410A isn't flammable or explosive. As with any tanked gas/liquid, there is a risk of that TANK exploding if it's not handled properly, but that's not limited to 410A.
Here's the info from National Refrigeration's MSDS sheet on 410A:
FLASH POINT:
Gas, not applicable per DOT regulations
FLASH POINT METHOD:
Not applicable
AUTOIGNITION TEMPERATURE:
>750°C
UPPER FLAME LIMIT (volume % in air):
None by ASTM D-56-82
LOWER FLAME LIMIT (volume % in air):
None by ASTM E-681
FLAME PROPAGATION RATE (solids):
Not applicable
OSHA FLAMMABILITY CLASS: Not applicable
http://www.refrigerants.com/MSDS/r410A.pdf