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'[OT] Water pump ideas'
2006\03\01@000840 by Robert Ammerman

picon face
The Homebrew fountain thread  reminded me of a project I have on the back
burner....


I am considering building a cold water reservoir to connect to the filtered
water dispenser I have installed on my kitchen sink. What I would like to do
is place a hyper-insulated water container between the filter and the
faucet. This container would have two ports and an internal baffle system to
mix up the water when water is flowing.

One of the ports would connect to both the incoming water line and the
output of a small pump.

The other port would connect to the faucet and the input of the pump.

In the pump loop would be a water block, much like that used for water
cooled computer systems, which would be cooled by a peltier device, the hot
side of which would by sinked by a heatsink and fan.

And of course it will all be controlled by a PIC :-)

All of the pieces have come together very nicely except one. I am having
trouble finding a water pump that:

1: Can move moderate volumes,

2: At very low head,

3: Quietly,

4: Cheaply,

5: and is safe for potable water (drinking water if any non-English speakers
don't know the word)

--------------------------

An alternative idea I had was not using a pump at all, but rather thermally
connecting the reservoir directly to the peltier. I see two issues:

1: Much more difficult to effectively hyperinsulate the reservoir (I
considered moving baffles that would cover the whole pelter/sink/fan
assembly with insulation when not active)

2: A problem keeping the water well mixed to spread the cool.

Primary goals:

1: Reasonable implementation cost

2: Low operating cost

3: Quiet

4: Modest short term demand capability. Say 2 L immediately at ambient - 15
degrees C or so, a two or three hour recovery time is fine.

5: Fun doing it :-)

Any good alternatives or ideas?

Bob Ammerman

2006\03\01@015824 by Russell McMahon

face
flavicon
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> All of the pieces have come together very nicely except one. I am
> having
> trouble finding a water pump that:
>
> 1: Can move moderate volumes,
>
> 2: At very low head,
>
> 3: Quietly,
>
> 4: Cheaply,
>
> 5: and is safe for potable water (drinking water if any non-English
> speakers
> don't know the word)

1. Any number of small fountain pumps fill the bill (and the Peltier
chamber ;-) ).
Most use magnetically coupled rotors with all surfaces in plastic.
Potentially highly suitable for drinking water. Specific
implementations may make a given unit not so so check carefully.

2.    Peristaltic pump.

3. You could try "my" 'Pistonless Piston Pump. I invented this as a
rocket propellant pump some years ago and only subsequently found out
that Lockheed Martin had patented the idea about 4 years before that.
A version of this was independently invented by and being developed in
secret by Flometrics (see it at
http://www.flometrics.com/rockets/rocket_pump/rocketpump.htm) when I
caused them some consternation by publishing my design. They now have
numerous patents on various aspects. An idea which I have public
domained and which is *NOT* covered by the LM patent is to use a
single chamber pump. The LM patent is based on 3 or more chambers with
2 being mentioned as a throw away at the very end. 2 chambers is fine.
If you wish, you can use 2 or more of public domain single chamber
pumps with a common controller running them in appropriate phase
relationship, when they look suspiciously like the patented version.
It so happens that one of the very first British patents (1750s?) was
for a mine pump that worked on the same principle - there is little
new under the sun.

BUT - at the basic level, it goes like this.
Seal chamber.
Blow in air.
Water is expelled to Peltier cell.
Turn off air.
Open valve to chamber.
Let water drain back in from Peltier cell.
Not exactly a stunning concept - but some day rockets will go to orbit
on that principle. It has advantages over all current methods (and
disadvantages).


A non return valve or 2 is needed - see Flometrics site to see how
it's done.
Water is touched only by air.
If air supply is potable quality them water is too.


       RM

2006\03\01@061041 by Howard Winter

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Russell,

On Wed, 01 Mar 2006 19:58:27 +1300, Russell McMahon wrote:

> 3. You could try "my" 'Pistonless Piston Pump. I invented this as a
> rocket propellant pump some years ago and only subsequently found out
> that Lockheed Martin had patented the idea about 4 years before that.
> A version of this was independently invented by and being developed in
> secret by Flometrics (see it at
> http://www.flometrics.com/rockets/rocket_pump/rocketpump.htm) when I
> caused them some consternation by publishing my design.

I can't quite see why it's that complicated - why not just meter the Very High Pressure into the top of the
main tank and force it out that way?  What does the oscillating flow achieve, apart from a pulsed output?

{Quote hidden}

Are you referring to Thomas Savery's pump?  In which case it was 1698!  :-)

Cheers,


Howard Winter
St.Albans, England


2006\03\01@075902 by olin piclist

face picon face
Robert Ammerman wrote:
> 1: Can move moderate volumes,
> 2: At very low head,
> 3: Quietly,
> 4: Cheaply,

Sounds like a fish tank pump.  I've never kept fish, but I did use a fish
tank pump once to agitate a temperature controlled water bath.  It worked
fine.  I think it meets all your criteria.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\03\01@090515 by Robert Ammerman

picon face
Potable water???

----- Original Message -----
From: "Olin Lathrop" <spam_OUTolin_piclistTakeThisOuTspamembedinc.com>
To: "Microcontroller discussion list - Public." <.....piclistKILLspamspam@spam@mit.edu>
Sent: Wednesday, March 01, 2006 8:00 AM
Subject: Re: [OT] Water pump ideas


{Quote hidden}

> --

2006\03\01@095329 by Mike Hord

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On 3/1/06, Robert Ammerman <rammermanspamKILLspamverizon.net> wrote:
> Potable water???

ABSOLUTELY.  Remember, you're only drinking the water- fish
have to BREATHE it.

I have a couple of friends who are big into saltwater aquaria.  The
efforts they go through to ensure that the water going into their
fishtank is pure is pretty amazing.  I have NO doubt that any
pump designed for fishtank operation meets or exceeds the
cleanliness standards for human potable pumps, so long as it is
from a reputable dealer and manufacturer.  I would stake my
health on it

Mike H.

> > Robert Ammerman wrote:
> >> 1: Can move moderate volumes,
> >> 2: At very low head,
> >> 3: Quietly,
> >> 4: Cheaply,
> >
> > Sounds like a fish tank pump.  I've never kept fish, but I did use a fish
> > tank pump once to agitate a temperature controlled water bath.  It worked
> > fine.  I think it meets all your criteria.

2006\03\01@110527 by Robert Ammerman

picon face
Ah....

I left out one pump criterion:

Static pressure of liquid being pumped is 40-80psi above atmosphere (ie: the
reservoir is under city water pressure). Note that the pump is recirculating
through the reservoir, so it only sees a small head.

Bob Ammerman


2006\03\01@111738 by Michael Rigby-Jones

picon face


{Quote hidden}

Buy a filter jug, fill with tap water and place inside refrigerator.  Fulfils requirements 1 through 4 ;-)

Regards

Mike

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2006\03\01@123607 by olin piclist

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Robert Ammerman wrote:
>> Sounds like a fish tank pump.  I've never kept fish, but I did use a
>> fish tank pump once to agitate a temperature controlled water bath.
>> It worked fine.  I think it meets all your criteria.
>
> Potable water???

I'm not sure what you're asking.  Are you worried about whether water that
has been thru a fish tank pump is safe to drink?  I don't see why not.  Most
of them are built such that the water only touches plastic, although this is
something that would need to be checked.  Obviously they are designed to not
harm fish that have to live in the water.  I don't think humans are less
tolerant of what they drink.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\03\01@143851 by Peter

picon face

> from a reputable dealer and manufacturer.  I would stake my
> health on it

Don't. Fish and people are very different and there are a number of
substances that can kill one while not harming the other. F.ex. alcohool
kills fish even at low concentrations but is relatively harmless to
humans even at 40 proof. This is followed by a very long list of
substances you likely would not like to drink but fish thrive on (or
in). Starting with salt water, for example.

Peter

2006\03\01@151020 by Michael Rigby-Jones

picon face


>-----Original Message-----
>From: piclist-bouncesspamspam_OUTmit.edu [@spam@piclist-bouncesKILLspamspammit.edu]
>Sent: 01 March 2006 19:39
>To: Microcontroller discussion list - Public.
>Subject: Re: [OT] Water pump ideas
>
>
>
>> from a reputable dealer and manufacturer.  I would stake my
>health on
>> it
>
>Don't. Fish and people are very different and there are a number of
>substances that can kill one while not harming the other.
>F.ex. alcohool
>kills fish even at low concentrations but is relatively harmless to
>humans even at 40 proof. This is followed by a very long list of
>substances you likely would not like to drink but fish thrive on (or
>in). Starting with salt water, for example.

Relatievly few people keep salt water fish, too hard to look after.  Fresh water fish don't like the salt too much..

Mike

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information contained in it may be confidential and/or protected by
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not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
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No part of this message can be considered a request for goods or
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2006\03\01@152631 by David VanHorn

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You never hear much of brackish water fish.

2006\03\01@153627 by Dwayne Reid

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At 09:17 AM 3/1/2006, Michael Rigby-Jones wrote:

> >Any good alternatives or ideas?
>
>Buy a filter jug, fill with tap water and place inside
>refrigerator.  Fulfils requirements 1 through 4 ;-)

Better yet - eliminate the Peltier unit completely - just run the
hose into and out of the fridge.  Or combine both ideas above: run
hose from filter unit to reservoir inside fridge.

I know . . . I know.  Doesn't meet the original spec.  Just a thought.

dwayne

--
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Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
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2006\03\01@155128 by Mike Hord

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On 3/1/06, David VanHorn <RemoveMEdvanhornTakeThisOuTspammicrobrix.com> wrote:
> You never hear much of brackish water fish.

Actually, mollies and some types of puffers do quite well as
brackish water fish, to the point where they can be acclimated
into either fresh(ish) or salt(ish) tanks.

Mike H.

2006\03\01@161918 by Dave Tweed

face
flavicon
face
From: spamBeGoneolin_piclistspamBeGonespamembedinc.com (Olin Lathrop)
> Robert Ammerman wrote:
> > > Sounds like a fish tank pump. I've never kept fish, but I did use a
> > > fish tank pump once to agitate a temperature controlled water bath.
> > > It worked fine. I think it meets all your criteria.
> >
> > Potable water???
>
> I'm not sure what you're asking. Are you worried about whether water
> that has been thru a fish tank pump is safe to drink? I don't see why
> not. Most of them are built such that the water only touches plastic,
> although this is something that would need to be checked. Obviously they
> are designed to not harm fish that have to live in the water. I don't
> think humans are less tolerant of what they drink.

Most fish tank pumps pump air, not water.

-- Dave Tweed

2006\03\01@164030 by olin piclist

face picon face
Dave Tweed wrote:
> Most fish tank pumps pump air, not water.

But water pumps are out there.  I know because I bought the pump for my
temperature controlled water bath at a pet shop and it was sold as a "fish
tank pump".  Of course that was in 1980, so maybe the fish have developed
better technology by now.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\03\01@172453 by David VanHorn

picon face
On 3/1/06, Olin Lathrop <TakeThisOuTolin_piclistEraseMEspamspam_OUTembedinc.com> wrote:
>
> Dave Tweed wrote:
> > Most fish tank pumps pump air, not water.


Where'd you get that idea?

Powerheads are very common, for undergravel filters (which were first done
with bubbling air), and then there's the back of tank pumps which also do
water only.

The back of tank units have the electrical part isolated from the water, and
the powerhead units are usually completely submersible.

The vibrating bellows pumps are still around, but not a serious player.

2006\03\01@172727 by Peiserma

flavicon
face
piclist-bounces@mit.edu wrote:
> Dave Tweed wrote:
>> Most fish tank pumps pump air, not water.
>
> But water pumps are out there.  I know because I bought the
> pump for my temperature controlled water bath at a pet shop
> and it was sold as a "fish tank pump".  Of course that was in
> 1980, so maybe the fish have developed better technology by now.

and of course their own terminology. Often called powerheads.

I used to use a brand called RIO for my reef tank. I recall them
being less expensive than other brands, and a marine environmnent
is pretty harsh, so they had to be replaced often. It's amazing
how fast the powerheads get completely encrusted by corraline...

2006\03\01@173338 by Peter

picon face

On Wed, 1 Mar 2006, Russell McMahon wrote:

> 3. You could try "my" 'Pistonless Piston Pump. I invented this as a
> rocket propellant pump some years ago and only subsequently found out
> that Lockheed Martin had patented the idea about 4 years before that.
> A version of this was independently invented by and being developed in
> secret by Flometrics (see it at
> http://www.flometrics.com/rockets/rocket_pump/rocketpump.htm) when I
> caused them some consternation by publishing my design. They now have
> numerous patents on various aspects. An idea which I have public
> domained and which is *NOT* covered by the LM patent is to use a
> single chamber pump. The LM patent is based on 3 or more chambers with
> 2 being mentioned as a throw away at the very end. 2 chambers is fine.
> If you wish, you can use 2 or more of public domain single chamber
> pumps with a common controller running them in appropriate phase
> relationship, when they look suspiciously like the patented version.
> It so happens that one of the very first British patents (1750s?) was
> for a mine pump that worked on the same principle - there is little
> new under the sun.

Why is this good ? Here is the Savery engine:

http://www.egr.msu.edu/~lira/supp/steam/savery.htm

With any high speed pump the speed will be limited mostly by the low
pressure ducting and suction therein, I think. A rocket certainly needs
high speed liquid pumping (besides the pressure). And why is such a
design 'lighter' than a turbopump ? A 20hp turbo (automotive, built of
common materials and not aerospace stuff) is smaller than a six-pack of
beer and weighs under 4 kgs. How can a gas piston pump compete with it ?

Afaik gas pressurized fuel feed for rockets was abandoned since the
1950's. No ?

Peter

2006\03\01@234935 by William Chops Westfield

face picon face

On Mar 1, 2006, at 11:38 AM, Peter wrote:

> alcohool kills fish even at low concentrations but is relatively
> harmless to humans even at 40 proof.

Even at similar ratios of alcohol per body mass?

BillW

2006\03\01@235256 by Robert Ammerman

picon face

----- Original Message -----
From: "Robert Ammerman" <RemoveMErammermanspamTakeThisOuTverizon.net>
To: "Microcontroller discussion list - Public." <piclistEraseMEspam.....mit.edu>
Sent: Wednesday, March 01, 2006 11:05 AM
Subject: Re: [OT] Water pump ideas


{Quote hidden}

To answer my own post: given a submersible pump, I could always place the
whole pump inside the pressurized system. Then I'd only have to bring the
power leads out thru an appropriate pressure-resisting interface.

Bob Ammerman

2006\03\02@000330 by William Chops Westfield

face picon face

On Mar 1, 2006, at 2:33 PM, Peter wrote:

> And why is such a design 'lighter' than a turbopump ? A 20hp
> turbo (automotive, built of  common materials and not aerospace
>  stuff) is smaller than a six-pack of beer and weighs under 4 kgs.

> Afaik gas pressurized fuel feed for rockets was abandoned
> since the 1950's. No ?
>
Certainly not in the amateur rocketry space, where 4kg is quite
heavy...

BillW

2006\03\02@000528 by Sergey Dryga

face picon face
William "Chops" Westfield <westfw <at> mac.com> writes:

>
>
> On Mar 1, 2006, at 11:38 AM, Peter wrote:
>
> > alcohool kills fish even at low concentrations but is relatively
> > harmless to humans even at 40 proof.
>
> Even at similar ratios of alcohol per body mass?
>
> BillW
I would venture a guess that it depends on the kind of fish and a person.  I
vaguely remember reading a medical encyclopedia which mentioned that lethal
dose of ehtyl alcohol is 450mL for an average person, except russians.
(BTW, I am russian, so it's OK to make this joke.)

Seriously, pumps not specified for use with potable water may leak something
into the water, which might be present in low enough concentration to not be
acutely poisonus, but have long-term effects.  Fish usually do not live as long
as humans do and do not have as much medical attention.

Sergey Dryga

2006\03\02@035619 by Alan B. Pearce

face picon face
> Afaik gas pressurized fuel feed for rockets was abandoned
> since the 1950's. No ?

What do you mean by pressurized fuel feed? The Ariane 5 rocket uses helium
to pressurise the oxygen and hydrogen tanks during flight, to maintain the
feed pressure out of the tank as the fuel is used AIUI.

2006\03\02@051731 by Russell McMahon

face
flavicon
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>> 3. You could try "my" 'Pistonless Piston Pump. I invented this as a
>> rocket propellant pump some years ago and only subsequently found
>> out
>> that Lockheed Martin had patented the idea about 4 years before
>> that.
>> A version of this was independently invented by and being developed
>> in
>> secret by Flometrics (see it at
>> http://www.flometrics.com/rockets/rocket_pump/rocketpump.htm) when
>> I
>> caused them some consternation by publishing my design.

> I can't quite see why it's that complicated - why not just meter the
> Very High Pressure into the top of the
> main tank and force it out that way?  What does the oscillating flow
> achieve, apart from a pulsed output?

To answer several people's questions including the above.

1.    Pressure fed rockets are still very much in use. In fact there
is a very good case for using pump fed systems only for first stages
and not necessarily even then. Google "Robert Truax" [[ the great,
admiral etc :-) ]] - a very very clued up gent from the golden age of
US rocketry (50s-60s) and still going. FWIW he designed Evil Knevel's
Snake River canyon steam rocket and many of the rocket powered drag
cars of the 60's and 70s.

2.    THE hardest thing to design in a turbo-pump fed rocket system is
the turbo-pump. They are works of immensely arcane black magic. A
rocket system is really almost just a support system for its turbopump
:-). And this applies to the Spec Shuttle as well. Next comes the eg
topping cycle engines that the TPs feed. Eliminating the TP if
possible is a grweat gain.

3.    As is explained on the Flometrics site, for a range of rocket
configurations and sizes (not all) the PPP (Pistonless Piston Pump)(my
name - they just say pistionless pump) is superior in performance and
mass and more to a TP system. ALL aspects of the system must be
considered.

4.    Pressurising the main tank works fine EXCEPT that to attain the
required pressures the tank must be far far far too heavy due to the
need to resist the pressures involved. Most main tabnks are
pressurised to a few psi and the TP takes it from there. Also, in a
fully pressurised tank system at very high pressures the mass of
pressurant gas is amazingly high. Google on "tridyne" to see one way
of attempting to address this issue - the pressurant gas is 'burnt" to
increases its temperature and pressure. It works BUT stand clear,
don't try this at home, YMMV, boo.....

If you pressurise your main tabnk to say 2000m psi not only is it
heavy BUT all the gas is there at the end of the burn and your final
mass may be more than doubles. As mass ratio (Mfull/Mempty is an ultra
critical parameter in orbital ocketry this is very bad. Only lowish
pressure systems can afford to do it this way. The PPP has all the
advantages of the pressurised tank system and few of the
disadvantages.

What the PPP does is allow you to have a very small tank which is
pressurised to full pressure and then emptied. It is then refilled
from the main tabnk at low pressure while one or more companions are
emptied at high pressure. A great bonus is that after each emptying of
the pump chamber the pressurant gas can be thrown away and does not
have to be taken along for the whole ride. This is an immnse advantage
over pressurised tank rockets.

Compared to the TP the PPP is lighter in many (not all) cases when all
system masses are considered. It is also *MUCH* easier to build.
Almost anyone who wanted to could build a reasonable PPP with low tech
tooling. A decent TP requires myultiple advanced degrees in the black
arts and typically millions of dollars. Or 100's of millions for the
very best.

> Are you referring to Thomas Savery's pump?  In which case it was
> 1698!  :-)

That's the one.
The pressure stroke, which they don't dwell on greatly there, is
essentially a PPP at work.
My ideas are different enough to be different but based on the same
broad principles.
I didn't know about Savery's pump when I thought of the PPP. I was
AFAIR looking at a Lawrence Livermore labs rocket piston pump when it
occurred to me that the pistons were an unnecessary appendage :-).

The PPP is so trivially obvious that once people understand it it
feels that they have known about the principle forever :-).

It's only when you go into it in detail that it becomes obvious just
how good it can be compared to existing alternatives.

____________________

> Why is this good ? Here is the Savery engine:
>
> http://www.egr.msu.edu/~lira/supp/steam/savery.htm

> With any high speed pump the speed will be limited mostly by the low
> pressure ducting and suction therein, I think. A rocket certainly
> needs
> high speed liquid pumping (besides the pressure).

Filling is not the major issue. You only need to be able to fill a
chamber in the same time it takes to empty it. This is an easy task in
most cases. A much lower power filling pump could be used but in
rockets modest tank pressurisation or even justv the "head" induced by
acceleration are enough to do the job. For simple low pressure plastic
versions gravity feed alone can suffice.

The output pressure can be designed to be whatever is required, quite
independent of the low pressure aspects.

> And why is such a
> design 'lighter' than a turbopump ? A 20hp turbo (automotive, built
> of
> common materials and not aerospace stuff) is smaller than a six-pack
> of
> beer and weighs under 4 kgs. How can a gas piston pump compete with
> it ?

Flometrics provide some worked examples I believe.
The relevant mass is the total system mass BUT a PPP itself is a
relatively trivial device - 2 (typically) pump chambers plus some non
return valves plus one multiport controlled valve per pump chamber. I
suspect that in the example you give a PPP could be of much the same
size and mass. The big difference in the automotive example is that
the gas feed to the turbine in the automotive example would not be
suitable for driving a PPP of arbitraily great pressure output but it
is capable of driving a turbine which dricves a "pump" of whatever
characteristics are reqyuired so in that application a turbo has
advantages. In rocketry the characteristics of the energy (drive gas)
source can be tailored to the application.

> Afaik gas pressurized fuel feed for rockets was abandoned since the
> 1950's. No ?

No. See above. Still very much in use and even more potentially
applicable than currently employed. One problem with orbital rocketry
is that the big budgets have locked in certain very expensive
assumptions and design paradigms which are not necessarily the best
ones now and may never have been. There is vast debate on this in the
rocketry community but various up and coming systems use quite
different design approaches to those of the main stream past.


       RM



       RM

2006\03\02@051756 by Russell McMahon

face
flavicon
face
{Quote hidden}

James and others who are interested in alternative and reduced energy
lifestyles and related issues should have a look at the Flometrics
site. The PPP has various applications quite unrelated to rocketry.
With it you can build extremely simple pumps using gas pressure. While
other means will often be superior there are instances where this may
do the job better than alternatives. I haven't tried it but you could
build a plastic (or wood, probably :-)) air-powered down-hole PPP to
lift water over large heads. Just as Savery did.



       RM


2006\03\02@143509 by Peter

picon face

On Wed, 1 Mar 2006, William Chops Westfield wrote:

>> alcohool kills fish even at low concentrations but is relatively
>> harmless to humans even at 40 proof.
>
> Even at similar ratios of alcohol per body mass?

I don't know about that but I know that fish die very horribly when
f.ex. fruit mass from alcohool-distillation is dumped into a river.
There you would have maybe 10 tons of material with <3% alcohool in it
dumped into 10,000+ tons of moving water and the next day all the fish
downstream from there are belly-up.

Peter

2006\03\02@143952 by Peter

picon face

>> Static pressure of liquid being pumped is 40-80psi above atmosphere
>> (ie: the reservoir is under city water pressure). Note that the pump
>> is recirculating through the reservoir, so it only sees a small head.

Could you not set up a convection circuit between the chambers ? Perhaps
using a small auxiliary heater in the up-duct ?

Peter

2006\03\02@145215 by Peter

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On Thu, 2 Mar 2006, Alan B. Pearce wrote:

>> Afaik gas pressurized fuel feed for rockets was abandoned
>> since the 1950's. No ?
>
> What do you mean by pressurized fuel feed? The Ariane 5 rocket uses helium
> to pressurise the oxygen and hydrogen tanks during flight, to maintain the
> feed pressure out of the tank as the fuel is used AIUI.

Pressurized to engine inlet pressure. Which is not the case afaik.
Everyone uses turbopumps for liquid fuel rockets. Even the WW2 V2 had
turbopumps. Only small rockets may use something else as someone pointed
out (and imho that would be a bad step because the heavy plumbing
required to sustain chamber pressure is even more penalizing
procentually when the fuel volume is small). But I only read about these
things.

Peter

2006\03\02@150438 by Peter

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On Thu, 2 Mar 2006, Russell McMahon wrote:

>> With any high speed pump the speed will be limited mostly by the low
>> pressure ducting and suction therein, I think. A rocket certainly needs
>> high speed liquid pumping (besides the pressure).
>
> Filling is not the major issue. You only need to be able to fill a chamber in
> the same time it takes to empty it. This is an easy task in most cases. A
> much lower power filling pump could be used but in rockets modest tank
> pressurisation or even justv the "head" induced by acceleration are enough to
> do the job. For simple low pressure plastic versions gravity feed alone can
> suffice.

Huh ? Filling a chamber through a metering orifice from a low head and
then emptying it through another metering orifice at much higher
pressure does not sound like an easy way to get 50% duty cycle. Imho
with pressure ratios above 1:10 getting this right may be even more
interesting than making a crude turbo pump. Of course any interruption
in fuel feed to the engine means flameout. No ?

Peter

2006\03\02@164639 by James Newtons Massmind

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> Any good alternatives or ideas?

It probably has nothing that would interest you, but I do have a page on
water pumps:
http://www.massmind.org/other/pump/water Mostly related to unusual pumping
methods.

---
James Newton, massmind.org Knowledge Archiver
EraseMEjamesspammassmind.org 1-619-652-0593 fax:1-208-279-8767
All the engineering secrets worth knowing:
http://techref.massmind.org What do YOU know?


2006\03\02@175141 by Jason

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From: "Peter" <RemoveMEplpEraseMEspamEraseMEactcom.co.il>
Sent: Wednesday, March 01, 2006 11:38 AM


> Don't. Fish and people are very different and there are a number of
> substances that can kill one while not harming the other. F.ex. alcohool
> kills fish even at low concentrations but is relatively harmless to
> humans even at 40 proof. This is followed by a very long list of
> substances you likely would not like to drink but fish thrive on (or
> in). Starting with salt water, for example.

Do you know where you heard that alcohol kills fish in small quantities?

On Mythbusters recently, they tested the myth that vodka makes a good bee
killer.  A couple of their control bees in water died, but all the vodka
bees survived.  I'm wondering if the fish story is similar.

Also, I can't think of anything in a pump made of refined and synthetic
materials that would be harmful to humans and not fish.

Overall you're probably right just based on the legal requirements to make
something suitable for humans.  They could use Pb solder in a fish pump but
not a human pump for example.


2006\03\02@183914 by Danny Sauer

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Jason wrote regarding 'Re: [OT] Water pump ideas' on Thu, Mar 02 at 16:53:
> Do you know where you heard that alcohol kills fish in small quantities?

I recently had to euthanize a fish.  The preferred method, apparently,
is to put the fish in water with a little bit of clove oil (a few
drops per cup of water, IIRC) to knock it out.  Clove oil, BTW, is
what vets use to anesthetize fish for operations - and is found in
some toothache remedies.  Anyway, after the fish is unconscious, you
dump in some vodka (like 25% by volume of water or more, again IIRC)
to kill it.  If you go overboard with the clove oil you can also
potentially kill it, but leaving the fish in the vodka solution will
kill it - for this fish it took probably just a few minutes before it
totally stopped breathing.  And this was the cheapest vodka I could
get - It probably would've knocked *me* out if I'd drank any of it. :)

Granted, 25% by volume is a rather high concentration, and I probably
went over that, but I wasn't really interested in seeing just how
little I could get away with, and the fish was pretty sick anyway (had
stopped eating several days prior, couldn't swim properly for weeks,
etc) so it wouldn't have been an ideal specimen to test on.

--Danny

2006\03\03@072711 by Russell McMahon

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>> The Ariane 5 rocket uses helium
>> to pressurise the oxygen and hydrogen tanks during flight, to
>> maintain the
>> feed pressure out of the tank as the fuel is used AIUI.

> Pressurized to engine inlet pressure. Which is not the case afaik.
> Everyone uses turbopumps for liquid fuel rockets.

For the first stage, largely true.
For upper stages, not nearly so true.
For in space applicationms, far less true again.
Plagarising for convenience: Two common pressure fed upper stage
engines
are the Aerojet AJ10-118K engine used on the Delta II, and the Space
Shuttle OMS engine.  The former has a chamber pressure of 8.84 atm.,
while the latter runs at 8.62 atm.

The Delta II is extremely time proven and the Shuttle OMS has a long
history but rather less flights.

> Even the WW2 V2 had
> turbopumps. Only small rockets may use something else as someone
> pointed
> out (and imho that would be a bad step because the heavy plumbing
> required to sustain chamber pressure is even more penalizing
> procentually when the fuel volume is small). But I only read about
> these
> things.

A pump fed design MAY make sense for a first stage due to atmospheric
pressure. For stages working in little or no atmosphere they make far
less sense. If your engine MUST go all the way from ground to orbit
(eg STS (aka Shuttle) main engines) then you will end up using a pump
fed system where it makes less sense to do so. Pump fed designs are
also liable to have higher efficiencies due to very high chamber
pressures and higher rsultant Isp's *BUT* efficiency is not
necessarily what should be being optimised in a launcher. The obvious
thing to optimise is often launched payload per unit cost and high
efficiency systems are almost always dearer than big dumb systems.
Forthcoming designs tend to be bigger (for a given payload) and dumber
rather than efficient.


       RM


2006\03\03@074219 by Russell McMahon

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>> Filling is not the major issue. You only need to be able to fill a
>> chamber in
>> the same time it takes to empty it.

> Huh ? Filling a chamber through a metering orifice from a low head

Filling via a "Metering orifice" doesn't really come into it.
Maybe it would be clearer to say "You only need to be able to fill a
chamber in less than the time that it takes to empty it".
Imagine a bucket being emptied by a high pressure garden pump. Filling
the bucket from a large adjacent tank faster than it is emptied is
largely a matter of having a large enough pipe and a suitable tap.
There may be engineering issues but the problems are minor compared to
dealing with the high pressure flow.

> ... then emptying it through another metering orifice at much higher
> pressure does not sound like an easy way to get 50% duty cycle.

Duty cycle does not have to be 50% - just not MORE than 50%. ie if the
pump chamber empties in 2 seconds and there are two pump chambers then
filling it in 1.8 seconds, or 1.5 or 1 is fine.

> ... with pressure ratios above 1:10 getting this right may be even
> more
> interesting than making a crude turbo pump.

1. No.
2. Crude turbo pumps are not what is being considered here. A properly
engineered PPP will out-perform the best possible turbo-pumps in
selected cases. And typical turbo pumps in more cases. And be worse
than typical turbo-pumps in others. It's a matter of addressing the
cases where it's the correct solution.

See the flometrics site for worked examples.

Note that Flometrics bread and butter is pump, including turbo-pump
design and optimisation and that the PPP is a peripheral project.

> Of course any interruption
> in fuel feed to the engine means flameout. No ?

Total interuption - yes.
Some flow instability is tolerable. See flometrics graphs.
A bigger demon (because it's easier to cause and hard to analyse) is
combustion instability. Rocket motors with CI can suffer spontaneous
dismantlement with ease. Flow separation in the nozzle can also be
"rough" and enough variation in propellant feed can assist this to
happen. Maintaining a suitable pressure across the injectors and
having a degree of throttling (even quite small) for control can help
muchly.

As long as your next pump chamber is filled and up to pressure
substantially before the working one is empty then "handover" should
be able to be as smooth as you are clever. Flometrics graphs of actual
performance show some pressure variation at handover BUT in theory a
suitably well engineered system should be able to make the transition
with little or no variation. I don't see that the 3 chamber LM design
is a great help here in theory but it may be in practice.

All too often the difference between theory and practice is greater in
practice than in theory :-).

Bottom line is that when the total system is examined the PPP may well
be the right solution compared to a turbo-pump system in some cases
and not in others.


       RM





2006\03\03@074219 by Russell McMahon

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>> Any good alternatives or ideas?

> It probably has nothing that would interest you, but I do have a
> page on
> water pumps:
> http://www.massmind.org/other/pump/water Mostly related to unusual
> pumping
> methods.

You haven't got a bubble pump :-).

Place vertical tube in water open at both ends.
Locate top of tube a designed height above water surface.
Locate bottom of tube a designed depth below water surface.

Bubble air into bottom of tube.
Design bubble size and air flow to suit various system dimensions.

Bubbles rise and expand.
Water is driven up the tube by the ascending bubbles.
Water (and air) exit from the top of the tube.

Design would be interesting.
Done with a clear tube in eg a fish tank would be fun.


       RM

2006\03\03@090415 by Howard Winter

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Russell,

On Sat, 04 Mar 2006 01:38:42 +1300, Russell McMahon wrote:

{Quote hidden}

Also called an "Airlift", it's used for clearing sand etc. from sub-aqua archaeological "digs" and wreck
investigations.  The lift pipe is about 100mm across, usually.  You have to position the top away from above
you, or it suddenly gets very difficult to see!  :-)

> Design would be interesting.
> Done with a clear tube in eg a fish tank would be fun.

We had one in a fish tank when I was a kid - lifted the water from the bottom and dropped it into a tank-side
filter bed, from where having passed through the filters it drained back into the tank.

Makes for an interesting question:  If you were floating in the water when a load of airbubbles were released
below, would you be bouyed-up by the rising air/water, or sink due to the lowering of displaced mass?

Cheers,


Howard Winter
St.Albans, England


2006\03\03@091357 by Howard Winter

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Russell,

On Sat, 04 Mar 2006 01:16:32 +1300, Russell McMahon wrote:

>...
> A pump fed design MAY make sense for a first stage due to atmospheric
> pressure. For stages working in little or no atmosphere they make far
> less sense. If your engine MUST go all the way from ground to orbit
> (eg STS (aka Shuttle) main engines) then you will end up using a pump
> fed system where it makes less sense to do so.

A thought has just occurred:  "Your" pressure fed pump needs gravity to keep the pressurised gas "above" the
liquid fuel so that only fuel exits the tank, so presumably it wouldn't work in zero-G?

And further, how does *any* liquid fuel system work in zero-G?  Is there some type of bladder or membrane with
pressure on the far side which keeps the fuel in contact with the exit-port?

Finally, it was reported a few years ago that after the breakup of the USSR they discovered a warehouse full
of rocket engines that were much more efficient than Western ones of similar size, because if I remember
rightly they used some sort of pre-heating of the fuel, which idea had been abandoned by the West because of
explosive accidents in development.  There was talk that since the Russians had solved the problem, this was
going to form the basis of future rocket engine designs.  Any idea if that is now happening?

Cheers,


Howard Winter
St.Albans, England


2006\03\03@093912 by Russell McMahon
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>> Any good alternatives or ideas?

> It probably has nothing that would interest you, but I do have a
> page on
> water pumps:
> http://www.massmind.org/other/pump/water Mostly related to unusual
> pumping
> methods.

You haven't got a bubble pump :-).
If you've never met them the following may be life changing. (And may
not).

Place vertical tube in water open at both ends.
Locate top of tube a designed height above water surface.
Locate bottom of tube a designed depth below water surface.

Bubble air into bottom of tube.
Design bubble size and air flow to suit various system dimensions.

Bubbles rise and expand.
Water is driven up the tube by the ascending bubbles.
Water (and air) exit from the top of the tube.

Design would be interesting.
Done with a clear tube in eg a fish tank would be fun.

   http://www.me.gatech.edu/energy/andy_phd/four.htm

   http://www.geocities.com/davidmdelaney/geyser/Sorensens-bubble-pump.html

   http://www.absalom.com/mormon/health/water-pumps.htm


  www.bubbleactionpumps.com/bubble_pump_manual/bubble_pump_manual_index.htm
       http://www.bubbleactionpumps.com/bubble_pump_manual/components_bubble_pump.htm

Einstein (really) refrigerator, which uses a bubble pump.
Included as it defines conditions for 'slug flow" of bubbles which is
most efficient mode.

       http://www.me.gatech.edu/energy/andy_phd/three.htm




   http://sims2005.idi.ntnu.no/abstracts/abstract45.php

   http://www.iop.org/EJ/abstract/0960-1317/15/3/028


       RM

2006\03\03@131209 by Peter

picon face

On Thu, 2 Mar 2006, Jason wrote:

>> Don't. Fish and people are very different and there are a number of
>> substances that can kill one while not harming the other. F.ex. alcohool
>> kills fish even at low concentrations but is relatively harmless to
>> humans even at 40 proof. This is followed by a very long list of
>> substances you likely would not like to drink but fish thrive on (or
>> in). Starting with salt water, for example.
>
> Do you know where you heard that alcohol kills fish in small quantities?

I can post a link to a news article about it, if I find it. It happens
whenever illegal distillation is performed. They have to get rid of the
mountain of boiled-off fruit mass before all the animals in the area run
around drunk and someone who matters notices.

Peter

2006\03\03@133141 by Peter

picon face

> Makes for an interesting question:  If you were floating in the water
> when a load of airbubbles were released below, would you be bouyed-up
> by the rising air/water, or sink due to the lowering of displaced
> mass?

You would sink like a stone.

Peter

2006\03\04@101659 by Russell McMahon

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> A thought has just occurred:  "Your" pressure fed pump needs gravity
> to keep the pressurised gas "above" the
> liquid fuel so that only fuel exits the tank, so presumably it
> wouldn't work in zero-G?

An operating rocket provides a very nice local "gravity" field due to
the acceleration of the craft. This is usually several g and almost
always enough of a g to cause fuel to "settle".

> And further, how does *any* liquid fuel system work in zero-G?  Is
> there some type of bladder or membrane with
> pressure on the far side which keeps the fuel in contact with the
> exit-port?

The problem is restarting in zero g. The Saturn Moon Rocket used low
level thrust from auxilliary rockets to settle the fuel in the tanks
before restart. Thrust can be provided by rockets which are not
affected in this manner by zero g conditions - eg solids or cold gas
thrusters.

{Quote hidden}

The story was essentially true albeit overhyped as all such stories
are. They are currently being used in modern launchers I believe. Name
escapes me but Google knows. The latest version of Atlas may use
these. (Now nothing like the original Atlas).



   RM

2006\03\04@101659 by Russell McMahon

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>> Makes for an interesting question:  If you were floating in the
>> water
>> when a load of airbubbles were released below, would you be
>> bouyed-up
>> by the rising air/water, or sink due to the lowering of displaced
>> mass?

> You would sink like a stone.

Like a low density stone :-).
Diving training pools use this principle to "thin" the water and make
a diver's entry softer. Getting back to the surface if one could not
get outside the bubble zone may prove excessively interesting. I
imagine that this effect may occur naturally in some locations - eg
near water falls which entrain air.


       RM

2006\03\04@101713 by Russell McMahon

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>>> Don't. Fish and people are very different and there are a number
>>> of
>>> substances that can kill one while not harming the other. F.ex.
>>> alcohool
>>> kills fish even at low concentrations but is relatively harmless
>>> to
>>> humans even at 40 proof.

Copper Sulphate kills many types of fish at (to us) very low
concentrations.

Anti freeze (ethylene glycol) is far more lethal to dogs than people.

Some human anti-biotics kill cats.

Dogs are specially sensitive to 2-4-5-T pesticide. It is therefore
used in the US in "Coyote collars" worn by sheep. A Coyote biting a
collar while attacking sheep will be fatally and rapidly poisoned.

The recommended daily maximum dose for Paracetamol analgesic (pain
killer) (extra strength Tylenol, Panadeine, Pamol,  ... many other
names) is 60% of the level at which permanent liver damage will occur
in many people. Some people are more susceptible. 12 x 500 mg tablets
will kill some people. There are better ways to die. Taking alcohol
will reduce the 'safe' dose. Each year in the US substantially more
people are killed by Paracetamol than by Cocaine. Many children are
harmed or killed by it each year but the advice given by many medical
'professionals' often fails to reflect the dangers. (If the
temperature doesn't come down just give her/him some more paracetamol
...).
The effects of an overdose can be eliminated if action is taken within
a few hours and in *some* cases far longer.




       RM


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