Lister Engine Forum

Alternative fuels => Waste Vegetable Oil => Topic started by: veggie on June 18, 2018, 12:53:26 AM

Title: WVO Centrifuge Design - thoughs ?
Post by: veggie on June 18, 2018, 12:53:26 AM
Hi All,

I have a design question as I fabricate a WVO cleaning centrifuge.
My initial design shown below incorporates a single tank with the "Fuge" mounted above.
The 26 liter tank will incorporate a sight level tube and a 1000 watt heating element.
The idea of the small tank is that I can process a Gerry Can at a time for small batches.
There will be a small gear pump mounted on the side of the tank which continually circulates the WVO
 up to the centrifuge where it gets cleaned and falls back to the tank.
Theoretically, the longer the unit runs, the more passes the WVO gets through the centrifuge.

Most users of this type of Fuge have a two tank system. One above which uses gravity to the feed the Fuge, and one below to collect the cleaned oil. Then they pump the cleaned back oil up to the original tank for another pass. This ensures 100% contact time for all the oil.

My Question:
After a lot of Youtube digging, I have not seen anyone use a single tank system like mine which makes me wonder...
Will ALL of the oil pass through the centrifuge 100% or will there be pockets of un-cleaned oil that never make the loops?
For me, the single tank system is a real space saver and I don't mind leaving the system running longer in order to get multiple passes though the fuge. But will ALL the oil get processed given a long enough run time?

Anyone with experience with this?

Cheers,
Veggie

Tank = 7 Gal (26 liter)
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: mike90045 on June 18, 2018, 01:42:38 AM
If you can keep the oil thin and agitated, for long enough, it will be clean "enough"   Since it's operating in "bypass" all the time, all the clean oil you put back in, gets dirty.  Lather, Rinse, Repeat.

At some point, you have to put the clean oil somewhere.
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: glort on June 18, 2018, 02:18:49 AM
Quote
But will ALL the oil get processed given a long enough run time?

Yes.
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on June 18, 2018, 03:18:16 AM
At some point, you have to put the clean oil somewhere.

Ha..Ha...Yes, after several processing loops with the centrifuge spinning at 5000 rpm, the oil should be very clean.
At that point a valve gets opened and the pump pushes the processed oil into a clean oil storage tank.
Then the green centrifuge tank gets filled again with dirty oil.
The fats and particles collect on the inner wall of the centrifuge drum for cleaning later.
That's the plan anyway.  ;)

The Drum was purchased from a centrifuge manufacturer and mounts on the shaft you see in the center of the housing base..
The housing was fabricated from pipe.
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: EdDee on June 18, 2018, 03:18:13 PM
Hi V,

While it will certainly clean the vast bulk of the debris, I, personally, am going a slightly different route in the bits I am getting together... I will be using a "fill tank" to dribble the oil through the fuge first time round to collect most of the junk... thereafter it will be a single tank system which will recirculate until shut down...

Just my 0.00c worth.....

Cheers
Ed
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: BruceM on June 18, 2018, 03:41:08 PM
Ed's first pass filtering should dramatically reduce total processing time and energy to the same quality output, for those that care about that aspect.  Nice bit of practical engineering, Ed.
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on June 18, 2018, 07:20:23 PM
Hi V,

While it will certainly clean the vast bulk of the debris, I, personally, am going a slightly different route in the bits I am getting together... I will be using a "fill tank" to dribble the oil through the fuge first time round to collect most of the junk... thereafter it will be a single tank system which will recirculate until shut down...

Hi Ed,

In a similar fashion, my raw oil will pass through a fine screen on the way into the single tank.
Everything else should get trapped by the centrifuge when subjected to 3000 G's (5000 rpm).

Based on the input from you fellas, I will proceed with a single tank system and see how it works out.

cheers,
Veggie
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on June 18, 2018, 07:31:49 PM
EdDee

Whilst I do not intend to run waste motor oil, there are many that do. Your centrifuge system should be a big help.
Here's what some are removing from their WMO...

https://www.youtube.com/watch?v=gCRXNTQgIv4 (https://www.youtube.com/watch?v=gCRXNTQgIv4)

https://www.youtube.com/watch?v=o0Hys3VPgl0 (https://www.youtube.com/watch?v=o0Hys3VPgl0)

keep us posted...
Veggie
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: AdeV on June 19, 2018, 08:19:04 AM
I started to make my own bowl using an old car brake drum... but I'm wondering if I shouldn't machine up an aluminium one from scratch... I'm concerned that the brake drum may not have enough strength to stay together at the sort of speeds I'm planning to rotate it.

Can I ask you a favour Veggie - how much does your bowl weigh, with lid? That's something else I'm contending with... the weight of the cast iron brake drum + a steel lid, might be a bit excessive...
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: glort on June 19, 2018, 11:50:11 AM

Not so much the weight you have to worry about Ade, it's the balance.
Mate and I played with this years ago.  We gave up. It's exacting stuff. You don't need much imbalance for things to go pear shaped fast.

Mate and I went to great lengths and trouble to do a washing machine Tub size unit. Fiberglass'ed it all up, had it balanced on a machine for doing gas turbine assembly's ( he worked in an aircraft factory)  and set it all up.  Spun the thing and it was perfect. We were chuffed.  Added oil, no problem, smooth as. We got it.  Did a batch of oil, all good. Thing held about 25L so like everything else we did, had huge reserve.

Ran 100L of oil and then shut it down. and the thing would down the 25L of oil slumped, the thing started shaking and 2 Seconds later literally self destructed.  Ripped itself and all our careful work to pieces.
braver men may have rebuilt it but ours weren't that big and round to tempt fate twice.

A mate bought one of the Rotor Type Fuges and we set that up for him and tested it and it wasn't that much of an advantage over our conventional processing so we let the fuge dream go.

Bowl type is definitely the way to go but they are expensive to buy and we didn't have the resources to machine one.  Not what you got in the aircraft factory, it's what Division the machines you need are in and if you know someone that runs it.  :0)

For a brake drum you could work out the rotational RPM at say 100 MPH and then spin the thing equivalent of say 150 with safety.  As long as the drum is in good Nick to start with and balanced, you should have no problems.

Fuges are time machines. They accelerate settling time of oil.  I was concerned about water as I was using veg oil and Fuges will not get that out so I just took the easy way out and settled the oil.
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on June 19, 2018, 02:17:46 PM
Can I ask you a favour Veggie - how much does your bowl weigh, with lid? That's something else I'm contending with... the weight of the cast iron brake drum + a steel lid, might be a bit excessive...

Hi AdeV, the spinning bowl does not have a lid.
Oil overflows the bowl and is caught in the outer chamber.
https://www.youtube.com/watch?v=PsLGX-RbKuQ (https://www.youtube.com/watch?v=PsLGX-RbKuQ)
The bow weighs about 5 lbs.
I got it here...
https://www.wvodesigns.com/rpc-poboy-kit.html.html (https://www.wvodesigns.com/rpc-poboy-kit.html.html)
It comes with a special taper lock hub which anchors it to a 5/8 shaft.

Hi Glort,
Fortunately the oil I get has very little water. (I trained them well  ;) )
However...there is always some water and my experience is that these types of centrifuges do a pretty good job of dewatering if the oil is hot enough.
In this example (not mine) you can see the steam leaving the processed oil ( at the 1:00 minute mark ).
https://www.youtube.com/watch?v=OksXHSWidMs (https://www.youtube.com/watch?v=OksXHSWidMs)
My unit has vapour ports in the lid and in the discharge line to channel moisture out.
1st generation fuges spin at 3600 rpm motor speed but with the use of 3 phase motors and variable frequency drives newer fuges can now run up to 6000 rpm making over 4000 g's. That really takes advantage of the sight specific gravity differences between water and oil. My thoughts are that multiple passes should eventually leave the oil quite dry, but until I run it ...I won't know for sure.

onward,
Veggie
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: AdeV on June 19, 2018, 08:17:09 PM

Not so much the weight you have to worry about Ade, it's the balance.

...

For a brake drum you could work out the rotational RPM at say 100 MPH and then spin the thing equivalent of say 150 with safety.  As long as the drum is in good Nick to start with and balanced, you should have no problems.


Balance - agreed... and I have no way to balance it other than statically, which is almost certainly not good enough... However.. my unit will be nowhere near 25l in capacity; that must have been a bloody monster of a machine!

I reckon the capacity of my brake drum, by the time you've added the centre spigot & lid, will be around 1.5-2 litres tops. It's about a foot/30cm across, if I recall correctly, and about 5"/12cm deep. I'd like to spin it as fast as humanly possible...

Assuming it used to live inside a 13" wheel (which seems about right, given its age), that would have had a 4 or 5" sidewall tyre fitted, so about 23" total rotational size, which is about 72" circumference (handy), or 6ft.

100mph is 8,800ft/min, so the brake drum is doing 1470rpm just about. So your safety margin gives me 2200rpm. I was hoping for at least 3600, and maybe even higher...

Next up - work out how many g's that is. That's beyond me tonight... I'll have a go tomorrow.


Anyway, as I wouldn't trust it not to explode at very high speeds, I intend to wrap it in a 5mm thick steel enclosure. I guess I should be able to calculate the centrifugal forces on the side of the bowl at a given RPM, then assume a 1lb lump flies off I can calculate the energy in that when it strikes the outer casing, which will tell me if I need to put a second 5mm steel ring around the inner one for protection purposes... although I might just do that anyway. Steel is a LOT cheaper than internal organs, and a damn site easier to replace...
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: glort on June 20, 2018, 01:41:31 AM

Get a brake Drum off an older Ferrari or something fast.
Should take a Higher RPM.   :0)
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: mike90045 on June 20, 2018, 05:11:39 AM
.... then assume a 1lb lump flies off I can calculate the energy in that when it strikes the outer casing, which will tell me if I need to put a second 5mm steel ring around the inner one for protection purposes.........

Once one lump flies off, I would assume the rest would follow in the next half second. So all the unbalanced drum will be shedding into your containment ring.   And if there is a spark and the oil is hot enough......
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: glort on June 20, 2018, 07:56:35 AM

 And if there is a spark and the oil is hot enough......

You'd still be shoving shit up hill trying to light it if you tried unless the oil is about 200oC which is not going to happen!
 Spent enough time trying to burn oil of all types to know!   :laugh:

That's the beauty of this stuff, it's pretty inert unless you really go to effort to get the stuff to burn.
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on July 07, 2018, 06:27:31 PM
UPDATE:

The project is slowly moving along.
I am now in the process of adding the circulation pump and interconnecting tubing.

Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on July 07, 2018, 06:29:27 PM
Inline oil heater made from a pipe with threaded connections welded in place.
1000 watt , 120 volt element.
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on July 07, 2018, 06:41:35 PM
PROBLEM !

I am using a small 12 volt gear pump to move the oil around.
It runs fine when connected directly to 12 volts, but my plan was to drive it with a 12 volt PWM motor speed controller so that I can finely control the flow rate of the oil through the centrifuge.
When I tested the PWM controller on this 12 volt pump, the pump ran at a fixed speed regardless of where I dialed the Pot on the PWM controller. After 15 seconds there was a lot of "Magic Smoke" coming out of the PWM controller. GAME OVER  :'(

(The PWM controller cost me $17 so it's not a big loss)

My question to the group is...
Any idea why this controller would run my 12VDC fertilizer sprayer pump at various speeds but then cook itself when trying to drive this 12 VDC gear pump. Both pumps use 4 amps and the PWM modulator is rated higher than that.

Could it be Brusless vs. Brush type ?
I would really like to be able to vary the speed on this Gear pump.
Any ideas?

Here is the pump... (not the same seller as I used but still the same pump)
https://www.ebay.ca/itm/12V-Scavenge-Gear-Pump-Diesel-Fuel-Scavenge-Oil-Transfer-US-FAST-SHIP-Black-Pump/151707363632?epid=1441247850&hash=item235276a930:g:mX4AAOSwIeFbMwqt (https://www.ebay.ca/itm/12V-Scavenge-Gear-Pump-Diesel-Fuel-Scavenge-Oil-Transfer-US-FAST-SHIP-Black-Pump/151707363632?epid=1441247850&hash=item235276a930:g:mX4AAOSwIeFbMwqt)

Here's the pump...
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: AdeV on July 07, 2018, 07:36:34 PM
Possibly the pump ended up drawing a much larger than rated current. I've got a similar pump, when I tried loading it up through a spray head, it shot over it's 4amp rating, I think it peaked at about 9 amps.

I'm not sure why those gear pumps are so much more expensive than similarly rated diaphragm pumps. In my experiments, the latter never went over their rated ampage,  and produced a far superior pressure. They're also capable of holding back mains pressure water, which simply sluices through a gear pump like it wasn't there...

(I know: Why bother with a pump when you've got mains water, right? Metering... and solenoid or motorised valves are far too slow acting when faced with a bar or so of mains water... stop the pump, the flow stops instantly).
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on July 07, 2018, 07:43:11 PM
Hi AdeV

When I tested the gear pump on the PWM controller it was not pumping liquid.
Just free wheeling and probably pulling only 1 amp.
Not sure why it would cook a controller. (Yes, I double checked the polarities  ;)  )

Veggie
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: BruceM on July 07, 2018, 08:08:12 PM
It seems unlikely to be a brushless 12 motor with integrated controller; they are more expensive at present.

I suspect that instead, you have an EMC problem with the cheap PWM controller and a nasty brushed motor, emi-wise. EMI from the motor is glitching the MOFET gate or gate controlling circuitry, thus you see full speed until failure.  Capacitors at the motor, and a common mode choke might solve it fairly cheaply. A better designed PWM controller might be able to handle it. If your 12V supply is also full of EMI, that should also be addressed via passive filtering since the controller may not handle that well either.

MOSFETs have amazingly low "on" resistance so can handle a huge load in a single small package.  They do have some serious issues with EMI; their gates are voltage controlled and are much more susceptable to glitching than older bipolar transistors which are current controlled. 

The solution to avoid glitching is suppression at the source (motor), but also to use a very low resistance gate drive (1-10 ohm). Many cheap electronics will not in order to save cost.

Solving the problem at the source is a cost effective solution as it prevents the same EMI from damaging or cause intermittent faults of other connected electronics.  For a "junk box" filter for this motor, I'd start with 0.0-1 uF ceramic, and 10-100 uF electrolytic, and a 3+ mH common mode choke rated for your max current or better. 
 
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: glort on July 08, 2018, 01:43:14 AM

.... And when all the oil is cleaned, you are going to rent the thing out to movie producers as a prop for the new Dr. Who movie they are Making Right?   :laugh:

As for the pump, those things had a poor reputation with pumping Veg oil here at least.  Always under performing in longevity or output.  I also see something that would put me off using them in this application if I were ever inclined.....
Designed for intermittent use only. Duty cycle: 30 mins

I would be using a mains powered AC motor/ pump for sure.  Even just the little chinese QB type pumps would be far better than one of these IHMO.  Mate used them on his Bio making setup and we ran hundreds of hours on them with no problem. You need 240 for the heater so may as well run the pump off the mains as well.

What power supply were you running the PWM/ motor off? Was it a battery or some sort of Plug pack/ Ac to DC converter?  If it was a converter, maybe the output was just too Dirty and that's what upset the PWM?

I would really encourage the use of a heavier duty mains powered pump./ You can get PWM's for those as well.  I have had one regulating my 3.6 KW Hot water heater  for months and not had a problem with it yet.

https://www.ebay.ca/itm/Hanchen-Instrument-Electric-Clean-Water-PUMP-110v-220v-QB-60/382512186313?hash=item590f80c3c9:g:qeIAAOSwESNZ92tZ
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on July 08, 2018, 01:52:51 AM
BruceM

Thanks for that detailed explanation of the potential problem at hand.
The power source is a 12 volt deep cycle battery. Clean power.
I suspect poor Chinese electronics (again). In any case, it's dead. I won't be buy another anytime soon.
What do you think about using a Rheostat with an adequate amperage rating.?
Just vary the voltage instead of PWM.

Veggie
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on July 08, 2018, 02:04:49 AM
Hi Glort,

Ha...Ha. Yes Dr. Who was inquiring. It's a Tardis machine. It actually holds 3000 liters of WVO but it looks very tiny.  ;D

I have one of those pumps that you mentioned (330 gallons per hour). I use it on my BioD processor for circulation, but for this application the feed to the centrifuge is only 10 gallons per hour. Just a trickle.
That's why I was hoping to slow down the gear pump a bit.

I will dig around more to see if I can come up with a better pump running off mains power.
The centrifuge and pump will have to run for 3 hours per batch so I need a small pump that can handle that duty time.

Perhaps for the time being I can run this gear pump at normal speed with a bypass valve in the discharge line which can slip some of the flow back to the tank. I could adjust the bypass valve position until I get the desired flow rate into the Fuge.
The WVO is open circulation from the tank to the Fuge (no pressure) so maybe the pump will last a bit longer without pressure/amperage stresses.

cheers
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: BruceM on July 08, 2018, 03:14:44 AM
If adding a filter is too much for you, then yes,  a power resistor to drop the voltage could be used.  Let ohm's law be your guide for value and watt rating. 

Title: Re: WVO Centrifuge Design - thoughs ?
Post by: glort on July 08, 2018, 04:00:28 AM
It's a very good looking and beautifully presented machine that's for sure.
I don't think I have ever painted anything I have done like that.  I have always been of the opinion if it worked that was good enough. I am trying to come around though and make things look more presentable. I don't know why I never have taken more pride in what I have done before.
Messy mind, messy machinery I guess.  :embarassed:


The WVO is open circulation from the tank to the Fuge (no pressure) so maybe the pump will last a bit longer without pressure/amperage stresses.


I think that has a lot to do with Duty Cycle. The more under stressed a motor is the longer the heat build up takes and may dissipate it  completely.
Running a resistor should work, my favorite for 12V is just light bulbs. Limiting the current below the motors rating will also mean it can run at lower volts without having heat build up due to higher Current.

I use the 24V electric scooter motors on a modified Chev Small block oil pump for oil collection.  If I run the thing at 24V it will heat up after about 4-500L.  The thing still pushes about 70% flow at half voltage.  If I run it of 12V I can get 1000L through it and it's still fine.

If this were a centrifugal pump you could just limit the inlet and it will reduce the motor load as well. being a gear pump and positive displacement, any limitation would make the motor labor significantly.  My Chev gear pump will stall a 3HP petrol motor of you block it OR simply burst a hose or connection.
I tweaked the pump right up internally with clearances so it does max flow and pressure.  The by pass is also blocked so it only be reduced in output by slowing the drive speed. Yours will be much the same even as is and not possible to slow flow rate only the drive.

Bulbs are good resistors as you also get an indication of the current flow and you can parallel or series them or switch them in and out for different speeds and they never over heat.

The thing with these 12V motors is they tend to run plain bearing and brushes are are just not good logging up decent run hours. AC motors generally have ball races and can run 24/7 for years at a time.  A low voltage motor capeable of the same endurance will cost more than an AC motor would anyway.

What temp are you going to run your oil at?  I used to run mine in my processor up to 80C to speed up the drying process.  I limited it to that as I was worried about heat going back to the motor but mainly the softening of the hoses I was using and the filter being rated to much less than that.  never had a problem with it though. I used a veg oil burner so I was able to heat it fast. Once up to temp I let it run from there. Time it got to 50 the oil was well filtered and dried and ready to put into the clean tanks.

To aid drying I had a fan SUCKING air out the tank. I tried blowing into the tank and curiously, it was as bad as having no air circ at all.  If You could have an open section to your system where the moisture could evaporate, you would be able to dry at the same time.  As fuges don't inherently do that, it was one reason I stuck to settling  and filtering. 

Have to go start collecting some oil again soon.
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on July 08, 2018, 04:10:00 AM

All good ideas Glort. Thanks.
Yes, there is an open steam port of the lid of the unit. I will report back on how effective that is.
The planned temperature for oil entering the Fuge is 80C.

BruceM, I will look into sizing a heavy duty resistor for dropping the voltage (speed) to something usable.
Maybe a light bulb or two as Glort suggested as an initial test.

Updates to follow...
Veggie
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: BruceM on July 08, 2018, 05:18:25 AM
I also use 12V light bulbs for power resistors, I've got 15, 25 and 50 watt bulbs in standard lamp bases. Walmart carries the 50 watt ones.  I also have a 30 year collection of power resistors left over from various projects, and where I guessed wrong on value.  Adjustable ceramic wire wound unit's in fairly high wattages are very handy...Digikey carries those.

I like induction motors, too, for something like this. A brushed DC motor on a load resistor will vary in speed with load.





Title: Re: WVO Centrifuge Design - thoughs ?
Post by: AdeV on July 08, 2018, 12:04:32 PM
BruceM, I will look into sizing a heavy duty resistor for dropping the voltage (speed) to something usable.
Maybe a light bulb or two as Glort suggested as an initial test.

Why not see if you can get a blower fan speed controller from a scrap car? Certainly in older cars, these were simply resistor packs wired in series with the blower motor... If you can find a 3- or 4-speed one, then you've got a realtime speed control system AND a natty dashboard :D
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: glort on July 08, 2018, 01:26:18 PM

Good idea but be aware that the resistor is generally in the blower housing and is a flat unit that sits in the airstream for cooling.
You'll want the resistor the switch and at least the ends of the wiring harness they connect to.

Newer cars ( up to 10 YO) can have 3 phase blower motors and are controlled by a PWM from the computer or a separate control box.  Your best bet will be something 10 yrs+ .
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: veggie on July 22, 2018, 10:46:46 PM
** UPDATE **

I decided to go with mechanical flow control since I had most of the bits and pieces in my box of fittings.
The gear pump now has a discharge bypass which can relieve flow back to the suction side of the pump.
The RED valve lever controls flow. The gear pump can run at it's rated speed for the rest of it's life. (which according to Glort may not be for very long  ;) )
The unit is almost ready to fire up.
Next is to mount the centrifuge motor variable frequency drive in a box to hide the 240 volt connections.
I may also add a switch on the front of the box to allow for quick power kill.

Here's the  latest...

Title: Re: WVO Centrifuge Design - thoughs ?
Post by: EdDee on July 22, 2018, 11:36:45 PM
Hey Veggie,

A little trick I often pull with pumps is to use a regular water type stopcock type tap/valve in place of your ball valve to prevent overpressuring and stalling the pump....

You mod the stopcock by removing the rubber washer and then placing a fairly strong spring between the spindle and the seal holder... As you screw the tap closed, the spindle pushes the seal holder onto the seat and increases system pressure... this allows you to adjust flow later on in the line without stalling the pump... A full seal is not required in this application, hence the removal of the rubber washer

Just a thought...

Cheers
Ed
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: BruceM on July 22, 2018, 11:47:22 PM
Nice tip, Ed.  Veggie, does your gear pump already have an overpressure bypass relief internally built in?  If so, no worries on the ball valve.  Ball valves are great- but not so great for flow regulation near the low end, so Ed's solution solves both blowout and regulation adjust- assuming you have the right force spring.
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: ajaffa1 on July 22, 2018, 11:51:10 PM
Hi Veggie, been watching your build with great interest. Nice work and great paintwork.
I run a couple of VFD  controllers in my joinery shop. Please be aware that they have internal cooling fans and create a lot of heat under heavy loads or long runs. You will need to cut some ventilation holes in your enclosure or things will go bang. Please don`t ask me how I know or how much it cost.
Here in Australia we have problems with mud wasps and other creepy crawlies that love to get into electrical enclosures so I now cover all ventilation slots/holes with fly screen mesh, have to blow the dust out of them regularly.

Looking forward to seeing it running,
Bob
Title: Re: WVO Centrifuge Design - thoughs ?
Post by: AdeV on July 23, 2018, 08:18:47 PM
If it's anything like my cheap* Chinese gear pump - and it looks identical - it won't need an over-pressure or bypass system: the gears mesh so badly it'll just start spinning the oil if the back pressure's too much for it. Beware it's power consumption, though, which will soar above it's rated value and will cause overheating and damage in next to no time.

It's also hopeless if there's any pressure behind it: The oil/fluid will simply push past the gears and through the outlet pipe. A valve of some kind immediately before the pump would be a wise move, unless it's specifically lifting the working fluid against gravity, in which case you'll be fine (but it'll lose prime every single time you stop it; not a problem if you're not lifting more than about 6ft, as it will self-prime readily enough).

You may be getting the impression I'm a bit unimpressed with my gear pump.  ::)

* Not that cheap either... about 3x the price of a diaphragm pump of slightly lower rating which - in practice - performed better with a lower electrical load.