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.
- No moving external parts, batteries, or compressor — powered entirely by hand motion
- Single stainless-steel check ball seals between strokes to lift water in successive slugs
- Available in five footvalve sizes from 1/4" mini to 1" diameter
- Compatible with low-cost LDPE, HDPE, or PTFE tubing
- Inexpensive enough to dedicate permanently to a single well, eliminating cross-contamination risk
- Effective in silty or turbid water where other pump types can clog
- Shallow groundwater sampling and well purging
- Sampling inside narrow CMT and Waterloo multilevel monitoring channels
- Dedicated single-well sampling installations
- Low-budget or high-volume sampling programs
- Direct-push and small-diameter monitoring wells
- Field conditions where sediment-laden water fouls other pump types