Power sprayers tanks are usually made of polyethylene (aka poly, or plastic), fiberglass or stainless steel.
Today I am going to discuss stainless steel tanks.
Stainless steel tanks are clearly the most durable, and should last much longer than any other material. That's the good news.
This longevity has a cost. These tanks are clearly the most expensive. They are also heavy. The thickness or gauge of steel should be selected based on the size of the tank, the types of roads being driven, etc. The larger the load and rougher the ride, the thicker (and more expensive) the steel.
Stainless tanks can be built with a baffle (to reduce water sloshing), and can be split into two or more tanks so you can carry more than one spray product.
I view stainless tanks as more difficult to modify. If a customer wants to change plumbing on a poly or fiberglass tank, we can add fittings, add agitation, etc. With a stainless tank, it takes more specialized equipment to cut or weld the tank.
In my opinion, steel tanks are overkill for most pest and weed control applications. One final note, if you are determined to buy a steel tank, don't settle for anything but stainless steel or you are asking for problems, such as rust.