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MSR Guardian Purifier
Posted: Wed Aug 12, 2015 3:47 pm
by johnhens
MSR is coming out with a reworked version of its Miniworks, the Guardian. The engineered filter will remove viruses and still pump 2.5 liters per minute (their claim). It will run in the $300 range. It will be available in 2016.
http://guardianpurifier.com/
Re: MSR Guardian Purifier
Posted: Wed Aug 12, 2015 9:35 pm
by Midwest Ed
That's quite an improvement in filtration size but I noticed they don't actually specify the size of the new filter (at least I couldn't find it). I looked up the sizes of the 3 viruses listed (Norovirus / Norwalk, Rotavirus & Hepatitis A virus) and the minimum size of these is in the range of 0.020 to 0.025 microns. According to the
CDC a minimum filter dimension needed for these virus is 0.01 micron (although the CDC spec for this nanofiltration is inconsistent.) For reference the NPS specifies a 0.4 micron filter to remove the native tapeworm egg which has a size of 10 to 20 times larger than the filter. Most popular backpacking filters today have dimension specs (pore size) of 0.1 to 0.2 microns.
The main point I'm making is that there are viruses much smaller than those 3 listed but then the next question is how many of them are actually prevalent in potential drinking water, especially in a wilderness setting. But MSR does not claim to remove all viruses, just those 3 listed.
