# Vacuum pump and plastic carboys



## Snafflebit (Feb 14, 2014)

Hi everyone,

I have a new wine equipment project starting, with parts coming from eBay now. It did not start out as wine equipment, but that's where it is headed. I recently bought an Arduino and wanted to make some controller projects. I want to do some motor control projects and bought a variable frequency drive. I need a motor for it and while looking around eBay the cheapest motor was actually a dry vacuum pump. So, I am making a vacuum pump project now. But, this motor is 3-phase 1/2 hp. I can set the speed to whatever I want but I'm sure this motor has the potential to implode a carboy down into a singularity. Exactly how fragile are plastic carboys? The All-In-One pump is probably the way to go, but I am planning for the day when I am filling hundreds of barrels with fine wine.


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## WVMountaineerJack (Feb 14, 2014)

The only way I can see to degass a plastic carboy is to build a degassing chamber so that the pressure was equal on all sides of the carboy inside and out so it doesnt collapse the carboy. It would need to be transparent or have a window to monitor the progress. I put the idea out there to anyone who is handy at building stuff earlier but there we no takers. WVMJ


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## vacuumpumpman (Feb 14, 2014)

A plastic carboy takes less than 4 in HG before it will start to collapse. This is taken from my FAQ;s -
How to incorporate a BB with the Allinone -
Over the years I have figured out how to incorporate the plastic BB carboys with the All In One. You can always pull from a BB or an open container – whether you are transferring, bottling or filtering – you do have to go into a glass container in order to withstand the vacuum pressure otherwise it will collapse. I have talked to many customers who have both types of carboys and this is what I recommend. Transfer from BB to glass to remove CO2 and sediment. The glass carboy should be higher than the BB for the next time you transfer; you can start a small vacuum, only to get the gravity to work for you and then turn off the pump. This way there is still no lifting heavy carboys !!


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## richmke (Feb 14, 2014)

> Exactly how fragile are plastic carboys? 

I did the transfer once. Like Steve said, put the plastic carboy below the source so gravity can do most of the work. Use the least vacuum you can.

The plastic carboy will slightly implode as the vacuum builds. Once the siphon action has started, turn off the vacuum pump.

I would guess that the repeated implosion will fatigue the plastic over time.

At best, I would use the plastic only for the initial transfer from the primary. The CO2 in the wine will protect it from oxidation. After that, glass only to minimize the air contact.


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## turkeylipz (Feb 14, 2014)

snafflekid said:


> this motor is 3-phase 1/2 hp.




3 phase? As in industrial 3 phase? Not sure how well that would run on household power...

How are you integrating the controller?


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## Snafflebit (Feb 14, 2014)

The controller takes either 208V 3 phase supply or 240V single phase supply and converts that to a variable frequency 3 phase voltage to control the AC induction motor. I will be powering the controller with the single phase 240V from the dryer socket. This is definitely an industrial-type design. The controller is kind of like a minicomputer that can set controlled speed, acceleration, deceleration, braking, fault detection.


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## vacuumpumpman (Feb 14, 2014)

I would be mor concerned about your LPM and how much vacuum you will be pulling ? 
Both of these work harmony together - if one is off the outcome will not be what you want. Too much LPM and vacuum can cause excessive stress on your equipment.


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## Snafflebit (Feb 15, 2014)

I am seeing 20 in. Hg used a lot for the vacuum pressure in wine pumps. I was making an assumption that having a variable speed pump would be a useful feature but maybe it is not. Should I put a pressure regulator on the overflow tank, set it to 20 and forget it?


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## vacuumpumpman (Feb 15, 2014)

snafflekid said:


> I am seeing 20 in. Hg used a lot for the vacuum pressure in wine pumps. I was making an assumption that having a variable speed pump would be a useful feature but maybe it is not. Should I put a pressure regulator on the overflow tank, set it to 20 and forget it?



Like I mentioned before - what is your LPM ?


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## WVMountaineerJack (Feb 16, 2014)

If you set it and forget it you are going to come back and get a big pile of foam, its better to start at a low vacuum and work your way up. Are you still trying to do this on plastic carboys? WVMJ


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## Snafflebit (Feb 17, 2014)

I do not know what is a reasonable flow rate for wine. There are 20 liters in a carboy. I would start with 20 liters per minute to get the carboy emptied in a minute. My guess is this requires unreasonable negative pressure, but it is a starting point.

Wikipedia has a formula for flow rate versus pressure difference: 

Δp=fD*(L/D)*(ρ*V^2)/2

This is overcomplicating things but one important point from the formula is that the pressure drop is proportional to the square of the fluid velocity, all else being equal. To double the fluid velocity one must quadruple the pressure difference between atmosphere and the transfer vessel. Which is interesting and says there is diminishing returns to increasing the vacuum. I have not seen vacuum pumps used at wineries despite their benefit of being gentle on the liquid, maybe this is why? The containers can't handle the pressure.

I will be doing transfers between my plastic carboys the old-fashioned siphon way.


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