Arduino Nano 33 IoT - Water/Liquid Valve

This guide explains how to control the flow of liquids like water, beer, or oil using the Arduino Nano 33 IoT and a solenoid valve. The same method works for controlling gas flow.

To open and close the valve, you can use either a relay or a MOSFET module. Both of them can only open or close the valve, nothing in between. The MOSFET module, however, makes no click, switches faster, and has no contacts that wear out. We will show you how to use each one.

Hardware Preparation

1	×	Arduino Nano 33 IoT
1	×	Micro USB Cable
1	×	Relay
1	×	Alternatively, MOSFET Module (AOD4184, LR7843 or FR120N)
1	×	Liquid Solenoid Valve
1	×	12V Power Adapter
1	×	Optionally, DC Power Jack
1	×	Breadboard
1	×	Jumper Wires
1	×	Recommended: Screw Terminal Expansion Board for Arduino Nano
1	×	Recommended: Breakout Expansion Board for Arduino Nano
1	×	Recommended: Power Splitter for Arduino Nano

Or you can buy the following kits:

DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .

Overview of Water/Liquid Valve

Pinout

A solenoid valve normally has two connection points.

Red positive pin (+): Connect this pin to the +12V terminal of your DC power supply.
Black or other colored negative pin (–): Connect this pin to the ground (GND) terminal of your DC power supply.

How Water/Liquid Valve works

The valve is usually shut. When you add 12V of DC power to its two points, the valve opens so water or liquid can flow.

※ NOTE THAT:

Some valves have a rubber ring inside that needs a minimum pressure to open the valve after you apply 12V DC. This pressure is made by the liquid flowing.

Some valves only let the liquid flow in one direction.

How to Control Water/Liquid Solenoid Valve

If the valve gets power from a 12V supply, it will open. To control the valve, you must use a relay between the Arduino Nano 33 IoT and the valve. The Arduino Nano 33 IoT sends signals to the solenoid valve through the relay. Find out more about the relay in the Arduino Nano 33 IoT - Relay tutorial.

A MOSFET module can do the same job as the relay. You can read how this module works in the Arduino Nano 33 IoT - MOSFET Module tutorial.

Relay vs MOSFET Module for Solenoid Valve

	Relay	MOSFET Module
Valve control	Open or closed	Open or closed (no PWM for a valve)
Noise from the switch	Click on every switch	Totally silent
Reaction time	Slow (milliseconds)	Very fast
Wear	Contacts wear after many cycles	No moving parts to wear
Valve power	AC or DC valve	DC valve only
Valve supply	Any voltage the relay supports	6V or more
Isolation	Yes, coil and contacts	Yes, PC817 optocoupler
Pick it for	AC valves	12V DC valves that open and close often, or quiet places

A solenoid valve is either open or closed, so the MOSFET module does not give you extra control here. Choose it when you want no clicking and a longer life for the switch. For an AC valve, use the relay.

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Arduino Nano 33 IoT Code

The code below repeatedly opens the water valve for five seconds, then closes it for five seconds.

/* * This Arduino Nano 33 IoT code was developed by newbiely.com * * This Arduino Nano 33 IoT code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano-iot/arduino-nano-33-iot-water-liquid-valve */ #define RELAY_PIN 2 // The Arduino Nano 33 IoT pin connected to the water valve via the relay // The setup function runs once on reset or power-up void setup() { // initialize digital pin D2 as an output. pinMode(RELAY_PIN, OUTPUT); } // The loop function repeats indefinitely void loop() { digitalWrite(RELAY_PIN, HIGH); // open valve 5 seconds delay(5000); digitalWrite(RELAY_PIN, LOW); // close valve 5 seconds delay(5000); }

Detailed Instructions

If you are new to the Arduino Nano 33 IoT, be sure to check out our Getting Started with Arduino Nano 33 IoT tutorial. Then, follow these steps:

Connect the components to the Arduino Nano 33 IoT board as depicted in the diagram.
Use a USB cable to connect the Arduino Nano 33 IoT board to your computer.
Launch the Arduino IDE on your computer.
Select the Arduino Nano 33 IoT board and choose its corresponding COM port.
Copy the code above and paste it into the Arduino IDE.
Click the Upload button to compile and send the code to your Arduino Nano 33 IoT board.
Check to see if the water is flowing.

Code Explanation

The Arduino Nano 33 IoT code above explains each line clearly. Please check the comments in the code.

How to Control Water Valve with MOSFET Module

You can also open and close the 12V solenoid valve with a MOSFET module in place of the relay. The board only needs to send HIGH or LOW to it.

The relay and the MOSFET module use different pins on this page: D2 for the relay and D9 for the MOSFET module. So the MOSFET wiring has its own code below.

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Arduino Nano 33 IoT / Valve / Adapter	MOSFET Module
Pin D9	PWM
GND	GND
12V adapter +	+ terminal
Valve red wire (+)	+ terminal (together with the adapter +)
Valve negative wire (−)	LOAD terminal
12V adapter −	− terminal

The valve has a coil inside. Put a 1N4007 or 1N5819 diode across the valve wires, with the stripe (cathode) on the valve + wire. This protects the module from the voltage spike when the valve closes.

Arduino Nano 33 IoT Code

The code below follows the same idea as the relay code: HIGH opens the valve for five seconds, then LOW closes it for five seconds. It just uses pin D9.

/* * This Arduino Nano 33 IoT code was developed by newbiely.com * * This Arduino Nano 33 IoT code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano-iot/arduino-nano-33-iot-water-liquid-valve */ #define MOSFET_PIN 9 // The Arduino Nano 33 IoT pin D9 connected to the PWM pin of the MOSFET module // The setup function runs once on reset or power-up void setup() { pinMode(MOSFET_PIN, OUTPUT); // set the pin as an output } // The loop function repeats indefinitely void loop() { digitalWrite(MOSFET_PIN, HIGH); // open the valve for 5 seconds delay(5000); digitalWrite(MOSFET_PIN, LOW); // close the valve for 5 seconds delay(5000); }

Do not use PWM or fade code with a solenoid valve. A valve must get full power or no power. This is why we do not use the fade code from the MOSFET module tutorial here.

Detailed Instructions

Wire the MOSFET module and the valve as shown in the diagram.
Connect the Arduino Nano 33 IoT to your computer and open the Arduino IDE, as in the relay Quick Steps above.
Copy the code above, paste it into the Arduino IDE and upload it.
Plug in the 12V adapter.
The valve opens for five seconds, then closes for five seconds, with no relay click.

※ NOTE THAT:

The MOSFET module is for DC only, and the valve supply must be about 6V or more. If your valve runs on AC, keep the relay.

Video Tutorial

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