Mueller Plate Heat Exchanger. Model: AT20C-20. S/N: 141935. Number of stainless steel plates: 20. Heat transfer surface area: 80 sq. ft. Typical maximum flow: 450 gpm (water). Maximum working pressure: 100 psi. Maximum working temp: 25 °F. Maximum plate pack length: 3.13 in. Minimum plate pack length: 2.88 in. The Accu-Therm is a compact heat exchanger consisting of embossed heat transfer plates with perimeter gaskets to contain pressure and control the flow of each medium. Accu-Therm plates ensure high thermal efficiency, uniform fluid distribution, minimal fouling, and suitability for full differential pressure rating. Inlets: (1) 3-1/2 in. dia. hot, (1) 2-1/2 in. dia. cold. Outlets: (1) 2-1/2 in. dia hot, 2-1/2 in. dia. cold. Overall dimensions: 32 in. L x 18 in. W x 39-1/2 in. H.