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Thread: FH calculation

  1. #1

    Lightbulb FH calculation

    Dear All

    While performing Tunnel validation using z value of 46.4 and achieving exposure time of minimum 3 min during sterilization at temperature of 300 deg and more. Does this meet the acceptance criteria for depyrogenation & sterilization. I also want to know that what shud be the FH value, is it 3 min. or 30 min at 300 deg and Z= 46.4. Please help to clear my confusion
    Annie

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  3. #2
    Validation Analyst
    Join Date
    Aug 2008
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    UKRAINE, Kiev
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    See attached file in the post http://www.askaboutvalidation.com/fo...ead.php?t=1299
    This document describing 3 types of F-value.
    F0-for saturated steam sterilization
    FH-for dry heat sterilization
    Fd-for dry heat depyrogenation
    General different between FH and Fd is Z value. For FH=20, for Fd=46,4
    Also calculating standart process temperatures for FH=170C, for Fd=250.
    Acceptance criteria for FH and Fd=30 equivalent miutes.

  4. #3

    Default

    Dear
    if we are giving temperature of > 300 degrees instead of 250 deg than also the FH value remain same i. e 30 min?
    As far as i think when we are increasing the temperature from 250 to 300 deg (high temp), sterilization time should decrease
    Annie

  5. #4
    Validation Analyst
    Join Date
    Aug 2008
    Location
    UKRAINE, Kiev
    Posts
    14

    Default

    Maybe, you mix-up real process time with equivalent time? Also, FH-value correct for temperature range 160-200 C, because z-value=20 min correct for range 170-190 C.
    Follow link
    http://www.penntech-corp.com/Washing...ng-Depyro.html

  6. #5

    Default FH calculation

    Quote Originally Posted by annie View Post
    Dear All

    While performing Tunnel validation using z value of 46.4 and achieving exposure time of minimum 3 min during sterilization at temperature of 300 deg and more. Does this meet the acceptance criteria for depyrogenation & sterilization. I also want to know that what shud be the FH value, is it 3 min. or 30 min at 300 deg and Z= 46.4. Please help to clear my confusion
    Dear Annie,
    For the calculation of depyrogenation lethality it is necessary to reach the temperature of chamber above 250 degrees.
    Z value is 46.4 for 250 degrees so when ever you calculate the FH value it means the exposure of load at 250 degrees for the outcome time period.
    Lethality calculations are done during the start and end of movement in depyrogenation zone of tunnel.But when you start the validator it starts the calculation from the start point so you cannot be sure about the lethality and endotoxin reduction for this performance of endotoxin challenge is required with 10000EU and min. 3 log reductions is required.

  7. #6

    Default

    Quote Originally Posted by annie View Post
    Dear All

    While performing Tunnel validation using z value of 46.4 and achieving exposure time of minimum 3 min during sterilization at temperature of 300 deg and more. Does this meet the acceptance criteria for depyrogenation & sterilization. I also want to know that what shud be the FH value, is it 3 min. or 30 min at 300 deg and Z= 46.4. Please help to clear my confusion
    As you calculate Fo values with base temperature 121oC and z=10oC on the same way you calculate Fh values but your base temperature is not 300oC, it is 250oC and z=46.4oC. It seems that your tunnel set temperature is 300oC. In this case, you let thermocouples go trough tunnel and calculate lethality. Fh/Fo is cumulative value and it grow with temperature. So, for tunnel Fh will start to raise at approx. 200oC and have a maximum in the sterilization/depyrogenation zone (highest rate). For entire cycle Fh should be above 30 minutes.
    Zeljko Joksimovic

    Independent Expert Associate for Equipment Qualification

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