Water flow meters for archival washers

Discussion in 'Darkroom Equipment' started by Tom Kershaw, Aug 13, 2010.

  1. Tom Kershaw

    Tom Kershaw Subscriber

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  2. Marco B

    Marco B Member

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    Just take a bucket of known size (e.g. 2 or 5 litre), open up the tap as you would for archival washing, and collect the water coming out of it in the bucket... Use a stopwatch to time how fast it fills up and you will know the flow rate in litres / second. Multiply that with your normal washing times, and you are done...

    Or do you really need millilitre precision? :confused:
     
  3. Tom Kershaw

    Tom Kershaw Subscriber

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    Marco,

    If I install an accurate tap control which I can mark off at a known flow rate via the water in bucket method then yes, that is certainly an option.

    Tom
     
  4. RalphLambrecht

    RalphLambrecht Subscriber

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  5. Marco B

    Marco B Member

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    Tom, there is nothing wrong with such a flow meter, they will be highly accurate if properly calibrated. But I think it is overkill. A properly maintained modern municipal water supply is pressurized using large pumps (at least here in the Netherlands) and should deliver fairly constant results, although I realize there may be demand peaks influencing flow rate...

    A normal tap has a metal thread that should give pretty consistent results if you count the number or "turns"... just try it out and see how repeatable it is over the course of a day. You can always go the "high-tech" :wink: option afterwards...
     
  6. Tom Kershaw

    Tom Kershaw Subscriber

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    Marco,

    There is the water pressure of the Nova tank itself to be taken into account.

    Ralph,

    I have a Nova Academy 3 print washer (20x24")

    Tom
     
  7. Photo Engineer

    Photo Engineer Subscriber

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    Tom;

    There are small ball flow meters that are very inexpensive that could be used. IDK any names OTOMH, but we used to have a full kit of these. They have a small knob that moves a conical needle in and out of a tapered conical chamber. The water pressure is adjusted by the distance of the needle and the ball floats on the incoming water and rises to indicate the rate of flow.

    They are small, about 1/2 inch on each side and about 3" long. They have standard threaded connectors at each end for easy attachment to equipment. The only drawback is that these must be in a vertical position to work.

    We had them on every tank of chemicals in our main testing labs so that they knew precise wash and replenishment rates, and this data was used to derive the data sheets you see posted on Kodak publications.

    PE
     
  8. Tom Kershaw

    Tom Kershaw Subscriber

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    PE,

    Thanks for this, I'll investigate further.

    Tom
     
  9. Tom Kershaw

    Tom Kershaw Subscriber

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    Like this: http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=3610199 ?

    Tom
     
  10. Reinhold

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  11. Photo Engineer

    Photo Engineer Subscriber

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  12. Martin Aislabie

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  13. RalphLambrecht

    RalphLambrecht Subscriber

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    I'm afraid that's the UK for you.
    It has always been more expensive to live on an island. :sad:
     
  14. George Collier

    George Collier Member

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    I don't know if this works for everyone, but my Gravity Works print washer has an exit hose, running from the bottom, and an overflow at the top. It has a click pincher on the exit hose to control the speed of the exit flow. The first time I used it, I set the pincher at several different clicks, measured the exit with a container, as suggested, then calculated the time to completely fill (or exchange) the water in the tank, and selected a click setting on the pincher that gives me several (I think 6, it's been awhile) changes of water in 45 minutes. I just use the click setting for #3, and adjust the supply so that I have just a dribble overflowing. My temp control valve has an unmeasured flow control, so this is easy.