More than likely in the commercial world you have needed an expansion tank. Sometimes the requires ASME rated expansion tanks. We at Johnstone can supply you with these. See the flyer below for sizes, but we can get all the from 2 gallons to 1320 gallons. IF you need help with selection, use the submit ticket feature at the top of the page, or use the red tab at the left side of the page. Create a ticket under commercial sales and we will get back with you.