The Solinst 407 Mk2 Bladder Pump is a pneumatically-driven groundwater sampling pump built around a flexible Santoprene bladder inside a rigid stainless-steel or PVC body. Compressed air or nitrogen from a surface control unit pressurizes the space between the bladder and the housing, collapsing the bladder and forcing the water inside it up through a check valve to the discharge line; venting the drive pressure lets the bladder re-expand and refill with fresh formation water through a second check valve. Because the drive gas only contacts the outside of the bladder — never the sample itself — the pump avoids aerating or degassing the water, making it a standard choice for VOC-sensitive, low-flow sampling under EPA protocols.

Do you have everything you need? The 407 Bladder Pump requires a separate compressed-gas source and control unit — such as Solinst's 464 Electronic Pump Control Unit and a 12V compressor or gas cylinder — to drive the bladder cycle; it does not operate on its own. Stainless-steel models are rated to 500 ft (150 m) below grade; PVC models to 100 ft (30 m). Replacement bladders, drop tubes, tubing, and compressors are available on the Solinst 407 Bladder Pump Parts & Accessories page.