Inert Proportional Valves

Proportional MiDP Models Are Ready For Difficult Liquids and Gas.

Humphrey Products has designed the new MiDP Series Proportional Valves (S390 and S391) to precisely control the flow of a wide range of aggressive liquids and gases.

The MiDP Series features Humphrey’s new stepper motor operator that allows for precise positioning and flow control, with outstanding repeatability and low hysteresis. The flexing diaphragm poppet design safely isolates the stepper motor from media penetration, while the inert Radel™ body material ensures long life and sustained performance.

The wetted flow path is Humphrey’s 350 Series diaphragm separated design, which has more than 20 years of proven reliability in medical industry applications such as kidney dialysis equipment and endoscope reprocessing.

Available with variety of diaphragm elastomer options, including FFKM, EDPM and Viton™GF, the MiDP Series Proportional Valves is suitable for a multitude of applications requiring broad chemical and temperature compatibility.


MiDP Proportional Valves

MiDP S390 & S391 0 – 8.5 SLPM Water /
0 – 325 SLPM Air @ 60 PSI
2.6 MAX Watts 0 – 60 (0 – 4.1)

For more information on the MiDP S390 and S391 Series, visit the Online Catalog or download the iDP 390/391 brochure.

Humphrey offers application assistance throughout this process to ensure you achieve the best results. Call 844-447-9009 or email