They are pressure switches activated by water flow. There is a dome-like structure inside that collapses when enough flow is present and that closes the switch. During their normal operation, they are connected to a system that uses a 3.3V signal to tell whether the switch is open or closed. This is how I know they can withstand 3.3V. In all likelihood, they could probably withstand 12V, but I do not know.
Out of the system, the switch works the same, when enough water flow is present the switch is closed, if water flow is lost, the switch opens. I want a light to indicate if an open event occurs, so my thinking was: If the switches are in series and closed with 3.3V running through them activating a relay(or transistor), as long as my circuit is wired correctly, if a switch opens, it will collapse my relay and turn on 12V to my light.
I'm sorry, I am new to electronics and am having a hard time understanding why putting the switches in series will not work? Thank you for your feedback.