Get current pricing for Mueller, 940 Sq. Ft. Mueller 940.4 Sq. Ft. Mueller 304 Stainless Steel Accu-therm Plate Heat Exchanger, Model At40 Frame Type B-20. Rated 75 Psi @ 150 Deg F. 192 Plates - 0.5 . Product Category: Process Equipment, Sub Category: Process Heat Exchangers: