more than 10m long if a fluid of similar density to water is used.
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First of all; yes we are, nice detective work.
We have considered density, and plan on making the capillary 10m long (assuming we use silicone oil or dibutyl phthalate) or possibly altering the
density with temperature or by suspending some kind of weighty stuff in it.
Thanks for the help
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Melgar
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Galinstan (gallium/indium/tin + optional trace amounts of antimony and bismuth) is about $0.50/gram if you make it yourself, and about half the
density of mercury. It's 9/3/1 gallium to indium to tin, by mass. Melting point is similar to water.
| Quote: Originally posted by CaCl2 | Gallium-indium-tin alloy?
Not all that cheap, but also not insanely expensive in reasonable quantities.
The indium is the most expensive component, use as little of it as you can while keeping the melting point high enough. |
Indium and gallium are roughly the same price when purchased at market rates. However, gallium is more popular for individuals to purchase, so the
price is lower since it sells better.
As far as ratio of metals, you actually have to be careful when you're below the melting points of all of the metals. It's really best just to use
the eutectic ratio, because otherwise you can have part of it solidify and part stay liquid, kind of randomly.
The first step in the process of learning something is admitting that you don't know it already.
I'm givin' the spam shields max power at full warp, but they just dinna have the power! We're gonna have to evacuate to new forum software!
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