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Absorption detector.

Discussion in 'General Electronics Discussion' started by Krystian, Apr 12, 2017.

  1. Krystian

    Krystian

    5
    0
    Apr 12, 2017
    Good Morning,


    I am going to build a device to detect the physical state of water. I came up with an idea, that the easiest solution is to measure the intensity of the reflected wave, which length is 4150nm. According to http://www.nature.com/nature/journal/v439/n7073/fig_tab/nature04415_F1.html there is a significant difference in absorption of liquid and solid water. The device is created for ordinary applications, so it doesn’t need to be as sensitive as ones for laboratory use. I found that there is a possibility to buy a thermopile with 4.3 μm band-pass filter, but there is a lack of 3050nm detectors. The device should also have the second reference detector, but I don’t know which wavelength will be the most desirable. Another point is selection of IR emitter that will match the detectors, I am not sure which one should I buy.

    Or maybe there is a completely different solution that is easier/better than presented above?

    I thought about opto elements below:


    http://www.hamamatsu.com/jp/en/L13201-0430C.html


    http://www.hamamatsu.com/jp/en/product/category/3100/4007/4219/T11361-01/index.html


    http://www.hamamatsu.com/jp/en/product/category/3100/4007/4219/T11361-05/index.html



    Do you think it will work?

    Best regards,
    Krystian
     
  2. shrtrnd

    shrtrnd

    3,672
    453
    Jan 15, 2010
    I'm unsure of what it is you're trying to do. What exactly do you mean by 'detect the physical state of water'?
    Are you looking for contamination, or specific contamination of some type?
    Mineral or biological, or both?
    Clarity of the water sample physically?
    What exactly is your application?
     
  3. Krystian

    Krystian

    5
    0
    Apr 12, 2017
    We are gonna detect the ice and the water over a concrete. The thing is that the state of H20 dependences not only on the temperature but on volume and pressure too. In this case we need preparing some kind of detector wchich can give us an answer if it's water or ice.

    We will be very glad for any other ideas of detecting the ice and water.
     
  4. shrtrnd

    shrtrnd

    3,672
    453
    Jan 15, 2010
    Sounds to me like maybe you should be checking into a pressure sensor of some type.
    The pressure on the sensor would increase when the water turns to ice, if in the proper sensor pressure range, it
    should also indicate your volume and pressure changes between the water state of liquid or solid.
    It sounded like you were actually trying to analyze a water sample in your original post.
    Hopefully you'll see follow-up posts from other forum members here, now that we know what you meant by the
    'state of water.'
     
  5. Alec_t

    Alec_t

    2,691
    712
    Jul 7, 2015
    Does the sensor have to be remote from the ice/water, or can the sensor be in contact with it?
     
  6. Krystian

    Krystian

    5
    0
    Apr 12, 2017
    shrtrnd, Alec_t,

    The problem is that the sensor cannot be in contact with the "water". I thought about measuring the pressure and the temperature, but... for example the salt can melt the ice and we receive a water (we don't know the dependances on the pressure and the temperature). You can imagine other situation: sunny day and so on.

    Krystian
     
  7. shrtrnd

    shrtrnd

    3,672
    453
    Jan 15, 2010
    You've got a pretty tricky situation there. I can't think of anything inexpensive on the market to do what you want that doesn't actually contact the water. I'll think about this and post other ideas if I think of any.
    I used to work for a cement company. The issue when we made the mixture, was to ensure that water on the cured concrete would not degrade the quality. We ran continuous test samples through an autoclave and then tested it for hardness and exploded samples in a 'bomb' test chamber (which was an expensive device).
    Let me ask your application:
    It SOUNDS like you are trying to ensure that the water used over the curing, laid concrete is maintained immediately after laying the pad, doesn't dry out while the concrete is curing. Is that correct?
    Or are you trying to determine 'absorption' of water over already cured concrete due to rain or other environmental exposure?
    In this country, the cement manufacturer is required to maintain records of the mixture they supply to users, that meet specifications. I'm wondering if the basic information you require can be obtained from the manufacturer, or
    if you are a contractor that is trying to ensure that your work is not degraded after you lay it.
    I think that knowing the reason why you want to run this test, might help us determine the best method for your application.
     
  8. Krystian

    Krystian

    5
    0
    Apr 12, 2017
    Thank you for your answer shrtrnd!

    My aim is totally different. I am going to detect the water or ice on the beton surface and with a view to that I'm going to control the electronic device.

    I don't need to catch every drop of water or ice. Just I need more or less know what kind of substance is on the surface of beton. I would like to measure it with frequency min 100-200Hz and it will still be fine if I receive the result as a average of 10-20 measurments.

    Cheers,
    Krystian
     
  9. Krystian

    Krystian

    5
    0
    Apr 12, 2017
    Up.
     
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