The short answer is probably not. The longer answer involves a little math.
If you remember the Ideal Gas Law, PV = nRT
Where P is the pressure in the cylinder, V is the volume of the Cylinder, n is the number of moles of Gas (essentially a count of the number of Gas atoms in the cylinder), R is the Ideal Gas Constant, and T is the temperature in either Kelvin or Rankine. Both of these temperature measuring systems use absolute zero, the temperature at which molecules have no kinetic energy, as a reference.
Tr = Tf+460
so that absolute zero is -460 degrees Fahrenheit. To get temperature in Rankine, you take the temperature in Fahrenheit and add 460.
Tk = Tc+273
or absolute zero is -273 degrees Celsius. To get the temperature in Kelvin, you take the temperature in Celsius and add 273.
Assuming the amount of gas in the cylinder doesn't change (none escapes), and the size/volume of the cylinder doesn't change (only slightly with thermal expansion, but this is still a good assumption), then there is a direct relationship between the pressure in the cylinder and the absolute temperature of the Gas in the cylinder.
P1/T1 = P2/T2 or
P2 = P1 *Tr2/Tr1.
So if you fill a tank to 3000 psi at 80 degrees Fahrenheit and the temperature soars to 120 degrees in your garage, how much does the pressure go up?
P2 = 3000 * (120+460)/(80+460) = 3000*580/540 = 3000*1.074 = 3220 psi.
This pressure is well below the burst disk pressure or the pressure to which the tank is hydro statically tested.
Other things to consider:
The temperature swing will cause a change in pressure inside the tank which will contribute to the fatigue cycling of the tank, however this is much less than the pressure change associated with using the tank, ie breathing it down and refilling it.
Don't over fill the tank. Realize that when the temperature of the tank heats up, the pressure in the tank will also go up so don't try to squeeze in a couple hundred extra psi and then put the tank in the hot garage.
At elevated temperatures rubber components tend to break down faster, ie high pressure hoses. They will still work, just won't last as long.
Hope this helps.
