There are numerous configurations of both the 3M Versaflo series and the Sundstrom respirators so you would need to know what specific configurations of each to compare. The SR500 is only the part worn on the waist that contains the fan, filters, and battery. You might want to consider the SR700 instead which is for particles only and probably costs less although the SR700 has lower air flow. There are numerous options for the headgear and the SR540 headgear is somewhat comparable to the Versaflo units except that it is not a full helmet and lacks side protection unlike the Versaflo that I have.
The SR500 blower has two speeds ... Standard delivers up to 6.2 CFM and Maximum delivers up to 8.5 CFM. My Versaflo helmet is being used with a BreatheEasy turbo unit and when used together is rated at a minimum of 10 CFM. The BreatheEasy turbo unit is bulky compared to other options, but it can be used with a number of different filters whereas the Versaflo blower unit is for HEPA particulate filters only.
The Australian certification standards are different from US standards so it would be impossible to say how the impact and filtration test results line up against each other, but I assume they are reasonably close.
I was able to put my system together for a fraction of the retail price by perusing eBay and everything was new. Here is a long thread about the
Versaflo M-407 and the BreatheEasy turbo unit that would be worth reading if you are thinking about the Versaflo. The only reason that I bought the M-407 was the great price ... otherwise the M-200 series or M-300 series would be my choice.
