LP Gas Tank at Window

WHat would be the normal required clearance of a LP Gas Tank from a operable window.

Ralph Blinn 018.jpg

try this:

http://disantopropane.com/builders-construction-hvac-propane/asme-tanks.gif

http://disantopropane.com/builders-construction-hvac-propane/dot-tanks.gif

http://www.propane101.com/images/propane-tank-distances.gif