The results of an experimental study and numerical simulations of resin bonded sand/airflow in a square corebox with an H-shape insertion and passage between upper and lower pockets of the pattern are presented. A computer-controlled electronic system was designed and built to measure dynamic pressures and flow rates inside the corebox during mold filling, gassing and purging cycles of Phenolic Urethane Amine (PUA) process. Contour maps of the pressure distributions inside the corebox were created based on barometric measurements. A good agreement between experimental results and numerical simulations was found. (C) 2003 Elsevier Science B.V. All rights reserved.