1991 Mueller Plate Heat Exchanger. Model AT20-C-20. S/N: 101036-6. Nat'l Bd: 18946. Number of stainless steel plates: 68. Heating surface area: approx. 242.49 sq. ft. Nominal max. flow rate: 450 gph (H20). MAWP @ 150 °F: 100 psi. MDMT @ 100 psi: 32 °F. Plate pack dimensions: 8.80 in. (max), 8.51 in. (min). Inlets: (1) 3-1/2 in. dia. (cold inlet), (1) 3 in. dia. (hot inlet). Outlets: (1) 3-1/2 in. dia. (cold out), (1) 3 in. dia. (hot outlet). Overall dimensions: 25 in. L x 17 in. W x 35 in. H.