Yes, they can. While stainless steel is LESS SUSCEPTIBLE to corrosion, and is far superior for construction of water and foam extinguishers, that does not take away the possibility of corrosion.

Quality of water supplies used to refill water and foam extinguishers varies greatly throughout North America and the rest of the world. The amount of Chlorine and Chlorides in these water supplies may have an adverse effect on the life of the shell. As little as 30 Parts Per Million (PPM) of Chlorine will cause stainless steel to corrode, but the use of our Model 507 corrosion inhibitor will fix this problem.

Installing stainless steel extinguishers in salt atmosphere environments (around coastal installations) may also corrode the outside of the shell over a period of time. It has been our experience that stainless steel extinguishers left OUTSIDE, UNCOVERED IN COASTAL ENVIRONMENTS DO VERY WELL, since rain is allowed to wash off built up salt. If the same extinguisher is put into an UNVENTILATED CABINET OR HAS A COVER IT CORRODES VERY QUICKLY.

Something else to keep in mind, corrosion on stainless steel shells works completely different and looks different than on mild steel shells, like dry chemical extinguishers. Instead of spreading out in a pattern and then flaking away layers of metal (such as you may have seen on dry chemical extinguishers), corrosion on stainless steel shells will not spread out or flake. Instead it will bore through the shell creating a pinhole at each spot where corrosion has developed a foothold. Anything that looks like aged line corrosion on a stainless steel shell should prompt you to hydrotest the shell (even if it is not due) or in some cases to condemn the unit without a hydrotest.
Amerex is one of the few companies that has been successful in making quality stainless steel water, foam, wet chemical and water mist extinguishers for years. Our vast experience may help you in determining proper inspection, maintenance, recharge and hydrotest procedures for these superior class A, B, C, and K units.

Another little known fact, our model 630 Premix Foam Wheeled Extinguisher is the only foam wheeled unit that uses a painted stainless steel agent cylinder. No interior coatings are necessary and corrosion resistance is superior to any competitive unit on the market - and they are USCG Approved!