Monitoring of
Climate parameters in Cleanrooms
Rooms for critical processes i.e. cleanrooms as well as mini environments demand precise environmental monitoring technology and methods in order to operate consistently within specifications.
This is not just about specifications or norms, but more important about the quality of your products e.g. pharmaceutical medicines or semiconductor chips as well as processes.
Tiny differences in reading might have a huge effect. It is not just the norm deciding, but more important the product need that decides on the accuracy of a measurement. Imagine the loss of the product due to not knowing if you still had an overpressure and such guaranteeing that no contamination could get on or into the product. It might just be 1 Pa or the inaccuracy of the instrument deciding. Imagine product implications due to incorrect humidity or just the doubt if product related requirements have been met. Therefore, it is important to monitor all Cleanroom requirements.
Requirements amongst other things are clean air with high exchange rate, sufficient pressure, exact temperature and humidity regulation at constant air quality. Humidity, temperature and differential pressure can be especially challenging parameters to measure in a cleanroom environment. These environmental measurements must be precise, reliable and carried out with calibrated instruments to ensure the quality of your products and processes. Robust and highly accurate instruments from Novasina address measurement challenges and help with the smooth operation of your cleanroom facilities.
Monitoring of temperature, humidity and pressure
In order to meet specifications, cleanrooms require precise measurements. Keeping cleanrooms conditions constant necessitates accurate and long-term stable instrumentation for the constant measurement and monitoring of temperature, air humidity and differential pressure.
The metrological parameters needed to prove clean room performance are outlined in DIN EN ISO 14644. Continuous monitoring of the temperature, relative humidity and differential pressure helps to ensure product quality as well as document environmental conditions according to the specifications. Depending on the cleanroom use, additional or other relevant specifications might apply.
Temperature and relative humidity testing
Ventilation systems supply a cleanroom with the temperature and humidity levels that meet the requirements for the current application. According to DIN EN ISO 14644 -3, the ability to meet specifications must be tested. Requirements for testing equipment being used for this can be found in DIN EN ISO 7726 Ergonomics of the Thermal Environment, Instruments for Measuring Physical Quantities. This standard states that for relative humidity, the allowable measurement uncertainty is +- 2% RH.
The most common relative humidity measurement method is called the capacitive method, which can meet the uncertainty requirements when acquired from specialised suppliers. However, the electrolytic-resistive sensor provides a more accurate measurement with less interference from chemical components such as H2O2. Novasina’s electrolytic-resistive sensor reaches an uncertainty of +/- 0,5 %RH with the nSens-HT-ENS sensor, making very precise testing possible. With better long-term stability due to a lack of hysteresis and a faster response compared to the capacitive sensors.
Relative humidity is a parameter which is highly influenced by the air temperature. Normally relative humidity and air temperature are measured together, requiring an accurate and specific temperature element. Most capacitive humidity systems measure the air temperature with an integrated, low cost, bandgap temperature sensor, which is not as accurate as a separate PT or the NTC element, using in the Novasina electrolytic humidity measurement system. Find out more about Novasinas nSens sensors here.
