Standard Operating Procedure for Operation and Cleaning of Reverse Laminar Air Flow (RLAF) and RLAF Filter

SOP for Operation and Cleaning of Reverse Laminar Air Flow (RLAF)
SOP for Operation and Cleaning of Reverse Laminar Air Flow (RLAF)

Standard Operating Procedure for Operation and Cleaning of Reverse Laminar Air Flow (RLAF) and RLAF Filter

1. Purpose:

To lay down a procedure for Operation and Cleaning of Reverse Laminar Air Flow (RLAF) and RLAF Filter.

2. Scope

The scope of this SOP is applicable for Operation and Cleaning of Reverse Laminar Air Flow (RLAF) and RLAF Filter at [company name].

3. Responsibility

Warehouse Person and QC Person: Operation as per laid down procedure.

Warehouse and QC supervisor: To monitor operations

Head Warehouse and Quality Control Laboratory: Effective implementation of SOP.

4. Definitions

Not applicable

Note: This reverse laminar air flow station re-circulate the air and provides containment by air movement, hence, it is also called as containment system

5. Procedure

• Operation of Reverse Laminar Air Flow:

• Switch on the main power supply and the lights of Reverse Laminar Air Flow (RLAF).

• Start the RLAF blower motor.

• Stabilize the RLAF and verify the magnehelic gauge or manometer readings to ensure that it is within the limit before starting the dispensing activity.

• Stabilization time of RLAF can be studied based on the validation and recovery studies. (Stabilization of RLAF is normally achieved within 10 to 15 minutes, hence, for safer side, organizations define the time around 30 minutes. However, based on studies, less than 30 minutes will be acceptable)

• Ensure that dispensing activities shall be done in the marked “Safe Zone”. Safe zone of RLAF is the area which is defined based on the validation studies. The safe zone is an area under RLAF where any material spillage occurs gets grabbed by RLAF filter and the mechanism prevents the possibility of area contamination.

• Material exposure shall be done under safe zone and personnel shall be standing outside the safe zone.

• Movements in the safe zone should be controlled while performing dispensing activity in RLAF.

• Once the activity completed, switch off the RLAF.

• Cleaning of Reverse Laminar Air Flow (RLAF) for dispensing of raw material:

• Once the dispensing is completed, all dispensed material shall be transferred either to manufacturing day store.

• Clean the loosely stuck powder from floor, walls and the balance platforms using vacuum cleaner and fresh lint free duster. The dust shall be removed from inner and outer surface of RLAF using vacuum cleaner or clean lint free duster.

• After that clean the inner and outer surface of RLAF using wet lint free dusters. Wetting of duster shall be done using purified water. If needed, lint free scrubber shall be used (ensure that the scrubber should not shred particles or damage the surfaces; nylon scrubber is preferably used).

• The inner and outer panels of RLAF shall be cleaned using lint free dusters with 70 % Iso propyl alcohol solution.

• After use, the scrubber shall be discarded (one time use).

• The RLAF shall be dried using compressed air or using dry clean lint free duster.

• Ensure that the powder aggregates and water splashes should not fall on the filters.

• The entries cleaning shall be made in equipment usage logbook.

• Cleaning of RLAF and dispensing area shall be done on daily basis before start of the dispensing operations. Entries shall be made in the RLAF equipment and area logbook.

• Cleaning of Reverse Laminar Air Flow (RLAF) used for dispensing of Packing Material.

• Dispensed material shall be transferred to respective packing department area

•RLAF shall be cleaned using vacuum cleaner and clean lint free duster wetted in purified water.

• Entries shall be made in the equipment cleaning logbook.

• Cleaning of RLAF Filters:

• To carryout filter cleaning operations, required PPE such as hand gloves, goggle, nose mask shall be used.

• Filter cleaning shall be done as per predefined frequency.

• Ensure that RLAF is switched Off and main supply of the RLAF is also Off.

• Open the pre-filter grill of RLAF. Pre-filter and intermediate filter shall be removed from the RLAF.

• Removed filters shall be put in the polybag. The filter kept in the polybag shall be taken to filter cleaning area.

• The filter shall be deducted under the filter cleaning hood. Ensure that filter cleaning hood blower is on and required vacuum is achieved to extract the duct from the filer cleaning are to dust collection unit.

• Once the de-dusting of filter is done, wash the filters using purified water and allow it to air dry/ or dry using compressed air.

• Pack the cleaned and dry filter in clean polybag.

• Before placement of cleaned filter in the RLAF, clean the inside surface of the RLAF using vacuum cleaner followed by wet duster (wetting to be done with purified water).

• The cleaned filter shall be re-installed in the RLAF.

• Once the filter installation is completed, clean the RLAF and area. Make entries in the respective area and equipment cleaning logbook.

• After completion of filter cleaning activity differential pressure across each filter type shall be checked for adequacy and compliance as per design qualification.

• After cleaning and installation of filter, magnehelic gauges or manometer reading should be within the specified limits as per SOP.

• Any concern observe, inform to the engineering department through maintenance memo.

• Cleaning of filter shall be done on once in a week.

• Ensure that filters cleaned schedule and frequency is maintained.

• Procedure for handling pre filter for high potent drug molecule (Low PDE value, ≤10 mcg/day) product:

• Dedicated pre filter shall be used for dispensing of material having low PDE value (≤10 mcg/day). 

• Remove and clean the installed filter and store them in cleaned polybag. Close it. Install the dedicated pre filter for respective materials having low PDE (≤10 mcg/day) value materials.

• Keep the filter in single polybag and close the bag using plastic seal.

• Before taking the filter to washing area, place the filter covered in the polybag in the second polybag. Close the bag using plastic seal. Take the filter to filter cleaning area.

• Product to product change over shall be done before and after dispensing of materials having low PDE (≤10 mcg/day) value..

6. Frequency

Manometer or magnehelic gauge reading limit and cleaning schedule

GaugeAcceptable Range in mmwcCleaning Frequency
Pressure behind pre filters1 – 3Weekly ± 1 days
Pressure across intermediate filters2 – 6Every 3 Months ± 5 days
Pressure above HEPA Filter8 – 12Not applicable (HEPA filter integrity to be done once in a year)

7. Formats

7.1 RLAF filter cleaning record.


Name of the Filter          

Filter No.            


Cleaned    by     

Magnehelic gauge pressure reading (in mm of wc) across pre-filter

Magnehelic gauge pressure reading (in mm of wc) across intermediate

Checked by       

Next due on                      

7.2 List RLAF filter.

Sr. No. 


Room No.

Filter No.

7.3 List of potent material having low PDE (≤10 mcg/day) values.

Sr. No. 

Material Name 

List Prepared By List Checked

Reference and to read more:

  2. Standard Operating Procedure for Dispensing of Raw Materials in warehouse
Scroll to Top