1990 Bell & Gossett Heat Exchanger. Model: SU-104-2. S/N: 90779765-0. Nat’l Bd: 18531. Heat transfer flow rate: 50 gpm. Heating surface area: 56 sq. ft. 2-Pass heat exchanger. Shell side: MAWP: 150 psi @ 375 °F, MDMT: -20 °F @ 150 psi. Tube side MAWP: 125 psi @ 375 °F, tube side MDMT: -20 °F @ 125 psi. The “SU” Heat Exchanger is an instantaneous type, designed to heat liquids with steam. No space-wasting, expensive storage tank is needed. Inlets: 1/2 in. dia. NPT (female), 1 in. dia. bevel, 8 bolt 4-1/2 in. dia. flanged port. Outlets: 1 in. dia water port, 2-1/2 in. dia. steam release valve (female), 8 bolt 4-1/2 in. dia. flanged port. Overall dimensions: 73-1/2 in. L x 24 in. W x 81-1/2 in. H. (ACN68a)