Bladder Expansion Tanks Product Highlights Sizes from 1 gallon to 150 gallons Protects antifreeze sprinkler systems from damaging effects of thermal expansion Industrial quality designs Underwriters Laboratories (UL) listed and manufactured in accordance with the ASME code Section VIII, Div.1 All sizes in stock for fast, on-time deliveries 175 psi design pressure with a 4X safety factor Full inventory for immediate shipment Young Engineering UL approved expansion tanks are designed specifically for the fire protection industry to protect anti-freeze sprinkler systems from the damaging effects of thermal expansion. On systems that utilize backflow preventors, over-pressure problems can occur when temperature variation (excessive heat) causes the antifreeze to expand resulting in component damage. This over-pressurization can be alleviated with Young Engineering industrial-quality expansion tanks which "absorb" the expanding fluid, thereby controlling the pressure to a safe level. The National Fire Protection Association (NFPA 13) requires the use of expansion chambers in antifreeze systems which use backflow preventors. Expansion Chamber Article (pdf file for download) Sizing Chart (pdf file for download) BET Manufacturer Representatives