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water alarm

Discussion in 'General Electronics Discussion' started by adk315, Oct 21, 2010.

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  1. adk315


    Jul 29, 2010
    Need help with a water alarm for diesel fuel tank

    Will be using a probe that consist of two metal plates about 1/8" square mounted on a insulator with an air gap of 1/8", the probe will be mounted at the bottom of the tank. When the water level reaches the probe plates, continuity is made and a relay will sound an alarm. Since the continuity is very low I need some help with a holding circuit that will be able to close the relay, also the operator will have to reset power to clear the alarm.

    Thank you

  2. pblokhuis


    Jan 7, 2019
    You haven't said what voltages you are putting through the plates but if it exceeds 1.5VDC then it can potentially cause a spark with sufficient energy to cause ignition. It just sounds like a bad idea to put electricity into a diesel fuel tank.
    Is there a reason why you wouldn't go with the tried-and-true approach of using a simple float switch powered by safe low energy levels? This is something best left to those who specialize in the field of hazardous environments. We have an off-the-shelf product that will do exactly what you need. Please check out this Intrinsically Safe tank level alarm that will save you a lot of work.
    davenn likes this.
  3. Bluejets


    Oct 5, 2014
    Don't know about that.
    Common practice to have a variable resistor type gauge in petrol tanks supplied by regulated 5v.
    Not to mention pressure motors completely submerged in petrol tanks.
    I'd say petrol would be more volatile than diesel.

    I'm just curious why there would be the need to look for water in the diesel tank. i.e. would it not be better to find where any water would be coming from and seal it up.

    Other than that, a simple darlington transistor arrangement should suffice with many many circuits out there already.
    Perhaps a peek in here will show something.

    Look under ebook 2 .....101-200 ccts on the left index.....transistor circuits......then look for water level detectors ....a couple shown.
    Last edited: Jan 7, 2019
  4. Kiwi


    Jan 28, 2013
    Water level detection in diesel tanks is very common in automotive applications. Many engines have a fuel filter with a pair of contacts in a glass or plastic bowl on the bottom of the filter assembly. Some of the newer ones have a three terminal electronic sensor to detect water. Condensation is a common source of this water. Water is very damaging to the fuel system, especially the injectors.
  5. Bluejets


    Oct 5, 2014
    Fair enough....I assume condensation from machinery parked outdoors.
    Never seen it in the generator systems before.
    Then again they are mostly indoors and the outdoor one probably just depends on the water trap.
    The latter being more practical I would imagine.
    Seen alarms go off before and no one takes a bit of notice.:rolleyes:
    Cheers Jorgo
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