A laminar flow hood provides a controlled environment for sensitive work by maintaining a continuous flow of highly filtered air. This specialized workstation is designed to create a sterile or particle-free zone, which is particularly important in fields such as microbiology, cell culture, and pharmaceutical compounding. The primary function of these hoods is to protect the materials or samples being handled from airborne contaminants, ensuring the integrity of experiments and products. By directing a unidirectional stream of air, typically filtered through a High-Efficiency Particulate Air (HEPA) filter, the hood sweeps away dust and microbes, preventing them from settling on the work surface.
Before You Begin
Proper preparation is fundamental to using a laminar flow hood. Clear the immediate area around the hood to prevent airflow disruption or contaminant introduction. This establishes a clean boundary before activation.
Thoroughly clean the hood’s interior surfaces. Use a suitable disinfectant, such as 70% ethanol or isopropanol, applied to a lint-free cloth. Wipe systematically, starting from the cleanest areas, like the back wall or ceiling, and moving towards the front. Avoid spraying cleaning agents directly onto the HEPA filter, as this can cause damage. Allow sufficient contact time for the disinfectant to work, typically 10 minutes.
Gather all necessary materials and equipment, organizing them efficiently within the hood’s working area. Place items to avoid obstructing unidirectional airflow, generally at least six inches from the front edge. Overcrowding disrupts laminar flow and compromises sterility. Wipe all items with 70% ethanol before placing them inside to minimize contamination.
Personal protective equipment (PPE) is necessary. Don a clean lab coat, gloves, eye protection, hair covers, and a face mask if required. This attire protects the user and work from particles and microorganisms shed from skin and clothing. Finally, perform a quick visual check for damage to the hood or filters, ensuring the unit is properly plugged in before activation.
Working Inside the Hood
Once preparations are complete, activate the laminar flow hood and allow it to run for a “purge time” before beginning work. This typically ranges from 10 to 30 minutes, permitting airflow to stabilize and clear contaminants.
When placing items within the hood, position them optimally to maintain laminar flow. Avoid placing large objects directly in front of the HEPA filter or blocking air vents, as this creates turbulence and compromises the sterile zone. In horizontal flow hoods, placing items closer to the back offers more protection. In vertical flow hoods, avoid placing hands directly above sensitive samples to prevent contamination from downward airflow. Arrange materials for a smooth workflow, moving from cleaner to potentially less clean items, reducing cross-contamination risk.
Maintain proper working technique to preserve the sterile environment. Make slow, deliberate movements within the hood to minimize air turbulence; rapid motions disrupt laminar flow. Avoid reaching over sterile items or crossing your arms over the work area, which introduces contaminants from non-sterile gloves or clothing. All aseptic manipulations should be performed at least six inches inside the hood’s front edge to ensure they occur within the zone of purified air.
Adherence to aseptic principles is paramount. Protect sterile materials from contact with non-sterile surfaces or items. When opening sterile packaging, do so within the hood’s confines and discard outer wrappers outside the sterile zone. When handling tools or solutions, ensure only the sterile parts contact your samples.
Manage waste generated during your work by placing it in designated containers within the hood, ensuring it does not obstruct airflow or contaminate sterile items. Some waste, like used pipette tips or contaminated wipes, should be immediately removed from the active work area to maintain cleanliness.
After You Finish
After completing work inside the laminar flow hood, follow specific procedures to decontaminate the workspace and prepare the hood for its next use. Carefully remove all materials and equipment, ensuring any waste is properly segregated and disposed of according to laboratory protocols.
Thoroughly decontaminate the hood’s interior surfaces with an appropriate disinfectant, similar to pre-use cleaning. Wipe down all surfaces that were part of your working area, moving from the cleaner back sections towards the front.
Once cleaning is complete, initiate the shutdown procedure for the laminar flow hood. While specific instructions vary by manufacturer, this generally involves turning off the fan and lights. Some facilities may leave the hood running continuously to maintain a clean environment, while others shut it down daily.
General safety practices related to laminar flow hoods and laboratory environments should be observed. Ensure personnel are trained on proper handling and operation, as misuse compromises the sterile environment and leads to contamination. Regular cleaning and adherence to protocols are crucial for equipment longevity and user safety. Report any signs of wear, damage, or malfunction to appropriate personnel; routine checks and professional certification ensure the hood’s continued effectiveness.