What type of pump is recommended for collecting low-flow samples from depths greater than 30 feet?

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What type of pump is recommended for collecting low-flow samples from depths greater than 30 feet?

This question is probably based on the fact that a peristaltic pump won’t generally work at depths much beyond about 25-30 feet maximum below ground surface.  My recommendation is for either a portable or a dedicated bladder pump because the bladder pumps work for the widest range of analytes.  It can be used to depths down to 1,000 feet or beyond.  And they have nice flow rate control capability and other advantages, including high reliability.

You can also use an electric submersible pump, this can be either an open- or closed-type design, but it has to have a variable speed motor. There are some 12-volt DC electric submersibles where the manufacturer controls the flow by putting a valve at the surface rather than controlling the motor speed. I wouldn’t recommend this because you are going to get a pressure drop across that well and have the potential for losing volatiles from that sample very readily.

There are a couple other devices like piston pumps, but they are generally used in very deep applications.