HVAC validation

Rahul Kashyap

Qualification Plan & Methodology:

  • Following test parameter shall be performed during performance qualification
  • Test Parameter
  • Velocity and air changes
  • Integrity test for HEPA filter
  • Non-viable particulate count
  • Recovery test
  • Air flow pattern
  • Temperature and relative humidity of the area
  • Pressure differential
  • Power Failure study
  • Viable count (microbial monitoring)

 Performance Qualification Procedure:

Air Velocity and Air Changes:
  • The air velocity and air changes test shall be performed by qualified and trained person only.
  • Measuring instrument being used shall be calibrated with reference to NPL/NABL traceable reference standard.
  • Ensure that the air handling unit shall start at least 30 minute prior to start the air velocity test.
  • Air velocity should be measured at downstream of each final filter and supply diffuser or grill should be removed before the measurement.
  • Measure the air velocity with calibrated anemometer by selecting anemometer in feet per minute.
  • Number of calculated measuring point is less than 4 so we are decided minimum measuring location are 5 including centre and air velocity must be taken as per below diagram.

V1                                                                         V2
V4                                                                        V5

To measuring the filter face velocity/checking of uniformity, the distance of anemometer probe form filter face area should be about 150 mm to 300 mm.
Measuring time at each position should be at least 10 seconds duration and after that value should be recorded.
Note down readings and calculate the average velocity and multiply by the grill area in sq. ft. After getting average CFM across the grills/diffusers, add all CFM in that particular cubicle.
Method of calculation of air change per hour as follow;
Average velocity (A)
(V1   +    V2    +    V3     +   V4    +     V5)
Total air flow (CFM) = V x B; Where,
A                               Average velocity
V                              Velocity
B                              Filter face area
CFM            Cubic feet/minute
After getting total CFM delivered to the cubicle and volume of that particular cubicle, calculate the air changes per hour as per below formula;
Air changes per hour
Total (CFM) of the room
x   60
Volume of the room in ft3
Note down air changes for each room of that area of in test certificate.
Acceptance criteria: The air changes per hours should NLT 20 ACPH

HEPA Filter Integrity test:

  • The filter integrity test shall be performed by qualified and trained person only.
  • Measuring and testing instrument being used shall be calibrated with reference to NPL/NABL traceable reference standard.
  • Filter integrity testing shall be performed after operational velocities have been verified and adjusted where necessary.
  • Poly alpha olefin (PAO) shall be used for the generation of particles/ fumes. (Ref: ISO 14644) MSDS of the same shall be provided by the external agency.
  • Position the aerosol generator such that aerosol is produced into the upstream of the subjected HEPA filter.
  • Provide compressed air to the fume generator at pressure of 1.5-2 kg/cm2.
  • The concentration of the aerosol challenge upstream of the filter should be between 20 mg/m³ and 80 mg/m³.
  • A concentration lower than 20 mg/m³ can reduce the sensitivity of leak detection. A concentration greater than 80 mg/m³ can give rise to excessive filter fouling over the extended test period.
  • Scan the upstream concentration and set photometer 100%.
  • Scanning should be performed over the entire downstream face of each filter, the perimeter of each filter, the seal between the filter frame and the grid structure, including its joints at the distance of approximately 3 cm from the downstream filter face or the frame structure.
  • The probe traverse scan rate when using 3 cm x 3 cm square probe should not exceed 5 cm/s with a rectangular probe, the maximum area scan rate should not exceed 15cm²/s.
  • While scanning, any indication of leak equal to or greater than the limit which characterizes a designated leak should be cause for holding the probe at the leak location. The location of the leak should be identified by the position of the probe that sustains the maximum reading on the photometer.
  •  Measurement of the aerosol upstream of the filters should be repeated at reasonable time intervals between and after scanning for leaks, to confirm the stability of the challenge aerosol concentration.
  • Acceptance Criteria: The penetration of the HEPA filter should not be more than rated efficiency of the filter i.e. 0.01%. (ISO 14644 & WHO TRS 961)

Particle count:
  • The particle count test shall be performed by qualified and trained person only.
  • Measuring instrument being used shall be calibrated with reference to NPL/NABL traceable reference standard.
  • Ensure that the sampling locations are evenly distributed throughout the area of the clean room.
  • The volume sampled at each location shall be at least 2 litres, with a minimum sampling time at each location of 1 minute. The sampling probe shall be positioned at working level and air flow probe shall be directed vertically upward.
  • Where only one sampling location is determined, minimum of location shall be considered.

Acceptance Criteria: All the clean rooms should comply as per the designed class at rest as per ISO 14644 & WHO TRS 961.
Recovery Test:
  • The recovery test shall be performed by qualified and trained person only.
  • Measuring instrument being used shall be calibrated with reference to NPL/NABL traceable reference standard.
  • Locate the particle counter in the highest particle count location identified in particle count test.
  • Switch “off” air handling unit of the room under test and adjacent rooms.
  • Start particle counter and take sample till particle count reaches beyond the acceptance criteria.
  • Evaluate the hold time that subjected area will remains with clean room class.
  • When the particle count level reaches more than the specified class limit, switch “ON” the Air Handling Unit of the room and adjacent rooms immediately. Switch on the particle counter.
  • Record the particle count each minute until the cleanliness level in the room is restored to the original condition & recorded the recovery time.

Acceptance Criteria: Hold time shall be established. Recovery time should not be more than 15 minutes.
Air Flow Pattern:
  • The air flow pattern test shall be performed by trained and qualified person only.
  • Ensure area should be in rest condition and all equipment’s are covered before starting test.
  • Switch on the fogger. Wait till smoke comes out.
  • Place outlet of fogger near supply grill and ensure that smoke should be sufficient for visualization.
  • Record the room name, room identification number and differential pressure reading on measuring device (if applicable).
  • Record the air flow pattern and direction through video camera, gradually move fogger outlet from supply to return air grill and record the same.
  • To check and record pressurization, open door slightly and move fogger outlet near doors.
  • Ensure air should move from high pressure zone to lower.
  • Ensure recording should be sufficient to demonstrate the air flow direction and pattern.

Acceptance Criteria:
Smoke should flow through these critical areas in uniform and unidirectional pattern. If the smoke return or back flow due to turbulence, system cannot be accepted and must be rebalanced or readjusted.
Results:  The CD of the video clip shall be kept as the part of the performance qualification and attached with the report.
Temperature and Relative Humidity Mapping: 
Purpose of this to provide guideline to carry out temperature and relative humidity mapping and to identify the location of minimum (Coolest Point) temperature and maximum temperature (Hottest Point) during temperature mapping and affixing Hygrometer/ Thermometer at hot point location for routine monitoring purpose of temperature and relative humidity of the area.
Factor that may be raise extremes of Temperature are:
Size and Space: Large open space to maintain consistent temperature
Location of the air supply unit: Material stored neared the supply unit may be cooler than those far away.
Sun-facing wall: Areas near the exterior wall may be warmer.
Door location and handling: Door which is left open or handled maximum time in summer season.
Geographic location: Extreme temperature extraneous vary based on the geographical location. 
Location of Data Logger:
  • Temperature and Relative Humidity mapping process follow as-
  • Air Handling Unit (Air conditioner) shall be in running condition up to end of the temperature and relative humidity mapping.
  • Set the temperature 25°C in all air supply units and maintained the temperature of the area NMT 25°C .
  • Set the relative humidity 55 % in all air supply units and maintained the relative humidity of the area NMT 55%.
  • Set the temperature 25°C and relative humidity 55% in all data logger used in the area.
  • Set the monitoring frequency of every 10 minutes.
  • Once the entire data logger affixed at the identified location activate the data logger and note down the time.
  • Allow the data logger for 72 hours.
  • Attached the observation of temperature and relative humidity .
  • Review the temperature & RH mapping data and find out hot point, at hot point location put the hygrometer for routine monitoring of temperature and relative humidity of the area,

Pressure differential:
Measurement of differential pressure shall be done to ensure that pressure differential of area is sufficient to prevent movement of air from less clean to more clean area. Higher quality clean room shall have a higher-pressure than less clean area.
Ensure the availability of number of air changes is as per design of the area.
Ensure that prior to start of recording of observations, doors or opening area closed.
Ensure that the Magnehelic gauges used for measurement are calibrated.
Record the observations at every hour’s interval for 48 hours.
Acceptance Criteria: Pressure Differential was as per the approve design of the facility (Between 5 Pa to 15 Pa as per WHO TRS 961). Refer design qualification chart for the pressure differential values in each area as per design.
Results: Record the Observation in Annexure IV.
Viable Air Microbial Count (Bio burden):
The test shall be undertaken to demonstrate that   the bio burden concentration is not exceeding by using Settle plate technique and air sampling technique. The test was undertaken only in the operational state as the main source of viable microbial load is the personnel working in the area.
Perform the Environmental monitoring by the following two methods:
Active Sampling (By Air Sampler Method)
Passive Sampling (By Settle Plate Method)
Frequency for environment monitoring by Air Sampler method is daily during performance qualification for continuously one weak.
Location for the air sampler and by settle plate method is as per environmental monitoring SOP.
  • Active Sampling (By Air Sampler Method)
  • Prepare the pre-incubated Soyabean Casein Digest Agar plates as per respective SOP. and label the plates for details of “Sampling location, Date of exposure, and exposed by.
  • Sterilize the Air sampler accessories in an autoclave at 121+3oC for 30 minutes and put the sterilize accessories, sterile gloves and mask in S.S container.
  • Wear the Sterilize gloves and mask and Place the autoclaved SS cone inside the Air Sampler and place the prepared plate in position (without lid).
  • Place the SS feeder cone circular clamp assembly in position. Select vertical or horizontal mounting position. At the end of the sampling period (1000 litres/8min) close the lid of the plates.
  • Transfer these plates to the Microbiology Lab and incubate plates in an inverted position at 20-25°C for 72 hours followed by 48 hours at 30-35°C.
  • After completion of incubation period record the observations Annexure- V.
  • Acceptance Criteria: By Active Sampling Method for grade “D”, class 100,000 NMT 200 CFU/ m3.           

Passive Sampling (By Settle Plate Method)
Prepare the pre-incubated Soyabean Casein Digest Agar plates as per respective SOP. and labels the plates for details of “Sampling location, Date of exposure, and exposed by.
Wrap the labelled plates in aluminium foil and put in a caped S.S. container with Sterilize gloves and mask.
Open the plates aseptically and expose the plates on SS Stand for four hours.
After four hours’ exposure, cover the lid of plate aseptically and wrap with aluminum foil and place in the SS container.            
Carry the plates to Microbiology lab for incubation at 20-25 Degree C for 72 hours followed by incubation at 30-35 Degree C for 48 hours.
After incubation, take out the plates and count the colony forming units (cfu) with the help of colony counter.
Acceptance Criteria: By Settle Plate Method for Grade “D”, Class 100,000 NMT 100 CFU/plate 4hours.
Performance qualification Acceptance Criteria:
Performance qualification shall be considered acceptable when all the conditions specified in various sections have been met.
Any deviation from the acceptance criteria of the specific check point shall be reported and decision should be taken for the rejection, replacement or rectification of the equipment/component.

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