The word Listed
means that a nationally known, third-party testing laboratory like UL, ULC, CE, FM, etc. has tested
the pipe for use
in Aspiration Systems for Air Sampling. Once the testing laboratory knows that the pipe is going to be adequate for this purpose, they say that it is adequate by Listing
the pipe For Use
with an Air Sampling Aspiration System.
The reason that Listed For Use
is so important is that a PVC pipe of one type might have been tested to be adequate for use in a garden sprinkler system, but that same PVC pipe may be highly inadequate to be used in an air sampling aspiration system. A pipe sold for use in a garden sprinkling system may not be good enough for air sampling for an aspirator.
Also, if you can, check with the technical support people that make the aspirator. If the technical support people aren't available, there's some chance that their website has further information.