SOP on Operation, Calibration, Cleaning and Maintenance of LAF

SOP on Functioning, Calibration, Cleaning, and Maintenance of LAF


  • Technique for functioning, Calibration, Cleaning, and Maintenance of LAF.


  • This SOP is relevant for the Operation, Calibration, Cleaning, and Maintenance of LAF in the Microbiology Laboratory.


  • Chemist or above of Microbiology Laboratory.
  • Head – Microbiology Section.


  • Head – Quality Control.



Laminar airflow (LAF) is equipment that is commonly used in pharma Industries. LAF consists of a chamber with an air blower fixed to its rear side that supplies the flow of air with a uniform velocity in straight lines that are parallel to each other. The main Objective of a LAF is to facilitate a contaminant-free work environment. Filters are installed in LAF that have captured all types of foreign particles entering the cabinet. LAF makes use of a filter pad and a special filter system known as a high-efficiency particulate air filter or HEPA filter, which can remove the airborne particles up to 0.3 micrometers airborne particles in size.

LAF is fabricated to protect the work from the elements and is fit for the aseptic activity of certain media as well as pouring plates. LAF cabinets and biosafety cabinets both function same principle, the only difference is that in biosafety cabinets, the air that is emitted is drawn directly into the person’s face. In a biosafety cupboard, both the user and the test sample are protected but in a laminar flow cabinet, only the sample is secured but not the user.

  • Laminar Air Flow Chamber Consist of the following Parts that is –
    • Cabinet
    • Working Station
    • Filter Pad
    • Fan or Blower
    • HEPA Filter
      • Interception
      • Impaction
      • Diffusion
    • UV Lamp
    • Fluorescent Lamp

1. Cabinet

It is fabricated of stainless steel and has minimum or no gaps or joints, which protect against the accumulation of spores. The cabinet function as an insulation for the inner surroundings that is created within the laminar flow. Cabinet also protects it from the outside environment. The cabinet’s front is enclosed with a shield of glass that can be opened completely, even as others have two holes for users’ hands to access the cabinet.

2. Working station

A flat workplace is facilitated inside the LAF cabinet for the procedures to take into consideration. Burners, culture plates, and loops are set in the workplace, where the process takes place. The worktop is built of stainless steel with the intention to keep it away from corrosion.

3. Filter pad/ Pre-filter

Filter pads are placed withinside the higher a part of the cabinet so that air can go into the cabinet. The filter pad is used to hold microbes and dust particles from coming into the workplace inside the cabinet.

4. Fan/ Blower

A fan is located below the filter pad, absorbs air, and moves it inside the cabinet. The fan additionally helps the air to transport in the direction of the HEPA filter, which ensures that remaining microbes get captured after moving across the.

5. UV lamp

Laminar flow hoods also have a UV germicidal light for sterilizing the inside of the cabinet as well as its materials prior to the procedure. The UV lamp of LAF is to be switched on for 30 minutes prior to the time of the activity and should be switched off before activity to ensure that there is no exposure to UV radiation on the body surface of the person.

6. Fluorescent lamp

The fluorescent lamp is a light source that is fitted inside the cabinet to provide sufficient lighting during operation.

7. HEPA filter

The high-efficiency particulate filter is fitted inside the cabinet. HEFA filter makes the atmosphere safer to ensure smooth operation. The air that has been pre-filtered and intermediate filter passes through the filter that traps bacteria, fungi, and dust particles. The HEPA filter guarantees a clean environment inside the cabinet, which minimised the chance of contamination.

Three Types of a Laminar Air Flow Chamber is used in Pharma Industry

    • Vertical Laminar Air Flow Chamber
    • Horizontal Laminar Air Flow Chamber
    • Wall to Floor Air Flow System

Vertical Laminar Air Flow Chamber

In this cabinet, air flows thru the top part of the cabinet toward the lower part in the cabinets. A vertical airflow bench doesn’t require as much space in the floor and depth as an airflow hood that is horizontal, which makes it simple to handle and decreases the risk of obstruction to airflow or the movement of air contaminated downstream. Vertical laminar flow cabinets are to be safer because it doesn’t blow air directly toward the person performing the tests.


  • Less area of floor requirement for Hood.
  • Safety: Air does not directly hit the user, while each acts as an obstruction between the face of the operator
  • The filter on top makes it easy to handle
  • A less turbulent effect of the impact of air on big objects, processing machines, or other equipment
  • There is less cross-contamination of the material that is kept in the workplace.


  • Due to height during changing, filters or preventive maintenance of equipment may require a step-ladder
  • Do not place hands or materials over other materials to obstruct airflow
  • A higher degree of turbulent effect from air hitting work Place.


Horizontal laminar flow cabinet

In horizontal LAF cabinets, the air comes from behind the bench. It is carried by the blower toward HEPA filters. The filtered air comes horizontally toward the work area and working environment. The benefit of this kind of LAF cabinet is airflow running parallel to the workplace cleans the surroundings at an unchanging speed. The air that is emitted directly strikes the user, which could minimize the security levels of these laminar flow cabinets.


  • Laminar airflow that runs parallel to the workplace will eliminate the turbulent effects of the vertical airflow that strikes perpendicularly to the workplace
  • Easy to move and move sterile equipment and other materials closer to the face of the filter (upstream from any other contaminants)
  • Hands and gloves are less likely to be contaminated since they’re just downstream of the sample


  • Service or filter change normally requires repositioning of the hood to permit rear access
  • Large samples impede laminar airflow, and might also additionally contaminate downstream samples


Wall to Floor Air Flow System



  • Plug in the LAF to the Mains Power supply and switch ON the mains.
  • The front panel of the LAF includes the subsequent buttons
  • Power the ‘ ON’ button of UNIDIRECTIONAL FLOW to turn  ON the blower.
  • Power the ‘ON’ button of FLUORESCENT LIGHT to turn ON the Light.
  • Power the ‘ON’ button of the GERMICIDAL LIGHT to turn ON the GERMICIDAL LIGHT.
  • Before Starting the work, Switch on the Blower and GERMICIDAL LIGHT for half-hour. After half-hour transfer off the GERMICIDAL LIGHT and Switch the FLUORESCENT LIGHT on. Then slowly uplift the the front door up, to open.
  • Monitor the Positive pressure analysis on the Magnehelic gauge. It has to be between 10 and 20 mm of water gauge.
  • Wipe the LAF Work bench with 70% IPA after the work as per requirement.
  • After completion of work, screen the pressure analysis on the Magnehelic gauge.
  • Clean the workstation with 70% IPA
  • Close the door.
  • Power ‘OFF’ button of FLUORESCENT LIGHT to turn OFF the Light.
  • Power ‘OFF’ button of UNIDIRECTIONAL FLOW to turn OFF the Blower.
  • Power the ON button of GERMICIDAL LIGHT to turn ON the GERMICIDAL LIGHT and keep it for 10 minutes.
  • Then Power the OFF button of the GERMICIDAL LIGHT to turn OFF the GERMICIDAL LIGHT.
  • Record the LAF usage in the format given as Annexure No. A01


  • Perform the calibration of Magnehelic gauge once a year through external agencies

Cleaning and Maintenance:

  • Clean the internal walls, grill, and workbench of the LAF Cabinet before beginning and after completion of every work with the assistance of lint free cloth dipped with disinfectant solution.
  • Clean the outer frame of the LAF with the usage of a lint-free cloth dipped with disinfectant solution twice (at the start and end of the day’s work).
  •  Remove the pre-filter from the LAF for Cleaning purposes.
  • Pre-filter shall be cleaned by a maintenance person once a month with compressed air and soap water.
  • Place the wiped clean Pre-filter at its position. Switch on the LAF unit. Check the positive pressure on the Magnehelic gauge. It should be in the middle of 10 and 20 mm water gauges.
  • If pressure analysis on the Magnehelic gauge is not achieved, put a status label `Under Maintenance’ & ask the Maintenance Department for necessary action.
  •  Change the HEPA filter of the LAF if the reading is above 20 mm of the water gauge

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List of Annexures / Formats:

S.No. Format Title Annexure Number
1 LAF Log Book A01
  • Reason for Revision:
  • Periodic review


  • SOP: Standard operating procedure
  • NO: Number
  • QC: Quality Control
  • QA: Quality Assurance
  • LAF : Laminar Air Flow

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