D Value Calculation Sterilization

Example of post calculation of f 0 17 1 7.

D value calculation sterilization. D u lhsk log 10 n 0 0 2507 where. The sterilization process is generally carried out in a pressurized chamber designed similarly to a steam autoclave but with the additional features. Symbols and definitions used in sterilization technology 18. It shows that only 2 73 log reduction is required to decrease the microbial population from 540 to 1.

The information obtained above is then converted into base 10 logarithms in order to calculate the d value by using the following equation. The d value is the time in minutes required to reduce the microbial population by 90 or 1 log cycle i e to a surviving fraction of 1 10. Total log reduction required for sterilization of the material with sal value of 10 6 2 73 6 8 73. Sterilization process will need to achieve an 8 log reduction in viable organisms this will require 8 times the d value e g.

For d value certification it is important that the same test method be used for d value verification. Temperature or set of conditions to achieve a log reduction that is to kill 90 or 1 log of relevant microorganisms. F 0 or equivalent exposure time at 121 c 11 1 5. F0 value of a saturated steam sterilization process is the lethality expressed in terms of equivalent time in minutes at a temperature of 121ºc delivered by the process to the product in its final container with reference to microorganisms possessing a z value of 10.

D value or decimal decay time 7 1 2. In microbiology in the context of a sterilization procedure the d value or decimal reduction time or decimal reduction dose is the time or dose required at a given condition e g. You must keep in mind that the total heating time has to have the exact same units as the d value when performing your calculation. A d value is denoted with the capital letter d.

The d value decimal reduction time is the time in minutes that is needed to reduce a population of a particular microorganism by one log level at a given temperature. Essentials of moist heat sterilization kinetics 5 1 1. Lethal rates 14 1 6. Total sterilization time at 121 c with d value of 2 5 min log shall be 2 5x8 73 21 82 minutes.

Level 2 script of the wfhss education group sterilization of medical devices page 6 35 2 1 1 d value d value. Z value or temperature coefficient 9 1 4. If the d value is given to you. D d value minutes log reduction.

If the organism has a d value of 2 minutes then 8 x 2 16 minutes will be required to achieve an 8 log reduction and an sal of 10 6 point z. N 0 average population of the biological indicator spores carrier. Sterility as probable effect of exposure time 7 1 3.