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Electronics Water flow measuring system that trips a switch every X Litres any ideas?

Discussion in 'Modding' started by tacticus, 22 Jun 2007.

  1. tacticus

    tacticus What's a Dremel?

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    Well heres the deal
    i am currently in the process of acquiring the parts to replace the watering system here with something a wee bit better

    I have an asus wl-hdd running openwrt and owfs and many one wire devices on the way this i can handle

    but of course if you are going to build a watering system using a linux box to control it why not go all the way

    so i decided to grab one of http://www.hobby-boards.com/catalog/product_info.php?cPath=24&products_id=42 and find out someway to hook it up into a unit that will let me measure water consumption by the garden and work out which sections use the most water and have a slightly easier time of detecting leaks


    but if this is the wrong way of counting water consumption please tell me more :)

    eventually i want a system that will water the garden automagically when the ground needs it and if it rains or looks like rain (pressure\humidity\solar radiation info) for it to delay\skip watering the yard


    To explain this quest for shinyness this i will pass you to the wise words of Mr. Adams
    "I am rarely happier than when spending an entire day programming my computer to perform automatically a task that it would otherwise take me a good ten seconds to do by hand."
     
  2. jgrade

    jgrade What's a Dremel?

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    There are many ways to measure the water flow, but the two most popular (electronic methods) are with a paddle wheel or with ultrasonic. The ultrasonic can be added with a "saddle" type mount. The trick will be to find the type of device that does not cost too much and can be modified. If you are watering a garden I would choose a paddle wheel and put it in-line with the main water flow. These devices use a magnet and FET to calculate the flow of water.
    I have used many over the years in my business. I prefer the type that will give instant as well as a totalizer. This of course is where your programming will come in handy. If you hack an inexpensive paddle wheel (or build your own) you can intercept the signal from the FET and use the pulse to count turns. Some even give you the option to connect to the pulse directly, but those are usually expensive. A down and dirty way to measure flow when trying to calibrate your software is to fill a known volume while counting pulses. It may not be completely accurate but enough for a garden.
     
  3. tacticus

    tacticus What's a Dremel?

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    Excellent i will definatly head over to the plumbing supplies place on monday and try and find one
     
  4. Moriquendi

    Moriquendi Bit Tech Biker

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    You could build a japanese water clock and have it hit a microswitch every time it 'THUNK's, that would be a waterpiece as well as measuring flow.

    Moriquendi
     
  5. profqwerty

    profqwerty What's a Dremel?

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    You could check the pressure of the water; it will be proportional to the water flow rate. This would require quite a bit of calibration though.
     
  6. ConKbot of Doom

    ConKbot of Doom What's a Dremel?

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    If you added a water pressure regulator to the system, then the pressure should be fairly constant, and then time would the the only variable in what comes out of the hose once he has a fixed hose setup...
     
  7. jgrade

    jgrade What's a Dremel?

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    Pressure and flow are not proportional. Look at the curve on a pump spec and you will see. Take a garden hose and cap the end. You will have static pressure but no flow. Now uncap the hose and you will have flow at the same pressure (or just about). Another example. Take your hose bib and add one of those splitters with 2, 3 or 4 connections. Now run a hose to each. Turn all of them on full. The pressure is the same, but the flow from each is much less. I think your confusing flow and velocity; two very different things.
     
  8. jgrade

    jgrade What's a Dremel?

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    PRV's are expensive and would not work well for this situation. Look at the post above this one. Pressure and flow are not the same. You can have flow at any pressure. Flow can change from moment to moment due to demand on the system. Most delivery systems are shared so if someone else has a large demand then the rest of the flow will be reduced.

    Flow meters do not measure pressure because it is irrelevant.
     
  9. harvy

    harvy Minimodder

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    If you will be hooking it up to a PC then why not try this:

    Use your bog standard flow meter from a WC kit.
    Use software to calculate the amout of water.
    Use a realy/controller to open/close a solenoid ( you may be able to get hold of a second hand school controller. I cant remember what they are called but basicly was a pannel hooked up to mains and comp. was prob 12 or so ports and prob same number of lights. you would then write a script to turn on the ports and lights as required. you should be able to hook up the port to a solenoid)
     
  10. Skulldragger

    Skulldragger What's a Dremel?

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    So, I'm taking apart a 3 wire fan and it crosses my mind that the 3rd wire is for reporting speed. This means that it generates pulses which are read by the MB, right? Would the guts of a fan, or a fan in an acrylic box or some such work to report pulses which could be read by either a PIC or serial/lpt port? If so then you may be able to wright a simple program that will read the pulses (as suggested above) and translate that into what ever value you are needing.

    Just a thought, would like to know if it would work myself!
     
  11. harvy

    harvy Minimodder

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    Cant seem to find an example of the controller, but details are outlined on here.

    Basicly if you take one of these:

    standard flow meter

    Hooked up to your comp ( in the case of the flow meter above ive got mine through a sensor hub and mCubed). through fan port or other hard ware monitoring device.

    From there use the pc to calculate the flow if it appears as RPM.

    Use the controller from the top of this post to read in this flow value and adjust pump/valve as required.

    Will see if i can find the controller online somewhere.. im sure someone must be sellin one on ebay...
     
  12. tacticus

    tacticus What's a Dremel?

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    Thats pretty much the plan except i intend to have the relays\controller further away from the computer using a 1wire system http://en.wikipedia.org/wiki/1-Wire

    the actual controller will be an Asus wl-hdd http://wiki.openwrt.org/OpenWrtDocs/Hardware/Asus/WL-HDD running openwrt and OWFS (see 1-wire link)

    this connects onto the 1wire network using a usb adaptor http://www.hobby-boards.com/catalog/product_info.php?cPath=23&products_id=1503 and the 1wire "microlan" will have multiple switches and sensors all through it

    pretty much though i think i will be sticking to non home made stuff for this as it will be connecting to the main water supply
    http://www.hobby-boards.com/catalog/product_info.php?cPath=24&products_id=42 is the unit that counts the pulses

    that alphacool product is a great idea unfortunately it just probably wont handle the flow rate of this setup but the local farm watering mob are getting a unit in (much like what jgrade described below) for me to look at and even test once my stuff gets here and that part is not currently costing me anything.
    though they did ask if i could give them pics and details about it so they can get some of it to play with :)
     
  13. jgrade

    jgrade What's a Dremel?

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    This is what you are looking for or want to build. Check out this link (the Digi-Flo). Blue White is a reputable company. I don't have pricing, but without the electronics and display, it should be pretty inexpensive.

    As a side note check out the 5 or 6 part article in Nuts and Volts magazine on how to build a one wire weather station with micro controller. It may give you some help. One of the instruments measured was wind speed using a FET just like the paddle wheel for flow.
     
    Last edited: 3 Jul 2007
  14. Spaceraver

    Spaceraver Ultralurker

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    Do post a schematic when youre further down the road. Btw, could those I-buttons that latches be used for a car? both as door and ignition.
     

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