Series SVP | Proportioning Solenoid Valve is low cost and uniquely designed. Controls or regulates flow in proportion to a variable voltage input. Compatible with a wide range of gases and liquids.
Amazon.com: Baomain Pneumatic Air Control Solenoid Valve 4V210-08 DC 24V 5 Way 2 Position PT1/4" Internally Piloted Acting Type Single Electrical Control : Industrial & Scientific