Solinst 404 Inertial Pump

The Solinst 404 Inertial Pump is a hand-operated groundwater sampling pump with no external moving parts, batteries, or compressed gas source. A footvalve — a short stainless-steel or Delrin fitting holding a single check ball — is crimped into the end of a length of tubing and lowered below the water's static level. Jerking the tubing up and down in short, rapid strokes opens and closes the check ball with each stroke, trapping successive slugs of water that stack up the tubing until they discharge at the surface. Because operation relies entirely on hand motion and the tubing itself is inexpensive, the 404 is commonly left in place as a dedicated, single-well pump. Choosing a footvalve size: The Mini (1/4" OD) is sized for narrow CMT multilevel channels and other small-diameter tubing; D16 (5/8", Delrin) and SS16 (5/8", stainless steel) suit standard monitoring wells; SS19 (3/4", stainless steel) and D25 (1", Delrin) handle wider casings and deeper, higher-volume purging where a larger footvalve improves lift.