Laminar flow equipment uses HEPA filters to maintain sterile conditions by removing airborne contamination. It works by passing air through a HEPA filter, which removes 99.97% of particles 0.3 um or larger. The filtered air then flows uniformly into the sterile working area at a laminar rate of 100 ft/min. There are two main types - horizontal laminar flow cabinets where the filtered air flows horizontally across the work area, and vertical laminar flow cabinets where the air flows vertically down onto the work area. Laminar flow equipment is used in laboratories, especially medical and pharmaceutical facilities, to provide a sterile environment for sensitive work.

1. Laminar Flow Equipment
Anurag Gupta

2. Laminar air flow is an enclosed bench cabinet . It is designed to prevent
contamination of biological samples or any particle sensitive materials .
Laminar Flow Equipment
Principle
The air is passed through a HEPA filter
which removes all airborne contamination
to maintain sterile conditions.

3. Construction
It is low cost and does not require more space. The cabinet is made
up of stainless steel without gaps or joints thereby preventing the
buildup of bacteria from collecting anywhere in the working zone.
They are also known as clean benches because the air for the
working environment is thoroughly cleaned by the precision
filtration process. They consist of a filter pad, a fan, light with 100
lux and UV tube to disinfect the bacterial growth and a HEPA filter.
The fan sucks the air through the filter pad to trap the dust
particles. After that the pre-filtered air has to pass the HEPA filter
where all the microorganisms are removed 99.97% of airborne
particles 0.3 um in diameter. Finally, sterile air flows into the
working area without risk of contamination. The air flows at a
speed of 100 ft/min and sweep dust particles making entire room
free of particulate matter. This helps to perform work under
aseptic condition.

4. Air Flow Pattern
Generally air flow pattern in the clean rooms are of 3 types.
Air Flow Pattern
Unidirectional air
flow
Non-
Unidirectional air
flow
Combined air
flow

5. Unidirectional air flow is an air flow pattern in which essentially
the whole body of the air within a confined area moves with
uniform velocity and in single direction with parallel air streams
that means it is an airflow where a fluid flows in one direction
with no interruptions from turbulence. It should have uniformed
airflow at a speed of + 15% and the speed of the air is
measured as it exits the HEPA / ULPA filter
Unidirectional air flow

6. Non-unidirectional air flow is an air distribution
where the supply air entering the clean zone
mixes with the internal air by means of
induction. The room air change rate per hour is
calculated by the total airflow for the room is
divided by the room volume and a capture hood
is used to measure the volume of air exiting the
HEPA / ULPA filter
Non-unidirectional Air Flow

7. Combined air flow is a combination
of both Unidirectional and Non-
Unidirectional airflows
Combined Air Flow

8. Types
Mainly two types likely Horizontal Laminar Air Flow
& Vertical Laminar Air Flow

9. In this cabinet, the direction of air
flow comes from above but then
changes direction and is processed
across the work in a horizontal
direction. The constant flow of filtered
air provides material and product
protection
Horizontal Laminar Flow Cabinets

10. It is also same as well as horizontal
Laminar Flow Cabinets with the laminar
air directed vertically downwards onto the
working area. The air can leave the
working area via holes in the base.
Vertical flow cabinets provides greater
operator protection
Vertical Laminar Flow Cabinets

11. Uses
1) It has various applications, especially where
an individual clean air environment is
2) Required for smaller items, e.g., particle
sensitive electronic devices.
3) It is used for special operations in
laboratories.
4) It can be tailor made to the specific
requirements of laboratories and are also used
for general lab work, especially in medical,
pharmaceutical, electronic, and industrial
sectors.

12. 1. The persons working in the area do not feel the
movement of the air
2. The body of filters is made up of stainless steel
which is not favorable for bacterial growth.
3. The HEPA filter can reduce the contamination.
4. The sterile area is spacious.
5. Since the sterile area does not become hot, the
plant material can stay for a longer duration.
6. Bigger flasks having wide lids can be used.
Advantages

13. Limitation
The airflow velocity can be overcome easily
without any strict work practices and
aseptic technique, thus an area of
turbulence is created which can introduce
room contaminants particles and
microorganisms) into the critical work
area. A laminar air flow hood should
remain on for 24 hours. If it is turned off,
it should be left on for at least 30 minutes
for its disinfection before use.