Solinst Model 408M Micro Double Valve Pump

Solinst Model 408M Micro Double Valve Pump


The Solinst model 408M micro double valve pump has a remarkably small and flexible design. The pump includes PTFE tubing and manifold.


  • Only 3/8" (10mm) in diameter, ideal for narrow applications
  • Flexible Teflon, goes almost anywhere
  • Inexpensive and readily dedicated
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The Solinst Model 408M Micro Double Valve Pump (Micro DVP) has a remarkably small and flexible design. It is a pneumatic pump similar to a Bladder Pump, but using coaxial Teflon tubing, rather than a Teflon bladder to give high quality samples. It is small enough to fit in 1/2" (13 mm) tubing and all channels of the Solinst Model 403 CMT Systems, as its diameter is only 3/8" (10mm). The unique combination of flexibility and size make the pump easy to transport and install in a variety of applications.

The Micro DVP is ideal for low flow sampling and narrow down-hole applications. Flow rates of 20 to 150ml/min, are obtained, with very small associated purge volumes from within the narrow applications. The Micro DVP is durable and easy to operate using the pre-sets and fine tubing capabilities built into the Solinst Model 466 Electronic Control Unit.

The Micro DVP uses coaxial Teflon tubing in lengths of 50', 100', 150', and 200' (15m, 30m, 50m, and60 m). The 50 ft. (15 m) pump is also available with LDPE outer drive tube and a Teflon inner tube. The pump body and filter is 6 x 3/8" (150x10mm). It is constructed of coaxial Teflon tubing with stainless steel fittings and a 100 mesh stainless steel filter. Filters are easily cleaned and replaced. A manifold at the top end of the pump has a 3/16" (5mm) Teflon sample tube and a quick-connect fitting for easy attachment to the Control Unit. A multi-purge sampling head is also available for use with the CMT System.

Formation water enters through the filter under hydrostatic pressure into both the inner Teflon tube and the annulus of the coaxial tubes. Drive gas/air is cycled down the annular space between the two tubes to close the lower check valve and push the water up the inner sample tube. The pump is then vented to allow new formation water to enter both tubes under hydrostatic pressure. Air/gas pressures are carefully controlled at all times to ensure that the air/water interface never enters the body of the pump. Repeating the pressure/vent cycle brings the high quality sample to the surface at a controlled rate. The Micro DVP operates with 2ft (0.6m) or more head of water above the intake.

Applications include groundwater sampling in:
  • CMT and Waterloo Multilevel Systems
  • Direct-Push/Drive-Points
  • Low flow monitoring in narrow diameters
What's Included:
  • (1) Solinst Model 408M Micro Double Valve Pump
  • (90) feet PTFE tubing
  • (1) Manifold
Image Part # Product Description Price Stock Order
Solinst Model 408M Micro Double Valve Pump 108220 Model 408M micro double valve pump, 90ft PTFE tubing, and manifold
Usually ships in 1-2 weeks
Solinst Model 408M Micro Double Valve Pump 108219 Model 408M micro double valve pump, 140ft PTFE tubing, and manifold
Usually ships in 1-2 weeks
Solinst Model 408M Micro Double Valve Pump 108218 Model 408M micro double valve pump, 240ft PTFE tubing, and manifold
Usually ships in 1-2 weeks
Image Part # Product Description Price Stock Order
Solinst 12 Volt Air Compressor 106009 12 volt oil-less air compressor, includes battery clips
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Solinst Model 408M Micro Double Valve Pump Reviews

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Mixed feelings about this equipment
I have mixed feelings about this piece of equipment. If your budget is limited and your sample volumes are low, I would say that this gizmo might be a decent fit for your job. But if you have a huge bottle set in which you are sampling for every analyte under the sun, then forget it. You are probably better off drilling multiple wells and hand bailing or using a dedicated bladder pump or some other sampling method; because this aparatus is time intensive.

We were tryng to use Solinst's system for a characterization study. We were trying to use a single, non-dedicated pump, decon'ed between multiple wells. Here are the things that caused us problems:

1) the amount of water you can pump per cycle is limited by the standing water in the tubing, the minimum for which is something like 10 feet, just for the pump to function. Our analyte list , which included both radionuclides and SVOAs required us to sample two or three gallons, which took forever at a little squirt per cycle. We were lucky to get more than two samples done per day.

2) dirty wells with a lot of sediment caused the tiny valves in the pump to not seat properly, so water would flow back down the tubing. This was problematic both from a standpoint of getting water out of the well and trying to monitor water quality parameters in a flow through cell for low flow sampling. Forget the latter. Shaking the tubing sharply up and down sometimes alleviated this , but you had to be careful not to kink the tubing and always be vigilant on the state of the water level in the tube.

3) They may have changed the design since a year and a half ago, but the manifold where the air goes in and the water comes out was made of plastic parts that became stripped easily and either leaked or popped apart when pressurized.

4) You have to be careful not to overextend the pressurization part of the pump cycle, otherwise you will pump the tubing dry and introduce air into the sample. If you are trying to monitor water quality parameters for low flow sampling, this will mess you up.

So. Some advantages, many caveats.

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