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Blasting Operations of Summit Brick <br />ols for Blast Noise, 2.3 cony <br />r blast Limits (RI 895, 1980) <br />]surfing System- Maximum Level <br /> Flat Response 134 Peak <br /> Flat Response 13- Peak <br /> Flat Response 129 Peak <br /> Slow Response 105 Peak <br />mended Blasting Air Overpressure Limits <br />2.3.2 Air Overpressure Limitations: <br />The regulatory limit defined by USBM, and promulgated by Colorado State Department <br />of Labor Regulations, for airblast measured with 2-Hz response seismographs is 133 dB-L. <br />As indicated in Figure 2.6 ,damage to old or poorly glazed windows does not occur until <br />overpressure reaches about 150 dB-L. More importantly, since the decibel scale is a <br />logarithmic ratio, the actual overpressure at 150 dB-L is 0.092 psi, versus 0.013 psi at 133 <br />dB-L. Therefore, the actual pressure at the 133-dB-L limit, is over seven times <br />(0.092/0.013) lower than the threshold damage level at 150-dB-L. The relationships <br />between actual overpressure expressed in psi and decibel scale measurements are shown in <br />the following forms of Equation 3. 1. <br />dB=20Loglo(P/Po) or P=10(dB/20) x Po ~F.~uation 3.1) <br />Where: dB = decibels, P overpressure (psi), P, =Reference Pressure (2.9 x ]0-9 psi) <br />Review of Blasting Operations of Summit Brick <br />21 <br />