Yes, removing and filling the tank is that easy. But not so fast.
The CNG tank is identical to that of a scuba tank with the exception of the threads in the tank due to a different valve assembly.
Any tank that holds compressed gas must be hydrostatic tested every 5 years or prior to refill if longer than 5 years.
These tanks hold gas at pressures of 2,250 psi. That equals about 80 cubic feet if gas in volume.
Check the top of the tank near the neck. The stamping on the tank should show the month and year of the last test.
I have a '85 S2, 9.2C. My CNG tank still has 550 psi in it. The stamping is the original stamping from the factory. My tank will need a visual and hydrostatic test prior to being filled again.
Check with your local scuba dive shop for a hydro test. It should only cost $20 or $30 bucks.
If it passes both tests, you're good to go on a refill. If not, your tank is junk scrap metal and must be replaced.
The good news is, very infrequently does a steel tank fail a hydro test.
Usually when that happens, the tank is extremely old and has been exposed to the elements for a long time.
Replacement of the tank is difficult in that "CNG" tanks are not easy to locate.
Your CNG fill station and dive shop can help you with testing, filling and replacing the tank if necessary.
Good luck.
Pat
Oinkers Aweigh
'85 S2 9.2C
Bay City, MI