A 52 gallon tank and a air pressure of 4,350 psi is scary.

I don't think you going to get air at gas stations which is 4350 psi I would be surprised if you could air at 1/10th of this pressure [+400 psi] from any gas station.

Here is interesting quote regarding diving tanks:
"Next there are medium or standard working pressures that most aluminum and some steel tanks are rated to (3000psi or 204bar). Nearly every compressor in the country can pump to this pressure easily. Finally we have high-pressure tanks which can be as high as 3500psi. The problem with high-pressure tanks (usually steel) is that they heat up very fast during filling and stay hot. This makes filling difficult and sometimes riskyin fact many shops and charters boats can't fill past 3000psi (204bar)."
http://www.sportextreme.com/se_shop/htc/diving/Tanks/Tanks.page.index.html

So compressed air at gas stations are used to to fill up tires which might need as much 40-60 psi for truck tires. This stuff is usually rated around 150 psi [normal maximum use- though they could probably handle as much as 200 to 300 psi- but this normal equipment can't handle, say +1000 psi.