1. What is a Biological Safety Cabinet?
A biological safety cabinet (BSC) is a ventilated cabinet which uses a combination of
HEPA filtration, laminar air flow and containment to provide personnel, product or
environmental protection from biohazardous agents. This is accomplished by air intake
and recirculation that is filtered prior to exhausting to the cabinet exterior.
It is distinguished from a chemical fume hood by the presence of HEPA filtration and the
laminar nature of the air flow.
2. What is a Laminar Flow Cabinet?
A laminar flow cabinet or laminar flow hood or tissue culture hood is a carefully
enclosed bench designed to prevent contamination of semiconductor wafers, biological
samples, or any particle sensitive device. Air is drawn through a High Efficiency
Particulate Air (HEPA) filter and blown in a very smooth, laminar flow towards the user
or towards the work surface. The cabinet is usually made of stainless steel with no gaps
or joints where spores might collect. Laminar flow cabinets do not protect the user or the environment
and
cannot be used with infectious material.
3. What is a HEPA filter?
HEPA stands for High Efficiency Particulate Air filter and is capable of removing
microscopic organisms with an efficiency of at least 99.97%. These filters help protect
the user, the product in the workspace and the environment, but must be checked
annually to ensure that they are functioning properly.
4. What is a Cleanroom?
A Cleanroom is defined by ISO14644-1 as "a room in which the concentration of airborne particles is
controlled, and which is constructed and used in a manner to minimize the introduction, generation, and
retention of particles inside the room and in which other relevant parameters, e.g. temperature,
humidity, and pressure, are controlled as necessary." The design of cleanroom HVAC systems is a
specialty area requiring the unique understanding of cleanliness guidelines, airflow, room
pressurization, code requirements, specialty equipment, precise control, and many more details.
5. Describe Cleanroom Do’s.
Only authorized personnel will be allowed inside the cleanroom.
Only take what is necessary into the cleanroom.
Only dedicated tools are allowed in the cleanroom.
Gown in the prescribed manner over your non-frayed/non-ripped, low-linting clothes.
Always make sure that all the head/facial hair is covered inside the cleanroom.
When using an air shower, turn a minimum of three times around (slowly) during the
ON cycle time.
Keep doors from clean room to gowning area closed.
Keep the cleanroom garments closed at all times while in the cleanroom.
Use pass-through properly.
Maintain good air flow management. "Product gets air first."
Be discrete in coughing, sneezing, blowing your nose. If you can, go into the service
area or gowning room. At the very least, turn away from the processing area and
change your vinyl gloves before commencing processing again.
6. Describe Cleanroom Dont’s.
People who have not been trained properly to meet the cleanroom usage requirements
will not be allowed inside the cleanroom. The Cleanroom supervisor has the last word.
No cosmetics, tobacco products, handkerchiefs, tissues, food products, drinks,
wooden/mechanical pen/pencils, perfumes, colognes, watches, jewellery, cassette
players, phones, beepers, combs, cardboard or non-cleanroom approved papers are
allowed.
No blueprints, operation manuals or instruction sheets are allowed.
Do not bring any tools/ equipment into the cleanroom from the maintenance shop to
work in the cleanroom.
No bare clothes are allowed inside the cleanroom.
Do not expose any facial/head hair.
Do not open the door to the cleanroom until the ON cycle of the air shower is over.
Do not open the door to the cleanroom for communication or passing of products back
and forth – use the pass-through instead.
Do not use pass-through for storage.
Do not block the air flow from the filter to the product.
Do not congregate. No running and try to maintain silence.
7. What is Contamination?
Contamination is a process or act that causes materials or surfaces to be soiled with contaminating
substances. There are two broad categories of surface contaminants: film type and particulates. These
contaminants can produce a “killer defect” in a miniature circuit. Film contaminants of only 10 nm
(nanometers) can drastically reduce coating adhesion on a wafer or chip. It is widely accepted that
particles of 0.5 microns or larger are the target. However, some industries are now targeting smaller
particles.
8. What specifications or standards apply to testing the filters in place?
Latest ISO 14644 replaces FED Std 209E.
9. With reference to Fed. Std. 209b, What is the relationship of the various
classes of clean rooms ( 100, 10 000, and 100 000 ) to the 0.01% figure ?
There is no relationship at all. For example- a clean room with no one in it might be class 100, while
the addition of personnel will send it into other higher categories. however, suppose the filters
supplying a room were thoroughly checked for leaks, and all significant leaks were sealed, this room is
operating at maximum efficiency with respect to the filters, and since the filters are mechanical in
nature, there is nothing the operator can do to change conditions in this area.
The achievement of a particular class would relate to the number of air changes per hour as well as the
scavenging design of the system.
10. Define Validation.
Validation is the process of establishing documentary evidence demonstrating that a procedure, process,
or activity carried out in testing and then production maintains the desired level of compliance at all
stages. In the pharmaceutical industry, it is very important that in addition to final testing and
compliance of products, it is also assured that the process will consistently produce the expected
results.
11. How is Air Changes per hour is calculated in Cleanrooms?
Air Changes per hour= Average airflow velocity* × room area × 60 min/hr.
12. How often should I validate my cleanroom to meet ISO 14644-1:2015?
It states the maximum time interval between airborne particle concentration testing of a cleanroom of
ISO class 5 and below is six months and ISO class 6 and above is 12 months.
13. What are the clean room class limits according ISO Standard 14644-1?
work and in the production of precision parts for electronic or aerospace equipment.
In the clean room standard ISO 14644-1 "Classification of Air Cleanliness" the classes are based on the
formula:
Cn = 10N (0.1 / D)2.08 (1)
where Cn = maximum permitted number of particles per cubic meter equal to or greater than the specified
particle size, rounded to whole number N = is the ISO class number, which must be a multiple of 0.1 and
be 9 or less
D = is the particle size in micrometers
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