Problem connecting Arduino to Darlington transistor and Humphrey H041E1 solenoid

I'm attempting to connect an Arduino with a Darlington Transistor and a Humphrey Solenoid. The Solenoid is rated at 18 M ohm internal resistance, which i do not understand how this works. In addition, does the darlington transistor have a flyback diode for back emf. If the Solenoid is rated at 5V and around 330 mA . Does the Darlington transistor require a 12V source?

For which voltage is the Humphrey H041E1 rated ? There are probably 5V, 12V and 24V versions of it.

There is a pdf document here (sorry for the terrible link):

It tells that it needs 120mA at 5V.

Darlington transistors do not have a flyback diode. You need to use a flyback diode parallel with the solenoid.

You also need a resistor from the Arduino pin to the base of the darlington transistor. You can start with 4k7 (or 1k to 10k).

It's rated at 5V

Another question is, what does it mean by Indirect Acting In-Line Solenoid Valves? What i'm most concerned is what indirect means as well as what does N/C or N/O mean. I know it means normally closed and normally closed, but what does this mean when it is hooked up?

I'm not sure, but I think that indirect acting uses a small solenoid coil to turn on and off a strong air pressure by using the air pressure itself. In-line could be that they can be placed next to each other on a special base plate.

For example the water inlet solenoid valve of a washing machine is indirect acting to withstand the water pressure.

Makes sense because i tried turning it on without air and never heard a click. Thanks :D