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Vacuum Pump Control

For those interested in the use of composite materials
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Philkiteflyer
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Re: Vacuum Pump Control

Post by Philkiteflyer »

Mick Tomlin wrote: 19 Feb 2021, 11:58 . . . . . my computer experience extends to turning them on and off.
Mick
You must work in our IT department . . . :lol: :lol: :roll:

Phillip C
"Keep it simple stupid"
Mick Tomlin
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Re: Vacuum Pump Control

Post by Mick Tomlin »

Yep
Employed to change the fuses
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mjcp
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Re: Vacuum Pump Control

Post by mjcp »

I'm intrigued by this post as I had a hankering to re-purpose an old airconditioner's pump for bagging etc.

I am a little confused as to where the two grey cylinders are from. I assume they are tanks used to maintain some "store" of vacuum? (much like a compressor in reverse?)

Would my old ac unit have these? If not, where to source and are there guide line on volume / strength etc to be followed?


thanks in advance!

M
m̶j̶c̶p̶ Marc

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Some (now) pristine models that are un-flown for a year.
Mick Tomlin
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Re: Vacuum Pump Control

Post by Mick Tomlin »

Mark
This set up should work with any pump arrangement as it basically controls the power to the pump.
Only thing to take note of is the start up currant for you pump and ensure that the relay is man enough,
The small white tank is 1nch water pipe and acts as a check to stop the pump trying to start with a vacuum as this it can stall the pump.
The two gray tanks I used some soil pipe that was lying around with end caps. Each is 100mm diameter x 300mm length
They give some back up vacuum that smooths the operation and aids having to run the pump more than necessary.
I bagged some 1.75mt wings and with a good seal on the bag the pump ran for less than 30 seconds over the 12 hours.
To give some idea of scale my unit measures 400mm wide, 250mm deep. 300mm high.
Hope that helps
Mick
By the way the wings are for my PIK 20.
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mjcp
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Re: Vacuum Pump Control

Post by mjcp »

Me again... back on the vacuum idea.

Over the summer we had the mis-fortune of our portable ac unit failing.. luckily the compressor stayed hear while the rest went to the tip; my hope is I can use the compressor as a vacuum pump?

Do I have the right idea or is this a bit beyond possibility?

Pump specs (Link to PDF on ext. site)


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m̶j̶c̶p̶ Marc

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Some (now) pristine models that are un-flown for a year.
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Peter Balcombe
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Re: Vacuum Pump Control

Post by Peter Balcombe »

Marc, there are plenty of uTube videos on converting a fridge compressor into a vacuum pump, so I guess your compressor is essentially a bigger version of a fridge unit?
Just need to identify which pipe is ‘suck’ & which is ‘blow’.
Make sure you have all the starter electrics & know what you are doing regarding electrical safety - else make sure you get a competent person to look after that bit :)

Having just looked at the data sheet, I see this is a rotary type, but I guess it should work ok as long as you have a non-return valve in the system (unless there is already an internal one)?
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mjcp
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Re: Vacuum Pump Control

Post by mjcp »

Thanks Peter,

Not sure about the non return - trial an error should confirm that! As for the electrics... 25+ years in IT.. I haven't zapped myself yet ;)

I assume these are designed for a specific refrigerant i.e. R-407c in this case. Is there an issue in the conversion where its now pumping/sucking air? Does the refrigerant offer any lubrication or sealing properties to the pump ? (or are we assuming little use/hobby use and therefore minor issue over time?)

Marc
m̶j̶c̶p̶ Marc

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Some (now) pristine models that are un-flown for a year.
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Peter Balcombe
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Re: Vacuum Pump Control

Post by Peter Balcombe »

Marc, from what little I know/have seen on the web about A/C rotary compressors, they probably cope with any gas refrigerant - it’s just that the R407c is possibly the one the compressor was type tested with. Car A/C units seem to use one of 2 types of gas & it may depend on what was current when the car was manufactured?

As far as I can make out, the (normally) gas comes in via the side unit which contains a particle filter & the ability to retain/boil off any liquid coolant which happens to make it from the condensing (cooling) coils.
The pump data sheet does mention oil, but I expect that is in there to lubricate/cool the pump mechanics.
The exhaust (pressure side) seems to be the top tube which normally goes off to the evaporator coil (an external unit with fans) to get rid of the heat extracted by the cooling coils + pump compression heat.

Typical A/C arrangement
Typical A/C arrangement

Your pump is pretty powerful compared to a normal piston type fridge compressor, so able to shift a lot of gas/air. You might need to be able to start the pump & let it get to speed before trying to put on load. You can do this by opening a pump relief valve for a short time each time the pump starts, letting it get up to speed.
Even more important to use reservoir tanks with this pump methinks.
Peter
Mick Tomlin
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Re: Vacuum Pump Control

Post by Mick Tomlin »

Hi Mark.

Peter is correct and your compressor pump will probably work very well.
How do you intend to control the vacuum as this is the issue when bagging composites, especially foam core items.

Mick
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Peter Balcombe
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Re: Vacuum Pump Control

Post by Peter Balcombe »

This is where the thread started, based on the RC Groups vacuum controller thread.

The controller uses a small Arduino processor unit to sense vacuum level & control pump run/manifold valve operation via a couple of relays to keep the vacuum within defined limits.
One relay switches the pump on/off whilst the other operates a solenoid valve to take the pump off load (if needed) whilst it runs up to speed.
The reservoirs should greatly reduce the number of times the pump needs to run once the required vacuum has been pulled on the bagged components during the cure time.
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