What does it mean when charge data is normalized?
All manufacturers furnish charge performance data from the results of QC or API tests. Testing is done by shooting shaped charges into concrete targets with a compression strength specific to the target. It has long been known that the compression strength of the concrete directly effects the TTP value of the charge. Normalization. is a mathematical attempt to present an apples to apples comparison using equivalent concrete strengths. Industry standards use a 3.8% increase (as referenced by SPE paper #27424) in penetration per 1000 psi above 5000 psi concrete. For example: a test charge yields a value of 28.5″ in 6000 psi concrete target. To normalize this charge to a 5000 psi concrete target you would use the following calculation… TTPN = TTP + (TTPx3.8%) x (TPSI-5000)/1000. Where TTPN would be the normalized value in inches. TTP would be the original through target penetration value. TPSI would be the compression strength of the target material.
