Regarding Autoclave Performance Qualification

Hello to all,
this is regarding performance qualification of autoclave with the help of data logger / kaye validator, during this activity we use 16 nos. of thermocouples to measure temperature inside autoclave as well as there also temperature sensors of autoclave which shows the temperature in its PLC
so, my querry is what should be the diffrence of temperature between the Thermocouples of data loggers and fixed sensors of autoclave, is there any criteria?

Pritesh.

For comparing between the fixed autoclave sensors and the data obtained using your data acquisition system, you might want to use the sensetivity (+/- ?? C) of the fixed temperature sensors as the comparison factor. If you are seeing significant temperature differences within a certain sample point such as the drain (happened to me once), you might want to make adjustments to how you are performing the sampling at that point to avoid measuring the temperature of the liquid steam condensate.

Dear aschmidt
Querry is like that:
if you binds your outside thermocouple to a fixed sensor of autoclave, then anywhere it may be (in drain or on walls) what should be the diffrence between the temperature measured by both? is it defined anywhere?

another: what should be the diffrence between temperature sensed by the two thermocouples of outside datalogger?

Regards,

Pritesh.
QA-Validations (Ahmedabad.)

Hai Pritesh,

Comming to 1st point of binding external sensor with internal, you have to carefull about coveing of the sensing element of the fixed sensors, please be aware the sensor fitted is normally RTDs so it measure the temp across the area and little higher responce time then Thermocouple, but yes you can justify with a documention stating the deviations, recomended not to tie the sensor with each other.

the deviation of the external two thermocouple are nothing but your relative accuracy limit, no such criteria but should be as low as possible,

hope this is your answer,

Ramesh Sahu

Pritesh, You are doing a OQ, first you would calibrate the autoclave TC’s using a NIST heat well. Once calibrated, then loggers can be placed at various areas of the chamber including one in the drain. Start a cycle and compare autoclave TC’s and logger info. Your Min/Max temperature differences really should not be more than + or - 2C once temp has stabilized. This you could write into your acceptance criteria. Seems a bit arbitrary to just say ‘+ or - 2C’, but that is a normal FAT for autoclaves… so, why not expect that it hold true in your use. Russ

[quote=pritesh]Hello to all,
this is regarding performance qualification of autoclave with the help of data logger / kaye validator, during this activity we use 16 nos. of thermocouples to measure temperature inside autoclave as well as there also temperature sensors of autoclave which shows the temperature in its PLC
so, my querry is what should be the diffrence of temperature between the Thermocouples of data loggers and fixed sensors of autoclave, is there any criteria?

Pritesh.[/quote]

There can be some random errors even after calibration, these can be difference in temperature between the thermocouple cold point sensor and the input terminals and thermal uniformity across the input terminals.
The relevant guideline of HTM2010 states that the repeatability of measurement should be +/–0.25°C or better and that the combined errors of the complete measurement system, including sensors, should not exceed +/–0.5°C. Calibration of the complete measurement system of thermocouples, data logger and computer against a UKAS (or similar) reference thermometer is necessary to reduce systematic and random errors.

Thanx to all for your precious reply,

0.5°C is the allowable diffrnce among the sensors we are inserting in Autoclave for temperature mapping, and i wanted to know abt diffrence in RTD sensors of autoclave and external sensors of validator.

Russ your reply holds exact number i want but can we support it with any reference?

another: is there any criteria for defining the maximum time diffrence for all thermocouples of validators to achieve 121°C?

Thanx and regards

Pritesh.
QA-Validations (Ahmedabad.)

Hi Pritesh,

Answer to your question:another: is there any criteria for defining the maximum time diffrence for all thermocouples of validators to achieve 121°C?

if your chamber is over 800L then its 30 seconds and if the chamber is less than that its 15 seconds. That is 30 seconds after your drain probe has reached your minimum i.e. 120degC.
There is reference to this in HTM2010.

Regards,
Ruth

Thank you, Ruth answer is satisfying.

Pritesh Bhosale.