Comparing air compressor potential energy

[sandman_a_c]

So this isn't a typical compare this and that compressor post. I hope it hasn't been covered. I searched but found nothing.

Let's say we have two air compressors:
1. 25 gallon rated at 135psi
2. 20 gallon rated at 155psi

The tank on compressor 2 is smaller, but contains a lot more air pressure. So, if I were to convert compressor 2 to a 135psi, what size tank would it require to maintain the same potential energy? After I have that, I can compare compressor 1 and compressor 2.

 

[sandman_a_c]

Guess I found it. Looks like it is described by Boyle's law. pV=k. Pretty simple math.

So in this case 155 * 20 = 3100. Divide that by the reference psi of 135 and you get 22.96 gallons. So compressor 1 holds more energy.