Extra port changes everything. Three ports mean directional control, not just on/off switching. Flow gets diverted between pathways or mixed from separate sources. Two-way valves can’t handle that kind of routing complexity.

Safety requirements drive this decision mostly. NC valves block the main flow when power is off, redirecting it to the exhaust, making for a good fail-safe setup. NO models keep flowing until energized to redirect. Consider what you want your model to do during power failures.

Universal valves can be piped as either normally closed or normally open, plus they handle diverting and selecting functions. However, the maximum working pressure is typically lower than dedicated NC or NO models. These versatile 3-way solenoid valves are cost-effective when you need operational flexibility but not maximum pressure ratings.

Speed versus efficiency trade-off here. Direct-acting units react faster and work without a pressure differential, but they’re power hogs on larger orifices. Pilot-operated versions utilize system pressure to help, conserve electricity, and move a greater volume.

Brass machines are easier and cost less for standard industrial work with moderate conditions. Steel handles nasty or corrosive environments better – chemicals, saltwater, high heat. Brass degrades in harsh conditions while steel keeps working longer term.