MEASURED AND CALCULATED PRESSURES AND PRESSURE DIFFERENCES OF TINPLATE CANS UNDER STERILIZATION CONDITIONS

The authors measured the inside and outside pressures of tinplate cans (V-0 = 3230 cm(3)) in three experimental runs, simulating sterilizati on processes with water filled cans. A method for the calculation of i nside pressure was also created, using finite differences and stepping with 10(-4) bar pressure difference (inside minus outside pressure) i ncrement. The calculation method includes the volume change vs. pressu re difference relation based on previous laboratory measurements (KORM ENDY et al., 1994). The mean difference between measured and calculate d inside pressures varied between 0.048 to 0.073 bar. The mean relativ e difference as related to the measured inside pressure varied between 2.37 to 8.02%. Calculated inside pressures fairly followed measured v alues. However, the mean relative difference as related to the differe nce of inside and outside pressures reached higher values.