The CUNO 2.5 is the correct reverse osmosis tank for the following:
The 3M Cuno Hydropneumatic Tank for BEV/STM/TSR is a replacement reverse osmosis tank for boiler-based steamer units. This fiberglass water tank features a bladder-style pressure vessel and fittings which are specially designed to accept plumbing from STM and TSR units. This hydropneumatic system boasts a compact footprint that allows access to the tank through a standard doorway while not taking up a large space. This hydropneumatic tank system is 100% sealed, which provides strength and prevents leaks.
3M Cuno Hydropneumatic Tank for BEV/STM/TSR specifications: