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SOP for Laminar Air Flow Workbench

Standard operating procedure of Laminar Air Flow used for microbial analysis.


       To describe the procedure for the Laminar Flow Air.

2.0  SCOPE

       This SOP is applicable for Procedure for the Laminar Flow Workbench.


       Microbiologist - Quality Control


       Manager - Quality Control


5.1  General cleaning:

5.1.1  Clean the exposed surfaces of the Laminar air flow first with a clean dry cloth/ tissue paper followed by a wet mop of either 2.5 % dettol or 70 % Isopropyl alcohol solution on rotation basis. 

5.2  Cleaning of filters: 

5.2.1  Laminar air flow has two filters i.e. Pre-filter and HEPA filter (High Efficiency Particulate Air Filter). 
5.2.2  In case the magnehelic gauge indicates the filter choking, the Pre-filter shall be cleaned using a vacuum cleaner. 
5.2.3  Pre-filter shall be checked once in three months for accumulation of dust. 
5.2.4  Pre-filters shall be washed with a mild detergent and dried, if excessively dirty. 
5.2.5  HEPA filter shall not be touched or opened by the laboratory personnel. 
5.2.6  An authorized service engineer who shall also check for any rupture of the HEPA filters shall service the LAF bench annually. 
5.2.7  A proper record of cleaning and servicing shall be kept by microbiologist and preserved for a minimum of two years. 

5.3  Operation 

5.3.1  Clean the exposed surfaces of L.A.F first with a clean, dry cloth/ tissue paper. Then clean the exposed surfaces with a wet mop of either dettol solution or 70% IPA. 
5.3.2  Switch ON the main switch of L.A.F. 
5.3.3  Turn the knobs of Air flow and U.V. lamp to ‘ON’ position and ensure that the pressure reading is between 7.0 to 15 mm. 
5.3.4  Keep the U.V. lamp and Air Flow 'ON' for 30 min before start of work. 
5.3.5  After 30 min put 'OFF' the U.V. lamp and put 'ON' the normal light in the L.A.F and then start work. 
5.3.6  After completion of work in LAF bench, again clean it with dettol solution or 70% IPA. 
5.3.7  Turn the knobs of Airflow and light to 'OFF' position and put 'OFF' the main switch of LAF. 

5.4  Monitoring of microbial contamination 

5.4.1  Media required Nutrient agar (NA)/Soyabean Casein Digest Agar (SCDA) for bacteria and Sabouraud's dextrose agar (SDA) for fungi. 
5.4.2  Rehydrate the dehydrated media as per the manufacturer's instruction given on the bottle label and sterilize at 15 Lbs, 121°C for 20 minutes or as per validated cycle Dispense about 20-25 ml of the media into sterile Petri dishes and allow to solidify as per SOP. 
5.4.3  Switch on the LAF & follow the point 5.1. 
5.4.4  Before working in LAF rinse hands with 70% IPA v/v and wear nose mask and hand gloves. 
Plate exposure locations5.4.5  Place 5 pre-incubated Nutrient Agar/SCDA plates and 5 preincubated Sabouraud's dextrose Agar plates, one on each corner and one in the centre of the LAF bench.
5.4.6  Open the plates taking care not to introduce any extraneous contamination into the media. Expose for NLT 30 minutes.
5.4.7  After exposure, cover the plates with the lids and number them appropriately so as to indicate the position of the plate on the LAF bench. 
5.4.8  Incubate the Media plates at 30°C - 35°C for 48-72 hours and further for 48-72 hrs at 20-25°C. 
5.4.9  Also incubate one plate of each media at the same temperature for the same time to serve as negative control. 
5.4.10  After incubation, check the plates for growth and record the observation (as per Annexure - II). 
5.4.11  If no bacterial or fungal growth is observed, then the LAF is OK. 
5.4.12  If any growth is observed, repeat the monitoring twice. 
5.4.13  If growth is still persistent, stop using the LAF with immediate effect and inform the Engineering department/supplier for rectification. 

5.5  Frequency of monitoring

5.5.1  Once in 15 days and after every maintenance job by exposing sterile media plate. 
5.5.2  Calibration of air velocity & integrity testing of HEPA filter is done on contract every six months.

5.6  Preservation of record

5.5.1  A proper record of sterility monitoring, failure of LAF bench, breakdown and rectification, if  any, shall be documented by microbiologist and shall be preserved for two years.


6.1  SOP - Standard Operating Procedure
6.2  HEPA - High Efficient Particulate Air 
6.3  LAF - Laminar Air Flow 
6.4  SDA - Soybean Casein Agar 
6.5  SCDA - Soybean Casein Digest Agar 
6.6  IPA - Isopropyl Alcohol

                                                                 ANNEXURE – I
                                                                LAF USAGE LOG
Manometer Reading/ Magnelic Gauge mm
(7.0 to 15.0)
UV light usage hours
Start time
Off Time
Used by
Checked by

                                                                ANNEXURE – II
Inst. ID  No.

Ref.  SOP No.


Model No.

Date _____________
Medium Used                         :
Plate Exposed For                   : 30 Minutes
Plate Incubated At                  : 32.5 °C  / 22.5 °C + 2.5 °C
Plates Incubated For               : 48 Hrs. / 5 Days
Frequency                               : Once In 15 Days
Positive Control                       :
Negative Control                     :
Limits  : No Growth Should Be Observed In Any Plate.
S No.
Result after48 hrs at 30 - 350 C (cfu)
Result after 72 hrs at 20 - 250 C (cfu)
Organism Found

REMARKS : The above mentioned laminar flow is working / not working satisfactorily and does not require / requires maintenance work.
Date:                                                      Done By:                                                       Checked By:
Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
Email: .moc.enilediugamrahp@ofni Need Help: Ask Question

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