Level Sensor for Solenoid Valve


Does any one have any suggestions for a level sensor that would run a 120V solenoid valve?




  • I am using the Endress & Hauser level switch FTL31. Basically 24VDC so low voltage. I am in two minds whether to go for the Ex version of this level switch.

    But referring to your scenario I say the following.... 120VAC is high voltage and is steered clear of. Rather stick to 24VDC for control inputs and valves.

    I will be using 24VDC solenoid valves for distilled product.... heads, hearts and tails. In this selection I am using Ex rated solenoid valves. For my condenser water supply I am using again a 24VDC solenoid valve but not Ex rated.

  • Depends.

    Obvious caution should be used when switching 120v in proximity to potential vapor or high proof liquid.

    Simple switches can and will arc.

    Better would be to use a similar type of level switch, but have it switch a small sensing current, and use a relay to switch the solenoid.

  • edited December 2018

    Pepperl Fuchs make some nice intrinsic barriers which are basically relays that are switched by simple remote switches.

    They are built in such a way that any and all voltage are isolated from the switching side, even during malfunction. They pose zero risk of arc or ignition.

    You can use a simple magnetic reed float, or double floats if you want to maintain a fill range.

  • thanks guys ill pass this on to our electrician tim

  • edited January 2019

    Speaking level switches, my temperature transmitters (4-20mA) and level switches arrived today




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  • @richard did you go for vibrating fork level switches?

  • edited January 2019


    I have used the special 150 deg C variation.


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  • Why a fill sensor at the bottom of the tank?

    Electric elements?

  • That would be a low level switch or low low level switch if it's at the bottom.

  • It is positioned marginally above heating elements. It is there for absolute final low level detection ..... where the heating elements ultimately become exposed.

  • The heating elements are interlocked with the level switch. Once low level is detected, the coil for the power supply to heating elements is deactivated.

  • No concerns about boiling confusing the tuning fork?

  • No I certainly hope not, especially if they are correctly orientated. The forks are +- 30mm above highest part of the element as well as being furthest away from the element.

    The only time I really expect action is when the still is at the lowest and then I am happy because they will fulfil their function and protect the expensive heating elements when they become exposed.

  • I am using various liquid level sensors in our industry for a long time with no trouble. The support team is really great to help. If you are interested you can visit this website: Liquid Level Sensors @ ICON Process Controls

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