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'[OT] Re: Home Automation - Water Volume Measuremen'
1999\01\10@222220 by James Cameron

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Luyen Tran wrote in HTML:
> I'm going to do a 'Home Automation' project that controls light,
> temperature, yard watering ...

On yard watering, my wife and I were discussing this on the six hour
drive back from our farm on the weekend, and we decided that "time"
isn't good enough as data for deciding when to water, and that
"moisture-level" of the soil should be the determinant.

Then we thought that it should be proportional control, so that the
moisture level determines the duty cycle or ratio of watering/not-
watering periods, so that the plants get to trust their environment and
thrive accordingly.

Then we remembered that the ants tend to crawl up the watering pipes,
and so the volume of water delivered will vary over time.  Sure, the
moisture level feedback would help to fix this, but not rapidly.  I'd
prefer to design the system so that a "volume" of water is delivered
rather than a duty cycle of valve opening.

So does anyone know any water volume measuring techniques suitable for
connection to a PIC microcontroller?  Domestic hobby level stuff, not
industrial control.  Yet.

--
James Cameron                                      (spam_OUTcameronTakeThisOuTspamstl.dec.com)

OpenVMS, Linux, Firewalls, Software Engineering, CGI, HTTP, X, C, FORTH,
COBOL, BASIC, DCL, csh, bash, ksh, sh, Electronics, Microcontrollers,
Disability Engineering, Netrek, Bicycles, Pedant, Farming, Home Control,
Remote Area Power, Greek Scholar, Tenor Vocalist, Church Sound, Husband.

"Specialisation is for insects." -- Robert Heinlein.

1999\01\10@224136 by Gerhard Fiedler

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At 14:10 01/11/99 +1100, James Cameron wrote:
>Then we remembered that the ants tend to crawl up the watering pipes,
>and so the volume of water delivered will vary over time.  Sure, the
>moisture level feedback would help to fix this, but not rapidly.  I'd
>prefer to design the system so that a "volume" of water is delivered
>rather than a duty cycle of valve opening.

maybe you can hinder the ants crawling up? something like a "siphon"
(german, didn't find it in the dictionary -- goes down and up again, so
that there's always water in the bend) maybe, in some central places in the
main pipes.

difficult to measure volume flow if the active cross section of the pipe is
not known. and if the ants can considerably change your cross section, they
sure can block any moving parts, too (like a paddle wheel to measure the
speed -- but you still wouldn't know the cross section, =if= the ants
change it). are you sure that the ants change the volume flow so much you
have to care about?

ge

1999\01\10@230415 by James Cameron

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Gerhard Fiedler wrote:
> maybe you can hinder the ants crawling up? something like a "siphon"
> (german, didn't find it in the dictionary -- goes down and up again, so
> that there's always water in the bend) maybe, in some central places in
> the main pipes.

Australian conditions.  Temperatures up near 40 degrees centigrade are
fairly normal, agricultural distribution pipes are matt black PVC, the
pipes may boil themselves dry on a hot day and a bend containing water
would probably attract ants anyway.  ;-)

> difficult to measure volume flow if the active cross section of the
> pipe is not known.

Good point.  I was thinking of a distribution layout like this;

Water Supply --> Filter --> Flow Measurement --> Valves

                                               |       |       |
                                               v       v       v
                                               Filters
                                               |       |       |

First filter is to remove things from the water that would annoy the
flow measurement and valves.  Last set of filters after the valves would
be to prevent ants from crawling back into the valves and flow
measurement.

The other "problem" is that after the valves for regions of garden or
orchard the distribution pipes go to outlets of various sizes, which are
adjustable.  Gotta figure out how to rig it so that an adjustment of one
outlet doesn't affect the flow from another.

--
James Cameron                                      (.....cameronKILLspamspam@spam@stl.dec.com)

OpenVMS, Linux, Firewalls, Software Engineering, CGI, HTTP, X, C, FORTH,
COBOL, BASIC, DCL, csh, bash, ksh, sh, Electronics, Microcontrollers,
Disability Engineering, Netrek, Bicycles, Pedant, Farming, Home Control,
Remote Area Power, Greek Scholar, Tenor Vocalist, Church Sound, Husband.

"Specialisation is for insects." -- Robert Heinlein.

1999\01\11@025417 by Gerhard Fiedler

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At 14:52 01/11/99 +1100, James Cameron wrote:
>Good point.  I was thinking of a distribution layout like this;
>
>Water Supply --> Filter --> Flow Measurement --> Valves
>
>                                                |       |       |
>                                                v       v       v
>                                                Filters
>                                                |       |       |
>
>First filter is to remove things from the water that would annoy the
>flow measurement and valves.  Last set of filters after the valves would
>be to prevent ants from crawling back into the valves and flow
>measurement.
>
>The other "problem" is that after the valves for regions of garden or
>orchard the distribution pipes go to outlets of various sizes, which are
>adjustable.  Gotta figure out how to rig it so that an adjustment of one
>outlet doesn't affect the flow from another.

if you can make the outlets the flow limiting part, and the flow speeds
leading to them are not too high, and you can keep the pressure constant
(where you would put your flow measurement), then each outlet gets constant
flow, only depending on the size of the outlet. adjustments on one outlet
wouldn't affect the flow in other outlets. the error in that would be the
loss of pressure along the line from the constant pressure to the outlet
(which depends on the flow speed and the cross section). the ants would
still make an error, but maybe small.

otherwise i don't know about "cheap" non-professional ways to measure flow.
paddle-wheels, measuring (flow speed depending) cooling of a heated
resistor, ... depends on your mechanical skills, amount of fiddle-time you
want to spend :-)


>"Specialisation is for insects." -- Robert Heinlein.

some of them are pretty universal ;-)

ge

1999\01\11@043803 by John

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Hello James & PIC.ers,

Would you like to tell me (/us) how you will go about the `moisture-content
measurement'  side of this control loop?
..
If you hadn't yet thought about it, there are some devices for this on the
market (I have one here).
Perhaps such a thread should go off-piclist, as it is definitely OT.

Best regards,   John


{Quote hidden}

e-mail from the desk of John Sanderson, JS Controls.
PO Box 1887, Boksburg 1460, Rep. of South Africa.   Tel/fax: Johannesburg
893 4154
Manufacturer & purveyor of laboratory force testing apparatus, and related
products and services.

1999\01\11@095605 by WIL REEDER

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Hello again James; and Luyen

We have a watering system at the summer getaway and at home. Home has grid
power so we use x10 and the getaway has solar/wind where we use a bilge
pump and a bomb timer. Both systems have a rain sensor in them and it cuts
off the power supply to the valves or pump. This seems to work well and
volume has not really been an issue in the 5-6 years we've been doing this.
The rain sensor is a series of fabric disks that expand when wet and open a
contact, as they dry the contacts close, so the thing can just go in the
line to the valves or small pump. They are readily available from Toro. If
accurate amounts of water are a requirement for some reason... what about
pumping a gravity feed tank to a measured volume and water from there?. We
really find that maintenance once or twice a season will keep the system at
full capacity.
Hope this helps


Wil Reeder
.....teachtechKILLspamspam.....bc.sympatico.ca
Vancouver,Canada
Faster horses, younger women, older wiskey, and more money!
----------
{Quote hidden}

SNIP

1999\01\11@102021 by Morgan Olsson

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>, agricultural distribution pipes are matt black PVC

Really PVC?! - Here we only use PE in the pipes
(Much longer life in the sun, better freeze survival, and no piosonous to
burn at life end)


If it is drip irrigation you probably want to add nutrition too.
There are theese relatively cheep water flow driven nutrition pumps.
Theese are pulsating cylinter type pumps, made of plastic.
If possible to add a magnet on the moving part, and a hall sensor at the
case, you will have one pulse per x volume of water!

Water Supply --> Filter --> Nutrition pump --> Valves
                              ^    Magnet        |       |       |
                             /       :           v       v       v
                            /        :           Filters
                           /         :           |       |       |
               Nutrition tank  Magnetic sensor

/Morgan
       Morgan Olsson                   ph  +46(0)414 70741
       MORGANS REGLERTEKNIK            fax +46(0)414 70331
       H€LLEKS           (in A-Z letters: "HALLEKAS")
       SE-277 35 KIVIK, SWEDEN               @spam@mrtKILLspamspaminame.com
___________________________________________________________

1999\01\11@102028 by Morgan Olsson

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>Hello James & PIC.ers,
>
>Would you like to tell me (/us) how you will go about the `moisture-content
>measurement'  side of this control loop?
>..
>If you hadn't yet thought about it, there are some devices for this on the
>market (I have one here).
>Perhaps such a thread should go off-piclist, as it is definitely OT.

Sensors are probably considered very on-topic for controllers, right?   ;)

/Morgan
       Morgan Olsson                   ph  +46(0)414 70741
       MORGANS REGLERTEKNIK            fax +46(0)414 70331
       H€LLEKS           (in A-Z letters: "HALLEKAS")
       SE-277 35 KIVIK, SWEDEN               KILLspammrtKILLspamspaminame.com
___________________________________________________________

1999\01\11@111339 by Peter L. Peres

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Hello,

> Re: hobby level water volume transducer

 imho, a caliper (to read the pipe diameter) an electronic pressure gauge
for 0-10 at and a timer is all you need... I know many systems with moving
parts in the water from close up (and I'm in service/repair ;).

Peter

1999\01\11@115826 by Alice Campbell

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Hi jim,

> So does anyone know any water volume measuring techniques suitable for
> connection to a PIC microcontroller?  Domestic hobby level stuff, not
> industrial control.  Yet.
>
i use a 5-gallon bucket and a stopwatch.  the flowrate is 5/minutes
to fill bucket.  armed with the flowrate, you can then use the pic to
time the sprinklers.  this assumes you just leave the valve in one
position.

alice
alice

1999\01\11@180847 by Russell McMahon

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I just purchased a manual garden watering valve (no PICs in it). It
is apparently (judging from the label, noises it makes when you
adjust it
and a little deduction) water driven and positive displacement so
that it drives itself off based on true volume of water passed. Such
a valve could probably be persuaded to run continually without
shutting
off and give meter pulses either from the positive displacement rotor
or some other part of the works.

Mine cost is Hozelock (lok?) brand - allegedly UK made - $NZ20 from
"The Warehouse"
so they are probably available cheaply in Oz etc.

Electronic versions are available for 5 times as much and very
possibly contain a PIC.
A home built (PIC based of course) positive displacement meterer
could be built from scratch but at $20 the premade version sounds
like a good starting point. (I could be persuaded to investigate the
intermnals of mine with very little persuasion :-))


regards

   Russell McMahon



{Original Message removed}

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