Solenoid Operated Valves

De-energized; 2 to 1 - full flow, pressure difference through the pilot orifice holds the main poppet open. 1 to 2 - restricted flow, main poppet pressure biased onto its seat, pilot orifice open.
Energized; 2 to 1 - No flow, pilot orifice closed, main poppet pressure biased onto its seat. 1 to 2 - full flows when solenoid force overcomes.

Normally Closed
De-energized; 2 to 1 - no flow, pilot orifice closed, main poppet pressure biased onto its seat. 1 to 2 - full flow when spring force is overcome.
Energized; 2 to 1- full flow, pressure difference through the pilot orifice holds the main poppet open. 1 to 2 - restricted flow, main poppet pressure biased onto its seat, pilot orifice open.