Sulaiman
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Very quick review of a 12v air/vacuum pump
I bought one of these
Mine had a broken out barb but otherwise ok
It would be good for bubbling air etc,
good flow rate and pressure, not too noisy.
It does pull at least - 65kPa relative to atmospheric, (sea level + 25m)
but I recommend against it as a vacuum pump (for filtration) because,
the gas passes all of the internal mechanisms,
including the exterior of the motor bearing and shaft,
and passes through convoluted long narrow paths,
presumably subject to blockages.
It does work, and would probably give hundreds of hours of service if 'nasty' gasses are not involved,
which,for the cost, is ok.
My reference is a similar 12v piston pump that I've used/abused a lot.
(-80kpa new, - 70kPa now, runs for days continuously, noisy)
[Edited on 1-7-2024 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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drkcc
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Thank you for your review, I always appreciate if someone puts out some hardware information! Could you also give us the part numbers or suppliers of
these pumps?
A quick google search later, the closest match I could come up with are Pumps from Deltakit Electronics and Robotics Parts. There are two similar
models, one with a three-screw lid flange and another with a five-screw flange. (https://www.deltakit.net/product/micro-air-pump-6vdc/ and https://www.deltakit.net/product/15l-high-flow-555-vaccum-pu... respectively.)
I believe it is the former pump, but I'm not quite sure. Could you confirm if it is one of those? Please also tell where you got your piston pump
from! Thank you!
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Sulaiman
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Posts: 3944
Registered: 8-2-2015
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I do not recommend either of the two air pumps above ! 
assuming that you want a vacuum pump for filtrations,
once the filter flask is evacuated the airflow through the pump is the same rate as liquid through the filter (plus any air leaks)
... negligible in terms of pump capacity.
So you only need a small pump - choose by negative pressure capability,
I have not seen a vacuum pump of any size that could not handle the air leakage rate.
the large air pump above is well suited for lots of bubbles in an aquarium or pond,
as a vacuum pump it sucks air/gasses through the chamber with the motor and pump bearings and then some narrow passages.
the piston pump shown is still usable but now only -70kPa (adequate) and noisy, and probably ready to die soon,
so I bought the big round one, ok but unneccessary.
Then I bought a VN-C4 as used by keras,
there was a crack in the plastic so I returned it -after testing,
very good but overkill for filtration.
now I'm using a 1usd 3.7 to 5 V pump !
any air pump with an inlet port (and an outlet port) will work !
I bought a dual-stage rotary-vane oil-sealed vacuum pump (relatively cheap Chinese HVAC type)
for vacuum distillations and filtrations. 
I can't use it for filtrations as it boils water at ambient temperatures 
and I don't use it for distillations (yet) for fear of corroding it
I've changed the oil more times than I've used it for distillation,
but it does still look nice 
[Edited on 26-12-2025 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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drkcc
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Oh, it seems I have misunderstood. I have been looking for pumps for vacuum distillation. Being able to use them for filtration is a neat extra, but
not their main purpose.
I suspected that a lot of pumps would be able to handle filtration, destillation will likely be more difficult.
I would have considered the small pumps you posted as well as I likely would not run them for very long anyway, but I suspect that these are a little
small for destillation.
The VN-C4 looks like a nice golden middle - it would likely suffice for a small scale setup such a mine. Would you agree that the listed pumping speed
of 40 L/min is enough to handle ~1L flasks?
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