Solenoid valves v/s slanted seat valves

Dear Leo:

Are you talking about angle valves? URL:

Solenoid valves with orifices larger than 1/16" or so are not direct acting. Therefore, they use fluid pressure to help open the valve, and are therefore not good at preventing reverse flow. Air-operated valves can develop a large seating pressure, preventing flow ("cracking") due to internal process pressure. If I've got air pressure available, I'll pilot one of these valves with a little three-way valve... everytime.

David A. Smith