i have in mind a project which would require some medium amount of
centrifuging batches of materials. Industrial centrifuges are too
expensive.

I thought to start with a washing machine, it's a decent volume of spun
space, and they are relatively cheap.

Anything even better? Willing to spend as long as
results/incremental-dollars margin is positive.

wrote:
i have in mind a project which would require some medium amount of
centrifuging batches of materials. Industrial centrifuges are too
expensive.

I thought to start with a washing machine, it's a decent volume of spun
space, and they are relatively cheap.

Anything even better? Willing to spend as long as
results/incremental-dollars margin is positive.


You might be surprised how cheap a 'real' centrifuge can be had.
I bought a couple large ones at a Silicon Valley auction for $20 for the
pair. I sold them for more than that, but ebay has all kinds of them for
pretty cheap. About what you'd pay to setup a washing machine that
won'yt realy spin at a very good speed.
http://search.ebay.com/centrifuge

Cheers,
- JJG

In article . com,
says...
i have in mind a project which would require some medium amount of
centrifuging batches of materials. Industrial centrifuges are too
expensive.

I thought to start with a washing machine, it's a decent volume of spun
space, and they are relatively cheap.

Anything even better? Willing to spend as long as
results/incremental-dollars margin is positive.


What on earth do you want a centrifuge for w.r.t. homebrewing?
I've done it for years without ever seeing the need, and we have two
boutique breweries around, one in the valley and one in the village and
neither of them ever owned a centrifuge (nor do the large commercial
German breweries I've visited)?!?

-P.

--
=========================================
firstname dot lastname at gmail fullstop com

I don't think he was going to use the centerfuge for making beer.
"Homebrew" seems to be used as a synonym for homemade.


"Peter Huebner" wrote in message
t...
In article . com,
says...
i have in mind a project which would require some medium amount of
centrifuging batches of materials. Industrial centrifuges are too
expensive.

I thought to start with a washing machine, it's a decent volume of spun
space, and they are relatively cheap.

Anything even better? Willing to spend as long as
results/incremental-dollars margin is positive.


What on earth do you want a centrifuge for w.r.t. homebrewing?
I've done it for years without ever seeing the need, and we have two
boutique breweries around, one in the valley and one in the village and
neither of them ever owned a centrifuge (nor do the large commercial
German breweries I've visited)?!?

-P.

--
=========================================
firstname dot lastname at gmail fullstop com

In article ,
says...
I don't think he was going to use the centerfuge for making beer.
"Homebrew" seems to be used as a synonym for homemade.


Oh dear. A blonde moment ?!?

Lol, -Peter

--
=========================================
firstname dot lastname at gmail fullstop com

Keep YerSpam wrote:
wrote:

i have in mind a project which would require some medium amount of
centrifuging batches of materials. Industrial centrifuges are too
expensive.

I thought to start with a washing machine, it's a decent volume of spun
space, and they are relatively cheap.

Anything even better? Willing to spend as long as
results/incremental-dollars margin is positive.


You might be surprised how cheap a 'real' centrifuge can be had.
I bought a couple large ones at a Silicon Valley auction for $20 for the
pair. I sold them for more than that, but ebay has all kinds of them for
pretty cheap. About what you'd pay to setup a washing machine that
won'yt realy spin at a very good speed.
http://search.ebay.com/centrifuge

That's true. A friend of mine has picked up four for nothing from
science labs recently. I think 3 out of the 4 worked okay. They were
scary 10,000 rpm machines, too, but only had a fairly small capacity.

Chris

What on earth do you want a centrifuge for
w.r.t. homebrewing?
I've done it for years without ever seeing the
need, and we have two
boutique breweries around, one in the valley and
one in the village and
neither of them ever owned a centrifuge (nor do
the large commercial
German breweries I've visited)?!?

We had two, 100 Hp centrifuges at a brewery that
I worked at In Sydney. We used them to spin out
most of the yeast before the beer was filtered. It
save a significant amount of money in diatomaceous
earth filter powder as well as saving on the
disposal costs of used filter medium..
They frightened hell out of me. The rotor weighed
about 100 Kg and spun at 300 rpm. . They used an
eddy current drive to get it up to speed. It took
over an hour to get to operating speed from cold
start.

I did a "back of an envelope' calculation with
regard to the stored energy in one of these
things,and avoided them like the plague ever
since.

Tom Miller

Tom Miller wrote in message
...


What on earth do you want a centrifuge for
w.r.t. homebrewing?
I've done it for years without ever seeing the
need, and we have two
boutique breweries around, one in the valley and
one in the village and
neither of them ever owned a centrifuge (nor do
the large commercial
German breweries I've visited)?!?

We had two, 100 Hp centrifuges at a brewery that
I worked at In Sydney. We used them to spin out
most of the yeast before the beer was filtered. It
save a significant amount of money in diatomaceous
earth filter powder as well as saving on the
disposal costs of used filter medium..
They frightened hell out of me. The rotor weighed
about 100 Kg and spun at 300 rpm. . They used an
eddy current drive to get it up to speed. It took
over an hour to get to operating speed from cold
start.

I did a "back of an envelope' calculation with
regard to the stored energy in one of these
things,and avoided them like the plague ever
since.

Tom Miller

That's a lot less energy than an average IC engine spinning at 6k rpm so I'm
not sure what you are so frightened about.
--
Dave Baker

Depends upon what you expect from the centrifuge.
If you intend to clean up waste vegetable oil with it, you might look for
a cream separator as used in a dairy.

If you project can be solved by filtration, it might be cheaper and easier
to fabricate from available junk.

"Tom Miller" wrote in message
...


What on earth do you want a centrifuge for w.r.t. homebrewing?
I've done it for years without ever seeing the need, and we have two
boutique breweries around, one in the valley and one in the village and
neither of them ever owned a centrifuge (nor do the large commercial
German breweries I've visited)?!?

We had two, 100 Hp centrifuges at a brewery that I worked at In Sydney. We
used them to spin out most of the yeast before the beer was filtered. It
save a significant amount of money in diatomaceous earth filter powder as
well as saving on the disposal costs of used filter medium..
They frightened hell out of me. The rotor weighed about 100 Kg and spun at
300 rpm. . They used an eddy current drive to get it up to speed. It took
over an hour to get to operating speed from cold start.

I did a "back of an envelope' calculation with regard to the stored energy
in one of these things,and avoided them like the plague ever since.

Tom Miller



Is this RPM right? 220 lbs. at 300 RPM just doesn't seem all that dangerous
to me. How much weight was spinning when it was loaded?

Garrett Fulton

wrote:
i have in mind a project which would require some medium amount of
centrifuging batches of materials. Industrial centrifuges are too
expensive.

I thought to start with a washing machine, it's a decent volume of spun
space, and they are relatively cheap.

Anything even better? Willing to spend as long as
results/incremental-dollars margin is positive.

It would help a lot if you described what you were doing. Are you
separating materials by forcing them through a sieve, or what.

On Thu, 27 Oct 2005 10:21:22 +0100, with neither quill nor qualm,
"Dave Baker" quickly quoth:

Tom Miller wrote in message
I did a "back of an envelope' calculation with
regard to the stored energy in one of these
things,and avoided them like the plague ever
since.

That's a lot less energy than an average IC engine spinning at 6k rpm so I'm
not sure what you are so frightened about.

Are you sure, Dave? The forces at such a larger radius and such a
larger mass at 300 RPM would seem to have a lot more energy than an
average IC engine could put out. (I'd like to see figures on both for
S&G. Throw in 1,500hp funny car/dragster engine figs, too, please.)

My truck's V-8 engine is spinning at an angle which would not slice
and dice me if it blew. (Although the new small cars with transverse
engines have their radial mass trajectories (what's the correct term
for this?) "aimed" more toward you, they have considerably less mass
to throw atcha.)

LJ--who doesn't recall hearing the term "centripetal" before this
newsgroup and has zero college math under his belt.

--
SAVE THE PARROTS! Eschew the use of poly!
----------
http://diversify.com Poly-free Website Development

In article , says...
We had two, 100 Hp centrifuges at a brewery that
I worked at In Sydney. We used them to spin out
most of the yeast before the beer was filtered. It
save a significant amount of money in diatomaceous
earth filter powder as well as saving on the
disposal costs of used filter medium..

/rant on
That's more or less what I had in mind when I asked. Where I come from,
you don't use either centrifuges nor diatomaceous earth filters. You
don't use finings, you don't use uv to age the beer (you bloody well age
it in the tank first, and in the bottle second - 3 months minimum for
the latter before the bottles are allowed out the gate). I know very
well that the 'brewers' down here can't be bothered with that, and
that's why I won't buy DB or Lion or Foster etc ... I drink my own or
imported European beers.
I stopped drinking Tuborg and Stella the moment they started making it
in NZ under license, because I can taste the difference. :-( At times I
have the feeling they use cats' kidneys in the filtration process,
that's why they have to drink it ice cold: so they can't taste it.

Brewing beer should be an organic process, i.m.o. and not a chemistry
experiment. Patience pays off. Of course, that only applies if you take
pride in the product rather than just chasing the dollars.

Guess I'm just an old fusspot /rant off -P.

--
=========================================
firstname dot lastname at gmail fullstop com

Peter Huebner wrote:

In article ,
says...

I don't think he was going to use the centerfuge for making beer.
"Homebrew" seems to be used as a synonym for homemade.



Oh dear. A blonde moment ?!?

Lol, -Peter


I was going to say somthing about how yours must be REALLY good
home-brew... ;-)

When you get to making ones own stil let me know....

On Thu, 27 Oct 2005 08:55:28 -0400, "gfulton"
wrote:


"Tom Miller" wrote in message
...


What on earth do you want a centrifuge for w.r.t. homebrewing?
I've done it for years without ever seeing the need, and we have two
boutique breweries around, one in the valley and one in the village and
neither of them ever owned a centrifuge (nor do the large commercial
German breweries I've visited)?!?

We had two, 100 Hp centrifuges at a brewery that I worked at In Sydney. We
used them to spin out most of the yeast before the beer was filtered. It
save a significant amount of money in diatomaceous earth filter powder as
well as saving on the disposal costs of used filter medium..
They frightened hell out of me. The rotor weighed about 100 Kg and spun at
300 rpm. . They used an eddy current drive to get it up to speed. It took
over an hour to get to operating speed from cold start.

I did a "back of an envelope' calculation with regard to the stored energy
in one of these things,and avoided them like the plague ever since.

Tom Miller



Is this RPM right? 220 lbs. at 300 RPM just doesn't seem all that dangerous
to me. How much weight was spinning when it was loaded?


It depends on the size of the 'fuge. With a 10 ft dia 'fuge,
tangential velocity at 300 RPM is 157 ft/sec or about 107 mph with
about 150 G's on the load -- so the 220 lb mass is straining to leave
the bucket with 33,000 lb of force if I did me sums right.

I once saw a $20K (1966 dollars) electrostatically-suspended gyro fly
thru the 'fuge housing, go about 30 feet and then thru a brick wall.
There were no pieces larger than a nickel left. I think that one only
went up to 100 G's.

"Dave Baker" writes in article dated Thu, 27 Oct 2005 10:21:22 +0100:

Tom Miller wrote in message
...
They frightened hell out of me. The rotor weighed
about 100 Kg and spun at 300 rpm. . They used an
eddy current drive to get it up to speed. It took
over an hour to get to operating speed from cold
start.

I did a "back of an envelope' calculation with
regard to the stored energy in one of these
things,and avoided them like the plague ever
since.

Tom Miller

That's a lot less energy than an average IC engine spinning at 6k rpm so I'm
not sure what you are so frightened about.
--
Dave Baker

Tom didn't give us enough numbers to calculate energy. The energy of a
spinning hollow cylinder is (1/2)*mass*(radius*angular_velocity)^2. What
was the radius of the rotor, Tom?

The mass of the moving parts in a car engine is much less than 100kg, and
the radii are probably also much less -- radius of the crank and cam, and
half the stroke length for the pistons, which is a high-ball estimate
because the pistons only move at (radius*angular_velocity) in the middle of
their stroke.

-- spud_demon -at- thundermaker.net
The above may not (yet) represent the opinions of my employer.

"Dave Baker" wrote in message
...

Tom Miller wrote in message
...


What on earth do you want a centrifuge for
w.r.t. homebrewing?
I've done it for years without ever seeing the
need, and we have two
boutique breweries around, one in the valley and
one in the village and
neither of them ever owned a centrifuge (nor do
the large commercial
German breweries I've visited)?!?

We had two, 100 Hp centrifuges at a brewery that
I worked at In Sydney. We used them to spin out
most of the yeast before the beer was filtered. It
save a significant amount of money in diatomaceous
earth filter powder as well as saving on the
disposal costs of used filter medium..
They frightened hell out of me. The rotor weighed
about 100 Kg and spun at 300 rpm. . They used an
eddy current drive to get it up to speed. It took
over an hour to get to operating speed from cold
start.

I did a "back of an envelope' calculation with
regard to the stored energy in one of these
things,and avoided them like the plague ever
since.

Tom Miller

That's a lot less energy than an average IC engine spinning at 6k rpm so
I'm
not sure what you are so frightened about.
--
Dave Baker


Wouldn't that depend a lot on the rotor diameter? The further out you move
that 100Kg from the center the faster it will be moving at 300RPM. It seems
to me like we could be talking about a LOT of energy. Especially considering
it takes a 100HP motor over an hour to spin it up!
Bob

Bob wrote:

...we could be talking about a LOT of energy. Especially considering
it takes a 100HP motor over an hour to spin it up!

100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-)

Nick

i have in mind a project which would require some medium amount of
centrifuging batches of materials. Industrial centrifuges are too
expensive.

I thought to start with a washing machine, it's a decent volume of spun
space, and they are relatively cheap.


What's wrong with a bucket on a rope?

...we could be talking about a LOT of energy. Especially considering
it takes a 100HP motor over an hour to spin it up!

100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-)

About 1530 pounds, ie 1.5 kilotons.

Nick

Larry Jaques wrote:

LJ--who doesn't recall hearing the term "centripetal" before this
newsgroup and has zero college math under his belt.

Aw yes! That is always a good starter for a LOOOOng thread. :-)]
Watch you have done Larry.
...lew...

wrote:

100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-)

About 1530 pounds, ie 1.5 kilotons.
*****
Nick

Come again Nick ? a ton is 2000 pounds.
...lew...

On 27 Oct 2005 16:34:38 -0400, wrote:

...we could be talking about a LOT of energy. Especially considering
it takes a 100HP motor over an hour to spin it up!

100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-)

About 1530 pounds, ie 1.5 kilotons.

Nick

A ton is 2000 lb so your figures suggest 0.75 KT.

It is very unlikely that the motor was delivering 100 HP to
acceleration for even an appreciable part of that time.
If the cetrifuge were a 100 G 'fuge running at 300 RPM the energy
would be about 49,000 joules. That's about the kinetic energy of a
2500 lb automobile travelling at 21 mph. The 100 kg mass in the
'fuge would have a tangential velocity of about 70 mph.

It can be misleadingly dramatic to cite energy in terms of tons (or
pounds) of TNT (or dynamite). Propane has about 10X the energy per
lb that TNT does. TNT just releases it more suddenly.

Don Foreman wrote:
On 27 Oct 2005 16:34:38 -0400, wrote:
....
About 1530 pounds, ie 1.5 kilotons.

A ton is 2000 lb so your figures suggest 0.75 KT.
....

No - .75 ton or .00075 KT

100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-),
About 1530 pounds, ie 1.5 kilotons

Erm, it would doubtless be "killa" if you were standing nearby at the
time of an uncontained failure but it isn't "kilo" (1.5 kT = 3 million
pounds, said of the blast aspect of nuclear weapons in broad comparison
to TNT).

I also think the amount of time needed to spin it up is irrelevant to
a calculation of how much rotational kinetic energy it has when done
(though perhaps highly relevant to how much energy will drain out of
you when you get the electric bill!); and that's the key fact for
safety.

BTW, I think the energy use is 268 MJ, not 3 GJ, if you run a 100 hp
(input) motor for an hour. Check my logic... A horsepower is 745 W.
A watt is a joule per second, so if you do that for 3600 seconds you
get 268,200,000 joules.

See for instance
http://www.newton.dep.anl.gov/askasc...9/phy99x45.htm
and (one of the most eminently bookmarkworthy and explorable sites
around)
http://hyperphysics.phy-astr.gsu.edu/hbase/rke.html

--Joe "Whatever the numbers, centrifuges are built strong, and operated
according to safety instructions, for a reason" Chew

Ad absurdum per aspera wrote:
100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-),

About 1530 pounds, ie 1.5 kilotons

Erm, it would doubtless be "killa" if you were standing nearby at the
time of an uncontained failure but it isn't "kilo" (1.5 kT = 3 million
pounds, said of the blast aspect of nuclear weapons in broad comparison
to TNT).

I also think the amount of time needed to spin it up is irrelevant to
a calculation of how much rotational kinetic energy it has when done
(though perhaps highly relevant to how much energy will drain out of
you when you get the electric bill!); and that's the key fact for
safety.

BTW, I think the energy use is 268 MJ, not 3 GJ, if you run a 100 hp
(input) motor for an hour. Check my logic... A horsepower is 745 W.
A watt is a joule per second, so if you do that for 3600 seconds you
get 268,200,000 joules.

Assuming you lose nothing to friction during that hour of the giant
heavy drum spinning.

- Logan

Sure enough... that's why I took the liberty of specifying "100 hp
(input"). That may not have answered quite exactly the question asked,
but lends itself to doing a finite-envelope model without having to
look around in the bottom drawer for another envelope.

Accounting for real-world efficiency, the actual power usage curve, and
other things you'd want to tease out if you were designing or
specifying equipment, rather than just getting a quick calculation onto
the right order of magnitude, makes for big equations with a lot of
moving parts.

Cheers,
--Joe

Ad absurdum per aspera wrote:
Accounting for real-world efficiency, the actual power usage curve, and
other things you'd want to tease out if you were designing or
specifying equipment, rather than just getting a quick calculation onto
the right order of magnitude, makes for big equations with a lot of
moving parts.

Agreed. I was just trying to imply that an hour's worth of friction
might change the energy by an entire order of magnitude.

On the other hand, if it truly takes an hour to get up to speed,
then maybe friction is only a small part of the battle...

- Logan

radial mass trajectories (what's the correct term
for this?)


Tangential

On Thu, 27 Oct 2005 21:37:10 GMT, with neither quill nor qualm, Lew
Hartswick quickly quoth:

Larry Jaques wrote:

LJ--who doesn't recall hearing the term "centripetal" before this
newsgroup and has zero college math under his belt.

Aw yes! That is always a good starter for a LOOOOng thread. :-)]
Watch you have done Larry.
...lew...

GOTCHA!

--
SAVE THE PARROTS! Eschew the use of poly!
----------
http://diversify.com Poly-free Website Development

In article et,
Lew Hartswick wrote:
wrote:

100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-)

About 1530 pounds, ie 1.5 kilotons.
*****
Nick

Come again Nick ? a ton is 2000 pounds.
...lew...

Small kilotons :-) One site says 100 grams of dynamite is 0.43x10^6 joules.

Nick

On Thu, 27 Oct 2005 20:47:15 GMT, Ignoramus21002
wrote:

On 27 Oct 2005 16:34:38 -0400, wrote:
...we could be talking about a LOT of energy. Especially considering
it takes a 100HP motor over an hour to spin it up!

100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-)

About 1530 pounds, ie 1.5 kilotons.

???


Nick

..75 kt

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

Logan Shaw wrote:
Ad absurdum per aspera wrote:

Accounting for real-world efficiency, the actual power usage curve, and
other things you'd want to tease out if you were designing or
specifying equipment, rather than just getting a quick calculation onto
the right order of magnitude, makes for big equations with a lot of
moving parts.


Agreed. I was just trying to imply that an hour's worth of friction
might change the energy by an entire order of magnitude.

On the other hand, if it truly takes an hour to get up to speed,
then maybe friction is only a small part of the battle...

- Logan
There is no friction.An eddy current drive would be magneticly coupled.

On Fri, 28 Oct 2005 18:33:17 -0800, MK1 wrote:

Logan Shaw wrote:
Ad absurdum per aspera wrote:

Accounting for real-world efficiency, the actual power usage curve, and
other things you'd want to tease out if you were designing or
specifying equipment, rather than just getting a quick calculation onto
the right order of magnitude, makes for big equations with a lot of
moving parts.


Agreed. I was just trying to imply that an hour's worth of friction
might change the energy by an entire order of magnitude.

On the other hand, if it truly takes an hour to get up to speed,
then maybe friction is only a small part of the battle...

- Logan
There is no friction.An eddy current drive would be magneticly coupled.

The energy difference between what the motor supplies and what the
load absorbs is dissipated as heat in the eddy current clutch. Just
like a friction clutch would except that there are no wearing
surfaces.

At the instant of startup, the drive is dissipating all the power and
the load is absorbing none. At the instant of full speed, the load is
absorbing all the power and drive is dissipating none. (This assumes
no electronic ramp drive to the eddy current clutch) The actual
solution to the stored energy problem is a nice little calculus
problem but one can approximate by assuming that half is dissipated
and half absorbed by the load. That's a spit-load of energy! I'd
certainly not want to be in the building if the rotor disassembled
itself.

John

---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN

In article ,
wrote:
Bob wrote:

...we could be talking about a LOT of energy. Especially considering
it takes a 100HP motor over an hour to spin it up!

100HPx746Wx3600s = 3 billion joules. How much is that in dynamite? :-)

Nick


I believe it is a couple hundred sticks of the stuff, maybe a whole ton
of it. Although, it is the frissance of the dynamite, not the energy
that makes it dangerous. Your typical chocolate chip cookie contains
more chemical energy than a stick of dynamite. About the only way to
fully realize this is to notice how flour, with an incendiary trigger,
can make an adequite fuel air explosive.

Richard Bell wrote:

Your typical chocolate chip cookie contains
more chemical energy than a stick of dynamite.

Which is just the say the cookie not only tastes great, it has less
filler