Where particle contamination is specified as a potential quality
issue, laminar flow offers a design solution.
Laminar flow is the directional control of filtered gas passing
from a discharge point to a receiving point, where the critical
flow is between the two points.
In reality, for the laminar flow to be effective, the gas flow
must remain uniform over the entire critical work area to discharge
any particulates along with the discharge gas.
Turbulence in the gas flow causes a backwash of gas and is a potential
source of redistribution of particulate from the work surface, process
material or handling equipment. The point of gas discharge and receiving,
therefore become important features in the design for system efficiency.
Another factor of choice is for vertical or horizontal gas flow
and this much depends upon the process application, material and
work practice. Gas velocity is also important in maintaining uniform
In considering the design it must be established to what degree
the gas needs to be filtered from a choice of options, but this
can be simplified by opting for commercially available filters in
the HEPA or ULPA range, with popular filters rated 99.99% efficient
at removing particles down to 0.3 micron in the former and 99.999%
efficient at removing particles down to 0.12 micron in the latter.
Laminar flow gas systems are usually specified for the most stringent
clean working conditions typically found in electronic industries
handling semiconductors, and in pharmaceutical industries.
Laminar flow gas can be the source of a build up of static charges,
which can have a marked effect on the behaviour of particulate.
Solutions for neutralising this can be integrated into the design