I’m brand new to making composites and I’m looking to start out doing some resin infusions and maybe some prepreg down the line.

As I’m new to this hobby I don’t to spend too much money on a vacuum pump as I’m unsure if It’s a hobby I’ll really get into or not.

I had been told by my brother I needed a dual stage pump (I’m assuming he meant for infusions).

I was looking to do quite small jobs. I’m not making boats, probably never do any car sized panels, but a bit smaller.

Do I really need a dual stage pump?

For reference the pump I was looking at was “4.5CFM 2 Stage Refrigerant Vacuum Pump Refrigeration Air Condition 128L/MIN” made by VEVOR.


Any help would be appreciated

You need a pump that is capable of very high vacuum. 99.95% is generally the accepted minimum. Don't pay too much attention to the CFM rating, that only describes how quickly the pump can evacuate the air from a bag, which isn't  concern for smaller parts. 

+x

 

Hanaldo - 6/18/2020 2:57:39 AM

You need a pump that is capable of very high vacuum. 99.95% is generally the accepted minimum. Don't pay too much attention to the CFM rating, that only describes how quickly the pump can evacuate the air from a bag, which isn't  concern for smaller parts. 

Ok I won’t. Does the CFM relate to how much of a vacuum it can pull?

The listing claims it’s has an absolute vacuum of 0.3Pa, is this enough?

No, CFM is Cubic Feet per Minute. So simply refers to how long the pump will take to move a given volume of air. For vacuum bagging small parts, this is the difference between your pump taking 2p seconds to pull vacuum on a bag or 2 minutes to pull full vacuum - it's not worth worrying about. When you get up to making boats in a production environment, then you might not want to wait 20 minutes to pull full vacuum and it's worth getting a bigger pump.

All you are worried about is maximum vacuum; and yes, 0.3 Pascal is super high vacuum - so high that it makes me suspicious...

Yeah I wasn’t paying too much attention to the flow rate, it’s was that 0.3Pa that didn’t make sense. Something doesn’t seem right.

Do I really need a double stage vacuum pump for resin infusion? I won’t ever be making anything as large as a boat and probably never anything as large as a car panel.

Personally, as a startup, this would be more than adequate, IMO.

https://www.ebay.co.uk/itm/3CFM-1-3HP-Refrigerant-Rotary-Vane-Vacuum-Pump-A-C-Vacuum-Evacuation-Pump-UK/332546641825?epid=1949101799&hash=item4d6d530fa1:g:1MIAAOSw9qJaeqPd

Thanks for the suggestion. That was the original pump I was looking at before I was told I needed a 2 stage pump.

So the pump you suggested can go down to 5 Pa? So this is still apparently far stronger than the EC.4 pump? This is what is confusing me

No, single stage (oiled) rotary vane pumps are sufficient. 0,3 is a relatively normal number for dual stage pumps. But you will not need such a high vacuum. You could use it, but a cheaper single stage pump will do the job equally good.

Ok that’s great, thank you and everybody for the advice on this, think I’ll get one of these cheapy pumps.

Does anybody actually use one of these VEVOR pumps?