Vacuum pumps?

[Daniel C.]

Hello,

I'm looking for an affordable vacuum filtration setup (funnel, filter, Buchner flask, and vacuum pump) and it's hard to know how cheap I can go before I risk buying something that will break within a year or just not work.

Has anyone put together a system like this?  What products / brands have you had success with?  I'm particularly interested in pump reviews.

Thank you,

Daniel Crookston

[Tom Knight]

Cheapest is likely to be an aspirator instead of a vacuum pump.

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[John Griessen]

On 7/25/20 9:01 PM, Daniel C. wrote:
> Has anyone put together a system like this?  What products / brands have you had success with?  I'm particularly interested in
> pump reviews.

I have not, but there are hackaday articles about repurposing refrigeration pumps to do vacuum. They talk about ongoing vacuum
oil maintenance needed, etc., so that's your requested review. To simply speed filtering, a 90% vacuum would be enough. You
could make a system with pressure switch and relays to turn on/off a tiny fridge compressor. The pressure switch could be one of
the pressure ICs available, or for completeness, an Industrial Pressure Sensor that includes switch contacts and pipe fittings.
The price of the Industrial pressure switch is about $36 from Mouser and a Melexis IC is $12. For $12 you get a 5 volt output and
some complicated way to adjust the trip point that will require programming a microcontroller and then you'll need relay drivers
or a SSR for another $10 in parts and loads of design time, so the Industrial pressure switch for $36 looks good for a one off.

Running a small fridge compressor this way would not strain it, (unless you left the vac valve open all weekend maybe...).

[Simon Quellen Field]

I agree with Tom Knight -- all you really need for that purpose is an aspirator.

An old vacuum cleaner from a garage sale would also work fine or a little Dustbuster.

For vacuum filtration, you really don't need much.

On the other hand, I have a very nice little 2-stage vacuum pump made by CPS Products, the model VP6D.

You can get one for about $300.00 brand new.

Or you can get its little brother, the 1 stage VP2S for half that.

They are both overkill for your project, but they are great fun to play with.

I can make solid nitrogen by pumping down a Thermos full of liquid nitrogen.

And they are quite a bit quieter than a household vacuum cleaner.

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