Experimental investigations of validation processes in clean rooms

Clean rooms are practically ventilated with the high air change rates per hour continuously to keep the particle contamination in the amount appropriated to the ISO class for which it was designed in order to provide the intended process. This means serious operating and maintenance costs. With this study, it was aimed to examine the cleanroom validation and operation steps, to determine the HEPA filter replacement interval and parameters in the laminar flow units for operating theaters, and to reduce the air change rate per hour in a way to protect the pressure difference, except when the cleanroom is not used. In the study, before the replacement of the HEPA filters of 23 operating rooms in Gazi University Hospital, the measurement of air change rate was made with the help of an anemometer and compared with the data of the last two years. After that, particles were counted with particle counter to validate the ISO Class of the cleanrooms. The air change rates before the filter change of 23 operating rooms it was measured under 20 ACH in one operating room, while it was higher than the first measurement in five operating rooms. All of the operating rooms preserved ISO classes after filter replacement. It was concluded that HEPA filters often get dirty and prevent air transition over time, but some filters allow more air transition as a result of small openings or ruptures. Therefore, HEPA filter replacement is considered as the main criterion in practice as an excessive pressure loss in the filter, but the possibility of leakage in the filter or casing should also be evaluated. As the airflow rate is reduced except operating hours, also it could be called as night mode, determination of the decontamination time, which is one of the steps of validation must be evaluated. It is calculated to possible to save up to 63,2% in energy consumption. Also it has been calculated that only by acquiring the night mode qualification in the operating rooms in public hospitals in Turkey, approximately 40 000 000 TL can be saved in operating costs and more than 8,000 tons of greenhouse gas emissions can be prevented It is also clear that this will make a positive contribution to the life of HEPA filters and the maintenance costs of the facility.