If you work in a laboratory, then you know how important it is to maintain an aseptic environment. Whether you’re using a wire loop or a pipette, it’s imperative to contain the infectious materials that are produced by many microbiological procedures.
Laminar air flow is defined as air moving at the same speed and in the same direction, with no or minimal cross-over of air streams (or “lamina”). Most laboratories that are sensitive to contamination require laminar flow hoods because it moves particles in the same direction- from the cleanest area from under the hood to the exit area. This particular design provides the cleanest, most germ free laboratory environment possible.
So, how do laminar air flow hoods work, and how do you know which one is best for your needs?
How a Flow Hood Works
It’s important that your flow hood is working properly, but how does it work, anyway?
A laminar air flow hood consists of a filter pad, a fan and a HEPA (High Efficiency Particulate Air) filter.
- The fan pulls the air through the filter pad and traps dust.
- Next, the dustless air passes through the HEPA filter that removes fungi, bacteria and other contaminants from the air.
- Finally, the sterilize air flows through your work area where you can work and do all of your flasking without risk of contamination.
To maintain an aseptic environment, the HEPA filter on your hood must remove all air borne materials, and the air speed within your work area must be about one-half m/s.
Flow Directions of Laminar Flow Hoods
Now that you know the basics of how a laminar air flow hood works and why it will be beneficial to your laboratory, you need to decide if a vertical or horizontal air flow is best for your work/flasking area.
Vertical Flow – the air migrates from the top of your work area to the bottom and exits the work area through holes in the base. This type of hood provides protection to your laboratory personnel and cultures.
Click HERE to see RDM Laminar Flow Workstations
Pros:
- Uses less floor space because the hood is not as deep.
- Can be used when compounding sterile products.
- Added safety for your personnel because the air is not blowing directly on them, and a sash in front of the operator’s face provides a barrier.
- The filter is on top of the unit, which provides easier access when changing the filter.
- Less effects on objects and processing equipment from air turbulence.
- Reduced cross contamination of items on your work surface.
Cons:
- May need to use a step ladder during filter change or maintenance due to overhead clearance requirements.
- Cannot obstruct airflow by placing hands or items on top of other items.
- Increased effect of turbulent airflow due to air striking your work surface.
Horizontal Flow – the air migrates from the back of your work area to the front. This type of hood provides protection to your culture if the air is flowing towards your personnel, or to your personnel if the air is flowing towards your culture, but not both.
Click HERE to see RDM Laminar Flow Workstations
Pros:
- Reduced effect of turbulence or air striking to your work surface.
- No sash makes it easier to work and position your equipment.
- Hands, gloves and other safety equipment are usually less contaminating because they’re downstream of your sample.
Cons:
- Air blows directly on your personnel.
- Filter change and maintenance will most likely require repositioning of your laminar flow air hood for rear access.
- Working with larger samples can obstruct airflow and can possibly contaminate samples that are downstream.
- Can blow fumes and/or powders into your personnel’s face.