Sop for Laminar Air Flow

This Document describes (Standard Operating procedure)  Sop for Operation and cleaning of Laminar Air Flow in microbiology Section

Sop for Operation and cleaning of Laminar Air Flow

I. Purpose & Scope:

  • The purpose of this SOP is to lay down the procedure for cleaning and operation of Laminar Air Flow.    
  • This Standard operating procedure shall be applicable for Cleaning, Operation of Laminar Air Flow in the Microbiology section of Quality Control Department

II. Responsibilities:

• All Quality control personnel’s shall be responsible to follow and implement this SOP.

III : Introduction and Procedural Part :


The Laminar Air Flow, clean air work stations are intended to maintain a sterile work area essentially free of particulate contaminants in a microbiological testing laboratory.  Laminar air flow hood consist of filter pad, a fan, HEPA filter. The fan sucks the air through the filter pad where dust is trapped. After that the pre-filtered air has to pass the HEPA filter where contaminating fungi, bacteria, dust etc. are removed. Then the sterile air flows, into the working area of LAF.

Operation :

  • Clean the bench with 70% IPA.
  • Ensure equipment is in a clean state.
  • Switch on the main supply.
  • Start the blower/fan of (air flow), minimum 30 minutes prior to starting the work in LAF cabinet. Red indicator will glow to show that blower is on. Air will start to come through the HEPA filter. Ensure that the differential pressure on the display is within the limit, it should be between 7.5 to 13 mm of water. Record the reading in Annexure-I.
  • Switch on the UV lamp of LAF and run the UV light for minimum half hour (30 minutes). After exposure of 30 minutes, switch off the UV lamp. Record the UV burning time in minutes, Refer Annexure-II.
  • Check and ensure that the differential pressure is as per specified limit (7.5 to 13 mm of water) and Start the Microbiological testing under LAF workstation.
  • After completion of testing, clean the working table with 70% IPA.
  • At the end of the testing for the day, switch off the light and start the UV lamp. Expose the UV light for minimum 30 minutes. Record the UV burning time in minutes, Refer Annexure-II.
  • Switch off the UV lamp and Blower of the LAF cabinet.

Cleaning : 

  • Keep the LAF interior and exterior free from dust.
  • Before starting the work, clean the LAF interior with 70% IPA using non fiber shedding cloth.
  • Inside cleaning of the LAF is recommended in the following cases;
  • Before starting any work in the LAF cabinet.
  • After working in the LAF cabinet.
  • Whenever, there are changes of work program.
  • In the event of spillage on the worktable.

Cleaning of Pre-filters:

  • For Cleaning of the Pre-filter, remove the Pre-filter from LAF and then clean it as per respective SOP of Engineering.
  • Pre-filter shall be cleaned by Maintenance technician once in month with compressed air in Filter cleaning booth.
  • After cleaning, place the cleaned Pre-filter at its position.
  • Switch ‘ON’ the LAF Unit. Check the differential pressure on digital display. It should be between 7.5 to 13 mm of water.


  • Check the calibration status of the Differential pressure gauge.
  • Do not switch on the UV lamp during working period.
  • UV Lamp should be replaced after 5000 hours of U.V. burning.
  • Switch on the airflow of LAF workstation before 30 minutes of microbiological testing.
  • If differential pressure is less than or more than the Specified limit, inform to Engineering department immediately.

Frequency :

  • Differential pressure reading: At the time of ‘Switch ON.’
  • UV light burning reading: before ‘start’ and after ‘end’ of the activity.
  • Periodic LAF Requalification: Once in a year/ any major maintenance or replacement. (Perform Air Velocity, HEPA Filter Integrity, Smoke test, Non Viable Particulate count, Microbiological Contamination).


IV: Annexure : 

Annexure I: Differential pressure Record of Laminar Air Flow

Annexure II : UV Burning Record of Laminar Air Flow





Differential pressure Record of Laminar Air Flow


Instrument I.D.: _______________                                            

Date Time Differential Pressure

(mm of water)

Done By Checked By



Pre-filter Cleaning details :





UV Burning Record of Laminar Air Flow                                                                 


Instrument I.D.:_____________                                                       

Date UV lamp ‘ON’ Time UV Burning time (minutes) Total UV burning hours Done By Checked By

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