LimsPulse
Microbiology & sterility

Laminar air flow unit (LAF)

A work station that blows HEPA-filtered air in a uniform, one-directional stream over the work surface to give an ISO 5 / Grade A zone for aseptic handling of media, samples and sterile materials.

  • Pharmaceutical
  • Biotech
  • Hospitals and compounding pharmacies
  • Electronics
  • Food & beverage
  • Research laboratories
Photo of a Laminar air flow unit (LAF)
Photo: Hugh Fox, CC BY-SA 2.0 (cropped), via Wikimedia Commons
TROUBLESHOOTING

Common problems, causes and fixes

Low air velocity
Likely causes
  • • Blocked or loaded pre-filter or HEPA filter
  • • Fan speed set too low or motor fault
  • • Obstruction in front of the filter face
What to do
  • • Replace the pre-filter and check differential pressure
  • • Adjust fan speed and re-measure
  • • Replace the HEPA filter if loaded, then re-qualify
High particle counts in the work zone
Likely causes
  • • HEPA filter leak or damaged seal
  • • Turbulence from room air or operator movement
  • • Unit switched on too recently
  • • Dirty work surface
What to do
  • • Run a HEPA integrity (aerosol) test and repair or replace the filter
  • • Check room airflow, close doors and reposition the unit
  • • Allow the full stabilisation time
  • • Clean the unit and repeat the count
Microbial growth on Grade A settle or contact plates
Likely causes
  • • Poor aseptic technique
  • • Inadequate cleaning or disinfectant contact time
  • • Airflow disturbed or filter leak
  • • Contaminated plates or materials
What to do
  • • Raise a deviation and investigate as per the EM procedure
  • • Identify the organism to find the likely source
  • • Check air velocity and filter integrity
  • • Review cleaning and operator training
Differential pressure gauge reading rising
Likely causes
  • • HEPA or pre-filter loading with dust
What to do
  • • Replace the pre-filter first
  • • If the reading stays high and velocity drops, plan HEPA replacement
Differential pressure suddenly drops
Likely causes
  • • Filter seal failure or torn filter
  • • Fan failure or belt slip
What to do
  • • Stop using the unit
  • • Inspect the filter and fan; call service; re-qualify after repair
Alarm or unusual noise from the blower
Likely causes
  • • Worn motor bearing
  • • Loose panel or fan imbalance
What to do
  • • Switch off and call maintenance
  • • Do not use until the fault is fixed and velocity is re-checked
In LimsPulse · Calibration Management

Keep every LAF in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.

See how