HI! I need a capillary wicking medium that's durable, rigid and comes
in ~1/4" diameter rods. The cheaper the better.
How do borosilicate rods sound?
Pyrex doesn't wick. A thin bat of 5 micron Pyrex glass wool pulled
into a Pyrex tube would in a be pretty good. You can buy porous
ceramic or Vycor pre-form rods, ditto sintered metal rods.
Macroreticular carbon might come small enough. Possibly open-cell
polyimide foam.
Depends on what it has to survive. Can you use square rods? Cut
sheet,
<http://www.porvairfiltration.com/view_cat.php?i=68&s=&c=70>
http://www.porex.com/english/porous/pplastics.asp
<http://www.thomasregisterdirectory.com/plastic_materials/porous_plastics_0022037_1.html>
google
porous metal 193,000 hits
into a Pyrex tube would in a be pretty good. You can buy porous
ceramic or Vycor pre-form rods, ditto sintered metal rods.
Macroreticular carbon might come small enough. Possibly open-cell
polyimide foam.
Depends on what it has to survive. Can you use square rods? Cut
sheet,
<http://www.porvairfiltration.com/view_cat.php?i=68&s=&c=70>
http://www.porex.com/english/porous/pplastics.asp
<http://www.thomasregisterdirectory.com/plastic_materials/porous_plastics_0022037_1.html>
porous metal 193,000 hits
QUOTE (Uncle Al+Apr 17 2004, 03:59 PM)
Pyrex doesn't wick. A thin bat of 5 micron Pyrex glass wool pulled
into a Pyrex tube would in a be pretty good. You can buy porous
ceramic or Vycor pre-form rods, ditto sintered metal rods.
Macroreticular carbon might come small enough. Possibly open-cell
polyimide foam.
I don't think you will get Pyrex glass wool, but you can get silica wool,
which is leached borosilicate in a form which behaves like Vycor and
disproportionates into two continuous phases. Acid leaches out the alkali
borate, leaving the silica skeleton.
into a Pyrex tube would in a be pretty good. You can buy porous
ceramic or Vycor pre-form rods, ditto sintered metal rods.
Macroreticular carbon might come small enough. Possibly open-cell
polyimide foam.
I don't think you will get Pyrex glass wool, but you can get silica wool,
which is leached borosilicate in a form which behaves like Vycor and
disproportionates into two continuous phases. Acid leaches out the alkali
borate, leaving the silica skeleton.
QUOTE (Terry Harper+Apr 17 2004, 03:59 PM)
I don't think you will get Pyrex glass wool, but you can get silica wool,
which is leached borosilicate in a form which behaves like Vycor and
disproportionates into two continuous phases. Acid leaches out the alkali
borate, leaving the silica skeleton.
5 micron diameter filament Pyrex glass wool is sold in 5 lb bats.
Vycor pre-forms have ca. 50 nm connected pores. It depends on what he
is wicking, how much mass transport he needs, cleanliness of the fluid
re particulates and microrganisms (glycocalyx, biolslime, cells,
hyphae, precipitates), how chemically agressive the stuff is... and it
has to be cheap.
Glass wool pulled through a section of Pyrex tubing is cheap, strong,
and survivable (but not to alkali). Plastic foam is cheaper. Vycor
preforms are pricey. Engineer to use the stuff if you can. Don't do
the design first and then pursue availability of a miracle material.
We see this micromanagerial crap all the time in medical devices.
Biocompatiblity is only surface deep. The bulk material doesn't have
to be biocompatible, it simply has to omit any objectionable
breakthrough or blooming. Especially for acute exposure use once and
toss, you lay down an expensive micron over a really cheap inch that
meets all other specs. Surgical adhesions need *never* happen if
latex gloves are surface grafted with a micron of PVP. Who gives a
damn about the patient?
which is leached borosilicate in a form which behaves like Vycor and
disproportionates into two continuous phases. Acid leaches out the alkali
borate, leaving the silica skeleton.
5 micron diameter filament Pyrex glass wool is sold in 5 lb bats.
Vycor pre-forms have ca. 50 nm connected pores. It depends on what he
is wicking, how much mass transport he needs, cleanliness of the fluid
re particulates and microrganisms (glycocalyx, biolslime, cells,
hyphae, precipitates), how chemically agressive the stuff is... and it
has to be cheap.
Glass wool pulled through a section of Pyrex tubing is cheap, strong,
and survivable (but not to alkali). Plastic foam is cheaper. Vycor
preforms are pricey. Engineer to use the stuff if you can. Don't do
the design first and then pursue availability of a miracle material.
We see this micromanagerial crap all the time in medical devices.
Biocompatiblity is only surface deep. The bulk material doesn't have
to be biocompatible, it simply has to omit any objectionable
breakthrough or blooming. Especially for acute exposure use once and
toss, you lay down an expensive micron over a really cheap inch that
meets all other specs. Surgical adhesions need *never* happen if
latex gloves are surface grafted with a micron of PVP. Who gives a
damn about the patient?
When I was in grad school - I remember a student who licked (or tried to
lick ) a small Vicor block - the O'l taste test for porosity.
- I suppose it wasn't funny - but I couldn't help laughing and cringing at
the same time. A person makes a unique sound when they try to scream and
pull a block off their tongue at the same time- she must have lost a few
taste buds and there was a little blood, but no serious injury.
As far as cheap and porous - you should be able to buy bisque fired rods -
not much porosity control, but it will be cheap.
If anyone is interested in specialty porous parts with specific chemical
resistance, controlled pore size and surface tension - I can give some
contacts.
lick ) a small Vicor block - the O'l taste test for porosity.
- I suppose it wasn't funny - but I couldn't help laughing and cringing at
the same time. A person makes a unique sound when they try to scream and
pull a block off their tongue at the same time- she must have lost a few
taste buds and there was a little blood, but no serious injury.
As far as cheap and porous - you should be able to buy bisque fired rods -
not much porosity control, but it will be cheap.
If anyone is interested in specialty porous parts with specific chemical
resistance, controlled pore size and surface tension - I can give some
contacts.
It's sort of off topic, but I was amused to read (in an older edition
of _Tile_Engineering_) of the story of how cinder blocks were
invented (called "structural tile" in the business).
A New York architect was visiting his brick supplier
out in the Midwest. At the time, the invention of steel-framed
buildings stimulated a boom in the construction of ever-higher
buildings, and this architect was well aware of the technical
problems facing the industry, in particular the need for
cheap, lightweight, fireproof building materials.
He was in the office of his brick supplier when he noticed
the odd way this guy prepared coffee. He had some sort
of porous block which he soaked in fuel, then set aflame
to provide the heat for the coffeepot. The architect asked
the brick guy what that block was, and he explained it was
an experimental brick he had made. He mixed the usual
brick clay in equal parts with sawdust and fired it, and after
the sawdust burned out he got this porous brick that
weighed about half what a normal brick weighs but was
almost as strong.
The architect immediately realized the importance of this
invention, and the structural tile industry was born.
of _Tile_Engineering_) of the story of how cinder blocks were
invented (called "structural tile" in the business).
A New York architect was visiting his brick supplier
out in the Midwest. At the time, the invention of steel-framed
buildings stimulated a boom in the construction of ever-higher
buildings, and this architect was well aware of the technical
problems facing the industry, in particular the need for
cheap, lightweight, fireproof building materials.
He was in the office of his brick supplier when he noticed
the odd way this guy prepared coffee. He had some sort
of porous block which he soaked in fuel, then set aflame
to provide the heat for the coffeepot. The architect asked
the brick guy what that block was, and he explained it was
an experimental brick he had made. He mixed the usual
brick clay in equal parts with sawdust and fired it, and after
the sawdust burned out he got this porous brick that
weighed about half what a normal brick weighs but was
almost as strong.
The architect immediately realized the importance of this
invention, and the structural tile industry was born.
QUOTE (Uncle Al+Apr 17 2004, 03:59 PM)
You can buy porous
ceramic or Vycor pre-form rods, ditto sintered metal rods.
Macroreticular carbon might come small enough. Possibly open-cell
polyimide foam.
Depends on what it has to survive. Can you use square rods? Cut
sheet,
Also note wicks used in heat pipes. Not necessarily rigid,
but can be made so. A fine mesh woven screen is often
used.
ceramic or Vycor pre-form rods, ditto sintered metal rods.
Macroreticular carbon might come small enough. Possibly open-cell
polyimide foam.
Depends on what it has to survive. Can you use square rods? Cut
sheet,
Also note wicks used in heat pipes. Not necessarily rigid,
but can be made so. A fine mesh woven screen is often
used.
Uncle Al,
Thanks everyone for your help. We were going to take rods and
machine them to taper them into points. Then, we were going to stick
them into a houseplant and place it in a pot of water, so that the
soil is moistened by the water.
I'm part of a group building a plant waterer for a product design
class.
So, borosilica isn't actually a wicking material, eh? More like
pyrex, then. Hmmph. Good to know. we shan't use wool pulled through a
tube, as we need wetness along the length of the rod.
So,
(1) as cheap as possible.
(2) as durable as, say, a soft pine.
(3) The material itself should wick.
(4) it should either be a 1/2 inch in diameter or be able to fit
through that hole. We can machine stuff down.
(5) About 5 inches long
(6) It'll need to tranfer up to a pint of water a week. If it's
faster, that's fine, as it'll equilibrate.
(7) The point being, it doesn't need to be fast or precise. It has to
be cheap and durable.
So, yeah, the internet's full of stuff. But, I can't really
navigate it, which is why I turn to you. Any help you could give me
would be great. I'm looking through these links for capillating rod,
but I don't even know if that's a gerund
ion
Thanks everyone for your help. We were going to take rods and
machine them to taper them into points. Then, we were going to stick
them into a houseplant and place it in a pot of water, so that the
soil is moistened by the water.
I'm part of a group building a plant waterer for a product design
class.
So, borosilica isn't actually a wicking material, eh? More like
pyrex, then. Hmmph. Good to know. we shan't use wool pulled through a
tube, as we need wetness along the length of the rod.
So,
(1) as cheap as possible.
(2) as durable as, say, a soft pine.
(3) The material itself should wick.
(4) it should either be a 1/2 inch in diameter or be able to fit
through that hole. We can machine stuff down.
(5) About 5 inches long
(6) It'll need to tranfer up to a pint of water a week. If it's
faster, that's fine, as it'll equilibrate.
(7) The point being, it doesn't need to be fast or precise. It has to
be cheap and durable.
So, yeah, the internet's full of stuff. But, I can't really
navigate it, which is why I turn to you. Any help you could give me
would be great. I'm looking through these links for capillating rod,
but I don't even know if that's a gerund
ion
You will be done in by bio-goo.
Might as well use a lightly fired porous brick. Other posts a have
noted how clay plus a powdered burnout fashoned into greenware give
you high porosity fired ware. Extruding terra cotta is very cheap.
Might as well use a lightly fired porous brick. Other posts a have
noted how clay plus a powdered burnout fashoned into greenware give
you high porosity fired ware. Extruding terra cotta is very cheap.
Uncle Al,
Won't the rods be cleanable? Or, will the particles work themselves
into teh pores ... problem. So, you'd recommend workign some fine
sawdust into terra cotta and firing it.
It sounds like a fair amount of testing to get something that
doesn't crumble but still wicks. Is there a producer of something like
this? Will someone extrude terra cotta cheaply for me?
And, this Vycor mentioned in another post is just about at our
price point, if we can keep it away from people's tongues.
Won't the rods be cleanable? Or, will the particles work themselves
into teh pores ... problem. So, you'd recommend workign some fine
sawdust into terra cotta and firing it.
It sounds like a fair amount of testing to get something that
doesn't crumble but still wicks. Is there a producer of something like
this? Will someone extrude terra cotta cheaply for me?
And, this Vycor mentioned in another post is just about at our
price point, if we can keep it away from people's tongues.
Not cleanable, eventually disposable. Bio-goo (glycocalyx) is
forever.
Talk to folk who make porous tile and porous terra cotta. Don't
reinvent the wheel. Vycor has much too fine a pore structure and is
much too expensive. You need mud fired into tens of microns, not
chemncially leached fused silca at tens of angstroms.
Think "Mexico" and chia pets.
forever.
Talk to folk who make porous tile and porous terra cotta. Don't
reinvent the wheel. Vycor has much too fine a pore structure and is
much too expensive. You need mud fired into tens of microns, not
chemncially leached fused silca at tens of angstroms.
Think "Mexico" and chia pets.
QUOTE (Uncle Al+Apr 17 2004, 04:11 PM)
Vycor has much too fine a pore structure and is
much too expensive. You need mud fired into tens of microns, not
chemncially leached fused silca at tens of angstroms.
Amazing the way people come into this forum,
ask for a material recommendation, then get advice
on space-grade or semiconductor-grade materials.
Then, we find out they're trying to repair a chair or
a crack in a wall or something.
much too expensive. You need mud fired into tens of microns, not
chemncially leached fused silca at tens of angstroms.
Amazing the way people come into this forum,
ask for a material recommendation, then get advice
on space-grade or semiconductor-grade materials.
Then, we find out they're trying to repair a chair or
a crack in a wall or something.
A wide pore size distribution is desirable for "wicking" - like a quilted
paper towel.
Large pores will transport the water rapidly and the smaller pores will
provide the capillary pressure for wicking
h = 2S/(rpg)
h = height
S = surface tension
r = radius of pore
p = density of water (or liquid)
g = gravitational constant
I used to design controlled pore ceramic filters and diffusers - getting an
extremely narrow pore size distribution was difficult at best.
- getting a wide pore size distribution on the other hand.....
I think porous brick or terra cotta will suit your needs just fine - at
30-40% porosity - the strength should be more than sufficient for your
application.
They sell similar devices used in hot boxes already - my late father-in-law
used (and purchased) planters with porous ceramic inserts to start his
plants.
I don't know where he got them..
paper towel.
Large pores will transport the water rapidly and the smaller pores will
provide the capillary pressure for wicking
h = 2S/(rpg)
h = height
S = surface tension
r = radius of pore
p = density of water (or liquid)
g = gravitational constant
I used to design controlled pore ceramic filters and diffusers - getting an
extremely narrow pore size distribution was difficult at best.
- getting a wide pore size distribution on the other hand.....
I think porous brick or terra cotta will suit your needs just fine - at
30-40% porosity - the strength should be more than sufficient for your
application.
They sell similar devices used in hot boxes already - my late father-in-law
used (and purchased) planters with porous ceramic inserts to start his
plants.
I don't know where he got them..
Gregg,
Thanks very much for your help. Paper towel worked great for our
proof of concept. The problem now, I guess, is baking these rods. It'd
be so nice if I could just find a vendor, which is one of the big
recommendations for Vycor. I know, kids Today...
Thanks, I needed an equation. Water has a surface tension of about
1 in cgs units, right? Oh, no. It's 72 dynes/cm(1). A dyne is an
g*cm/s^2, so it's 10^-5 Newtons, giving water an S of 0.072 N/m. So,
for a height of 5" (.30m/12") =0.125m, I'd need a pore size of
r = 2(0.072)m/(0.125*1000*10). Um, using 2*7.2 = 12.5 that's 0.0001m.
So, I need 'burnout' particles with a mean radius of a
tenth-millimeter or smaller, right? The smaller they are, the slower
the flow?
ion
(1) From http://hyperphysics.phy-astr.gsu.edu/hbase/surten.html,
courtesy of Google
Thanks very much for your help. Paper towel worked great for our
proof of concept. The problem now, I guess, is baking these rods. It'd
be so nice if I could just find a vendor, which is one of the big
recommendations for Vycor. I know, kids Today...
Thanks, I needed an equation. Water has a surface tension of about
1 in cgs units, right? Oh, no. It's 72 dynes/cm(1). A dyne is an
g*cm/s^2, so it's 10^-5 Newtons, giving water an S of 0.072 N/m. So,
for a height of 5" (.30m/12") =0.125m, I'd need a pore size of
r = 2(0.072)m/(0.125*1000*10). Um, using 2*7.2 = 12.5 that's 0.0001m.
So, I need 'burnout' particles with a mean radius of a
tenth-millimeter or smaller, right? The smaller they are, the slower
the flow?
ion
(1) From http://hyperphysics.phy-astr.gsu.edu/hbase/surten.html,
courtesy of Google
A 100 micron pore size and smaller is no problem for a porous ceramic (I
didn't check your calculations, but they look OK)
How much fluid flow are you looking for? - If your watering plants - I
wouldn't worry too much about the flow rate unless you live in a desert.
As far as finding a vendor - how many pieces are you looking for?
If it's 10's of thousands+ you can start with www.ceramics.com - try the
art shops and brick makers for starters. You'll increase your costs by an
order of magnitude if you go the technical ceramic route. Finding a vendor
will take a bit of leg work.
If you need only a few pieces - try a local potter (ask for bisque fired
pieces) or a local brick maker.
If you need to go the technical ceramics route try:
Coorstec - yes, the same people who make the beer.
Refractron
Seneca Ceramics - If they aren't too busy - the owner is a great guy and
technically very sharp (if your looking to start a business - he's the guy
to talk too)
didn't check your calculations, but they look OK)
How much fluid flow are you looking for? - If your watering plants - I
wouldn't worry too much about the flow rate unless you live in a desert.
As far as finding a vendor - how many pieces are you looking for?
If it's 10's of thousands+ you can start with www.ceramics.com - try the
art shops and brick makers for starters. You'll increase your costs by an
order of magnitude if you go the technical ceramic route. Finding a vendor
will take a bit of leg work.
If you need only a few pieces - try a local potter (ask for bisque fired
pieces) or a local brick maker.
If you need to go the technical ceramics route try:
Coorstec - yes, the same people who make the beer.
Refractron
Seneca Ceramics - If they aren't too busy - the owner is a great guy and
technically very sharp (if your looking to start a business - he's the guy
to talk too)
Gregg,
Thanks. I guess I'd just need to know what to use as a burnout material
(wood? Newsprint? Wax?,) how to get it to the right size, and how much
to use. Unless potters would tend to know that sort of thing.
I'm looking for flows of up to a pint a week.
We're building an alpha prototype, but if it flies we may need
thousands of them. Tens of thousands! Twelve for every home in america!
A potted plant on every window sill, and H2Ouseplanters on every potted
plant!
Thanks for the link. I've posted at ceramics.com:
http://www.ceramics.com/forum/msgs/15164.html
Thanks. I guess I'd just need to know what to use as a burnout material
(wood? Newsprint? Wax?,) how to get it to the right size, and how much
to use. Unless potters would tend to know that sort of thing.
I'm looking for flows of up to a pint a week.
We're building an alpha prototype, but if it flies we may need
thousands of them. Tens of thousands! Twelve for every home in america!
A potted plant on every window sill, and H2Ouseplanters on every potted
plant!
Thanks for the link. I've posted at ceramics.com:
http://www.ceramics.com/forum/msgs/15164.html
QUOTE (Ion Chalmers Freeman+Apr 17 2004, 04:08 PM)
Uncle Al,
Thanks everyone for your help. We were going to take rods and
machine them to taper them into points. Then, we were going to stick
them into a houseplant and place it in a pot of water, so that the
soil is moistened by the water.
I'm part of a group building a plant waterer for a product design
class.
So, borosilica isn't actually a wicking material, eh? More like
pyrex, then. Hmmph. Good to know. we shan't use wool pulled through a
tube, as we need wetness along the length of the rod.
So,
(1) as cheap as possible.
(2) as durable as, say, a soft pine.
(3) The material itself should wick.
(4) it should either be a 1/2 inch in diameter or be able to fit
through that hole. We can machine stuff down.
(5) About 5 inches long
(6) It'll need to tranfer up to a pint of water a week. If it's
faster, that's fine, as it'll equilibrate.
(7) The point being, it doesn't need to be fast or precise. It has to
be cheap and durable.
So, yeah, the internet's full of stuff. But, I can't really
navigate it, which is why I turn to you. Any help you could give me
would be great. I'm looking through these links for capillating rod,
but I don't even know if that's a gerund
ion
Kitchen paper towels (Extra Thirsty) rolled up and tucked into
plastic tubing. You need something on the outside to prevent
evaporation anyway.
Thanks everyone for your help. We were going to take rods and
machine them to taper them into points. Then, we were going to stick
them into a houseplant and place it in a pot of water, so that the
soil is moistened by the water.
I'm part of a group building a plant waterer for a product design
class.
So, borosilica isn't actually a wicking material, eh? More like
pyrex, then. Hmmph. Good to know. we shan't use wool pulled through a
tube, as we need wetness along the length of the rod.
So,
(1) as cheap as possible.
(2) as durable as, say, a soft pine.
(3) The material itself should wick.
(4) it should either be a 1/2 inch in diameter or be able to fit
through that hole. We can machine stuff down.
(5) About 5 inches long
(6) It'll need to tranfer up to a pint of water a week. If it's
faster, that's fine, as it'll equilibrate.
(7) The point being, it doesn't need to be fast or precise. It has to
be cheap and durable.
So, yeah, the internet's full of stuff. But, I can't really
navigate it, which is why I turn to you. Any help you could give me
would be great. I'm looking through these links for capillating rod,
but I don't even know if that's a gerund
ion
Kitchen paper towels (Extra Thirsty) rolled up and tucked into
plastic tubing. You need something on the outside to prevent
evaporation anyway.
A guy I worked for used porous ceramic tubes to water his entire garden!
- the tubes were scrap from work - The garden bed was raised and water
toughs (in pits below the garden bed) were used as a water supply. Porous
tubes wicked the water into the soil.
The tubes drained excess water during heavy rains and kept the soil moist
during dry spells - he just kept the water troughs full.
He has great yields!
- the tubes were scrap from work - The garden bed was raised and water
toughs (in pits below the garden bed) were used as a water supply. Porous
tubes wicked the water into the soil.
The tubes drained excess water during heavy rains and kept the soil moist
during dry spells - he just kept the water troughs full.
He has great yields!
QUOTE (Gregg+Apr 17 2004, 04:01 PM)
When I was in grad school - I remember a student who licked (or tried to
lick ) a small Vicor block - the O'l taste test for porosity.
- I suppose it wasn't funny - but I couldn't help laughing and cringing at
the same time. A person makes a unique sound when they try to scream and
pull a block off their tongue at the same time- she must have lost a few
taste buds and there was a little blood, but no serious injury.
As far as cheap and porous - you should be able to buy bisque fired rods -
not much porosity control, but it will be cheap.
If anyone is interested in specialty porous parts with specific chemical
resistance, controlled pore size and surface tension - I can give some
contacts.
I am a grad school research assistant. Iwould like to have those contacts for speciality porous parts with good wicking characteristics. Thanks. You may e-mail me on mukta_msl@yahoo.com
lick ) a small Vicor block - the O'l taste test for porosity.
- I suppose it wasn't funny - but I couldn't help laughing and cringing at
the same time. A person makes a unique sound when they try to scream and
pull a block off their tongue at the same time- she must have lost a few
taste buds and there was a little blood, but no serious injury.
As far as cheap and porous - you should be able to buy bisque fired rods -
not much porosity control, but it will be cheap.
If anyone is interested in specialty porous parts with specific chemical
resistance, controlled pore size and surface tension - I can give some
contacts.
I am a grad school research assistant. Iwould like to have those contacts for speciality porous parts with good wicking characteristics. Thanks. You may e-mail me on mukta_msl@yahoo.com
My mother used string as a wick (same application).
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