Khairul_jaafar
Registered
Dear Elsmar Community,
I hope this message finds you well. Our testing laboratory is currently preparing to comply with ASTM E145 requirements, and we are seeking guidance regarding the assessment of our ovens. Our laboratory specializes in testing, and we currently lack experience in calibration. Additionally, we've found that no calibration labs in our country are accredited to ASTM E145, and they are not familiar with time-constant tests. Therefore, we plan to verify our oven by ourselves. Your insights on our specific issue would be greatly appreciated.
Background:
The specific procedure we're following is outlined in ASTM E145, involving heating the oven to within 10 °C of its maximum operating temperature (our oven's max capability is 200 °C), stabilizing it for at least 1 hour, and then opening the door for 1 minute. During this time, a standard specimen and a differential thermocouple are suspended in the oven. After closing the door, the procedure instructs us to record or measure the temperature differential every 10 seconds and determine the time in seconds required for the temperature difference to decrease to one-tenth of the original or maximum value.
Questions:
1. Closed Oven Scenario:
After opening the oven door for 1 minute and considering the current set temperature of 200°C, I am unclear on how the temperature is expected to decrease to one-tenth of the original value once the oven is closed. Could someone provide clarification on how this should be interpreted and the practical steps to achieve this?
2. Calculating Time Constant:
As ASTM E145 does not provide a specific formula for calculating the time constant, the procedure suggests determining the time in seconds required for the temperature difference to decrease to one-tenth of the original or maximum value and considering this as the time constant of the oven. Can someone provide guidance on the calculation method for this?
I appreciate any insights, experiences, or advice you can share regarding the interpretation and execution of the time constant test as per ASTM E145. Your practical knowledge will be invaluable to me in conducting this test effectively.
Thank you in advance for your time and assistance.
I hope this message finds you well. Our testing laboratory is currently preparing to comply with ASTM E145 requirements, and we are seeking guidance regarding the assessment of our ovens. Our laboratory specializes in testing, and we currently lack experience in calibration. Additionally, we've found that no calibration labs in our country are accredited to ASTM E145, and they are not familiar with time-constant tests. Therefore, we plan to verify our oven by ourselves. Your insights on our specific issue would be greatly appreciated.
Background:
The specific procedure we're following is outlined in ASTM E145, involving heating the oven to within 10 °C of its maximum operating temperature (our oven's max capability is 200 °C), stabilizing it for at least 1 hour, and then opening the door for 1 minute. During this time, a standard specimen and a differential thermocouple are suspended in the oven. After closing the door, the procedure instructs us to record or measure the temperature differential every 10 seconds and determine the time in seconds required for the temperature difference to decrease to one-tenth of the original or maximum value.
Questions:
1. Closed Oven Scenario:
After opening the oven door for 1 minute and considering the current set temperature of 200°C, I am unclear on how the temperature is expected to decrease to one-tenth of the original value once the oven is closed. Could someone provide clarification on how this should be interpreted and the practical steps to achieve this?
2. Calculating Time Constant:
As ASTM E145 does not provide a specific formula for calculating the time constant, the procedure suggests determining the time in seconds required for the temperature difference to decrease to one-tenth of the original or maximum value and considering this as the time constant of the oven. Can someone provide guidance on the calculation method for this?
I appreciate any insights, experiences, or advice you can share regarding the interpretation and execution of the time constant test as per ASTM E145. Your practical knowledge will be invaluable to me in conducting this test effectively.
Thank you in advance for your time and assistance.
