Hi,
I am using a solenoid valve with DC pumps to inflate a balloon. I am having difficulty understanding how this actually works. What is HIGH doing and what is LOW doing? Does anyone have experience with this?
Connect the pump to port #3. Connect the balloon to port #2. Send power to the valve to inflate the balloon.
You cannot control the valve or the pump with Arduino digital output pins. The recommended maximum current into or out of a pin is 20mA. The valve requires 240mA at 5V (see the data sheet). You will need a transistor to drive the valve. I would suggest a logic level MOSFET driver.
MOSFET valve driver
Send a HIGH to the digital output to turn on the MOSFET to energize the valve and inflate the balloon, a LOW to turn the MOSFET off and the valve should hold the pressure in the balloon.
The pump will need a similar driver since it will also require much more than 20mA.
Here is the circuit I'm using that now works. Looks like my Valves were actually 6V so I'm running on a an external power supply via the power input and using VIN pin to make the arduino adjust to the voltage.
Your fuzzy pictograph is missing a large portion of the circuit. Posting an annotated schematic would be a big help. Your 5V goes into the clouds doing nothing. Important rule is "A Power Supply the Arduino is NOT! This may be your lucky day and you have not blown the Arduino.
What really matters with your valves it HOW MUCH TIME they will be active and how often they will be active. The solenoid coil produces heat as well as magnetism. Heat is what will kill your solenoid.
If you are only operating a solenoid for a few seconds every minute, then 12 volts will work fine.