To open a steam valve you can use various methos. The most common opening type is to use a steam valve knob. But you also see that on some espresso machines the steam valves are operated with a solenoid valve. For the solenoid valve operated valves you should look on the solenoid valve page.
Every espresso machine brand uses their own style of steam valve. Some steam valves are opened when you push down a lever, for instance on some espresso machine models made by Nuova Simonelli, Victoria Arduino, La Spaziale and Vibiemme.
More traditional types of steam valves are the open and closing of a steam valve when you turn it right or left. You will find those on most espresso machine such as Faema, Cimbali, La Pavoni. Bezzera and Astoria.
