I need to buy a level switch for a quench tower water drainage system. I intend to use its output directly to open a solenoid valve to drain the tank when the switch detects water and close it afterward when the water recedes. I have identified make and model of a level switch I think is good. But the manufacturer provides multiple types of electrical outputs. It would be great if someone could advise on which of the following type is best for a simple level switch - solenoid valve circuit.

  1. Relay
  2. NAMUR
  3. Transistor
  4. 2-wire

P.S: I am a newbie regarding electrical stuff. I'll consult a friend who will help me to design the circuit, but I just need to place the order for the level switch.

  • 1
    $\begingroup$ Welcome to Engineering.SE . Could you add a link to the family of the sensors that you like? Could you tell us what you're going to connect the sensor to? $\endgroup$ Feb 20, 2019 at 5:43
  • $\begingroup$ Can you share the make and model of the Level Switch? Can you share the specification of the Solenoid Valve? $\endgroup$ Feb 21, 2019 at 1:55
  • $\begingroup$ What are the current and voltage requirements to "directly to open a solenoid valve"? If these matched those of the "relay" option you might be able to not use a relay itself, but chances are pretty high that you will just have to use a relay or transistor in the middle and go with the appropriate output option. $\endgroup$
    – Abel
    Apr 5, 2021 at 2:06

1 Answer 1


How about using a latching solenoid valve like the following?

enter image description here

1/2" Magnetically Latching Solenoid Valve DC 6 V

Use a h-bridge driver to switch on and off the valve. Below is one that I have used most recently.

DRV8833 Dual Motor Driver Carrier \ enter image description here


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    $\begingroup$ The only reason to add the additional complexity would be to conserve energy but this does not seem to be an issue for the OP. $\endgroup$
    – Transistor
    Aug 13, 2019 at 20:53

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