5.1 Frequency:
5.1.1 The test shall be carried out In-house with calibrated instruments or approved external agency initially at the time of validation.
5.2 Instrument to be used:
5.2.1 Suitable pneumatic or thermal aerosol generator to provide appropriate challenge aerosol concentration in the appropriate size range.
5.2.2 Suitable test aerosol (PAO).
5.2.3 A discrete – particle counter having a minimum sampling flow rate of 28.3 L/M.
5.3 Acceptance criteria:
5.3.1 The recovery time for clean room to regain specified cleanliness class level should be within 15 minutes.
5.4 Pretest conditions:
5.4.1 Prior to testing, airflow velocity and pressure difference between the clean rooms should be established as per the specified requirement.
5.5 Test Procedure:
5.5.1 Set up the particle counter in the clean room where the recovery time has to be determined. Particle counter should not be placed directly under the air outlet Adjust the single sample volume, number of cycles and delay time of the counter and it should be adjusted to not more than 10 seconds.
5.5.2 Adjust the single sample volume to the same value used for determining the cleanliness class. In the case two different particle sizes are used for the cleanliness classification, the smaller one should be chosen.
5.5.3 Place the particle counter probe at the Test point and the probe should not be placed directly under the air outlet.
5.5.4 First, check and record the actual particle count level in the clean room, generate the smoke using the Aerosol generator at the air inlet to the room in such a way that the generated smoke distributed uniformly, until the particle count level in the room becomes approximately 100 times (Worst case) the largest cleanliness level.
5.5.5 Start measuring & recording the particle count each minute. particle count level gradually comes down.
5.5.6 The particle counts readings to be taken until the cleanliness level in the room is restored to the original condition recorded & record the recovery time.
5.5.7 Cleanliness recovery rate is obtained from the slope value of the line.
5.5.8 Test report should have the following details:
5.5.9 Identification of apparatus operator and data collection facility.
5.5.10 Identification of apparatus, its calibration status and the test aerosol used.
5.5.11 Occupancy states
5.5.12 Measured point location & cleanliness class recovered time.
5.5.13 Area cleanliness classification.
5.5.14 Maintain the area recovery test certificate in respective qualification document.