Silent air compressor as vacuum pump?

[Shyrat]

Hey folks,

So I've been investigating vacuum pumps for a few weeks now.

I've been quoted $900 for an oil free dry vacuum pump from BetterVac. RVD140. Which has a free air flow of 140lpm.

After looking around I noticed that the silent air compressors seem to use the same type of pump, but for $600 you can get a decent sized compressor tank and everything.

Is there a good reason why I couldn't buy one of these air compressors and easily turn it into a cycling vacuum pump?

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[rrich]

I am uncertain of your intended use for a vacuum pump but you may be better off looking for an air conditioning mechanics vacuum pump. Most of these pumps are used to evacuate an automotive air conditioning system before installing/replacing the refrigerant.

[Shyrat]

Cheers for the reply mate, but I'm not looking to use an HVAC oil lubricated vacuum pump. I know they work fine for a veneer press, I know they're cheap.

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[riverbuilder]

I think the valves in such a pump might struggle to hold vacuum pressure. In a compressor situation, once the pump has achieved its set pressure and dhut down, the non return valve on the tank shuts and then bleeds pressure off the cylinder heads, but you will be bypassing this , I think the pump will struggle to start again when under vacuum

[Shyrat]

Ok fair enough. I assume that's the reason why JoeWoodworker in his plans says you'd need a Mac Valve and a sub reservoir to allow the pump to turn back on when it's in vacuum.

Are the dry pumps on these compressors are the same pumps as a specific vacuum pump of the same type? They look identical, but is the only difference in the which port they are hooked up to?

For reference I've attached a photo of the compressor I've seen.https://uploads.tapatalk-cdn.com/20201127/3d0104aa8788c499f92548e95c3237ce.jpghttps://uploads.tapatalk-cdn.com/20201127/792bccdcfd9b60009d0611a13dff430d.jpg

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[Bohdan]

You need to remove the pressure/vacuum off the piston to enable the motor to start under load. The pressure/vacuum pumps only differ in the way that they are connected.

With a compressor, to convert it to vac you don't get everything, you still need to add the vac specific components and these may by quite $$$.

On the BetterVac site you will notice that the vac pumps are all diaphragm and the compressors are piston so there may be an issue with using piston for vac.

It may be a good idea, keep us informed as to how you go.

[Shyrat]

https://bettervac.com.au/wp-content/uploads/2019/03/RVD-DRY-PISTON-VACUUM-PUMPS-AND-COMPRESSORS.pdf

This is the link to the RVD series pumps. They are rocking piston pumps. The RVD140 is the pump I was looking at, it says it does vacuum and pressure.

All this stuff really confuses me! But I just thought this may be an cheapish way to get a cycling system with a reservoir.

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[Bohdan]

The RVD series is vacuum only so there must be some difference to a RPD which is pressure only.

[DaveVman]

Wait, wait, wait! Back up here. SILENT air compressor?
Where do I sign up?

[woodPixel]

Wait, wait, wait! Back up here. SILENT air compressor?
Where do I sign up?

I've the same Chicago silent as pictured. It is an absolute champion. I'm terribly impressed with it.

On vacuum pumps I've this - bought after a long hunt and recommendation - very pleased with it - 70 l/pm 2 Stage Split system Vacuum Pump - HVAC Direct (https://hvacdirect.com.au/70-l-pm-2-stage-split-system-vacuum-pump/)


If you want to use it for a lathe to hold bowls you'll probably want to hook it up to a vacuum storage, such as a reclaimed gas cylinder. There are a few good discussions here that cover off what people have done :)