Hey everyone, so I had someone give me some Pyro-Chem PCI-50BC extinguishers "7 of them with a handful of other smaller extinguishers"

I've gathered some information as to how they are activated and how they discharge in normal operating setups.
They use a CO2 cartridge to pressurize the valve which opens the tank to expel the dry chem.



I don't have any of the system just the tanks.

I'm wondering if anyone has any info or tips for a safe way to depresurize these tanks to recover the brass and the tank. they are charged to 350 PSI.

Tank
https://imgur.com/4d0j4G2

Regulator
https://imgur.com/W0I5gF1