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Cleanrooms
A cleanroom is a special room that's super clean! It keeps dust, germs, and other tiny things out of the air. This is important because some jobs need things to be very clean, like making computer parts or medicine. To keep things clean, these rooms have special filters and air systems that blow clean air around the room. We can build and put in these cleanrooms for all sorts of uses!
CLEANROOMS USER?
Cleanrooms are used across a variety of industries where a clean, uncontaminated environment is required.
Some of these industries that commonly use cleanrooms are:
SEMICONDUCTOR
The SEMICONDUCTOR industry utilizes cleanrooms to ensure the exclusion of contaminants in the manufacturing process. The industry also uses cleanrooms to create a clean environment for wafer fabrication.
FOOD
MEDICAL DEVICES / MEDICINE LAB
OPTICS
AEROSPACE
SOLAR
CHEMICAL
PHARMACEUTICAL
AND MANY OTHER
CLEANROOM CONSTRUCTION METHODS
MODULAR CLEANROOMS:
Modular cleanrooms are the most efficiently method of contemporary cleanroom construction. They are made of prefabricated many of cleanroom components that are manufactured offsite.
CLEANROOM AIRFLOW
Cleanrooms utilize air pressure, positive and negative, to control contaminants entering or leaving the room.
POSITIVE AIR PRESSURE CLEANROOM:
A positive air pressure cleanroom is an enclosure where the internal atmospheric pressure is greater than that of the exterior. This is accomplished by introduce treated clean air into the room, typically through MAUs and ducting system to the room’s ceiling following by fan filter unit (FFU).
Positive air pressurization rooms keep contaminants out when a door is opened, as clean air rushes out. The external air is kept away from entering the room by the room’s higher air pressure.
This can be like the air pressure in a car tire. As the air in the tire is under pressure, when you release the tire’s air by depressing the valve, air forced out, but none is allowed to enter to the tire — until the atmospheric pressure in the tire and the external ambient air pressure are equalized.
NEGATIVE AIR PRESSURE CLEANROOM:
A negative air pressure return chase is a room where the air pressure inside the room is lower than that of the clean room. This is achieved by forcing air to exit the clean room through return chase using FFU.
Generally, the negative air forcing through floors or louver and travelling through FFU (fan filters unit) above ceiling or extract by fume exhaust.
Negative pressure rooms (return chase) are intended to keep any contaminants from escaping the room unfiltered. These rooms are used to keep harmful particles or contaminants from entering communal air.
Clean Room Air Flow Diagram
LAMINAR AIRFLOW:
Laminar airflow is defined as air that flows in a straight and unimpeded path. Also referred to as unidirectional airflow.
Cleanrooms utilizing laminar airflow rooms intake air can be design by using laminar airflow hoods that direct the airflow straight down to be exhausted through exhaust fans placed in the floor or Using FFU above ceiling method. Designing a laminar airflow cleanroom is a complex task.
Ensuring the least amount of turbulence as the air navigates through a room of furniture, devices, and people is a matter of expert engineering and architecture.
NON-UNIDIRECTIONAL AIRFLOW:
Non-unidirectional, or turbulent, airflow rooms use non- linear airflow. This random movement of air helps to separate particles from the air and into the filtration system.
Both types of filters seem very similar upon first glance. Both use a dense layer of fibers and mesh to trap contaminants as air is forced through the filter. Additionally, both types of filters use the same three methods to trap airborne particles: diffusion, interception, and inertial impaction.
Although the two may seem the same, each filter has some unique characteristics that make them suitable for a variety commercial cleanroom applications.
ULPA FILTERS: Ultra-low particulate air (ULPA) filters are pleated mechanical filters that can trap at least 99.999% of dust, pollen, mold, bacteria, and other airborne particles with a size of 0.1 microns (0.1 µm).
HEPA FILTERS: High Efficiency Particulate Air (HEPA) filters are a pleated mechanical air filter. They are capable of trapping 99.97% of dust, pollen, mold, bacteria, and other airborne particles with a size of 0.3 microns (µm).
ULPA filters are capable of trapping smaller particles due to the dense filter material. Although this may seem like an advantage, ULPA filters allow up to 50% less air to pass, when compared with HEPA filters, resulting in fewer air changes per hour.
Classifications
Cleanrooms are classified by how pure the air is. Specifically, classifications are designed to categorize a cleanroom by the number of particles found in the lab’s air. The cleanroom classification standard ISO 14644-1 uses particular particle count measurements to categorize the cleanliness or air purity level of a clean zone or cleanroom.
Here’s some perspective.
Outside air in a metropolitan area has about 35,000,000 particles for each cubic meter within the range 0.5 μm (μm = micrometer) and bigger in measurement, which is the equivalent of an ISO 9 cleanroom. On the other end of the ISO spectrum, an ISO 1 cleanroom allows no particles in that range (0.5 μm and bigger in measurement), and only 12 particles for each cubic meter that is 0.3 μm and smaller.
Cleanrooms are categorized according to both the size and the number of particles present per volume of air. ISO 14644-1 standards specify the decimal logarithm of the number of particles 0.1 µm or larger present per cubic meter of air.
ISO 1 for instance, has at most 10 particles per m³ (cubic meter) and ISO class 4 cleanroom has at most 10,000 particles per m³.
AIR FILTRATION
Cleanrooms use filters to trap dust, airborne particles, and other contaminants before they enter the room. The most used filters are HEPA and ULPA.
US FED STD 209E cleanroom standards &
ISO 14644-1 cleanroom standards
The cleanliness of a cleanroom is defined by ISO-14664 standards. These standards, written by the International Organization for Standardization, were first derived from the US Federal Standard 209E Airborne Particulate Cleanliness in Cleanrooms and Clean Zones in 1999.
As of November 29th, 2001, the Federal Standard 209E has been replaced with ISO 14644-1. The number assigned to the class is the classification to which the room must be designed to. In the Fed. Standard 209E, Class 1 was the cleanest; the new ISO 14644-1 Standard, Class 3 is the cleanest. The federal standards were measured in cubic feet, and the ISO standards are measured in cubic meters.
Class 3, 4, and 5 ISO standards are based on the maximum number of 0.1 and 0.5 micron particles that are permitted in a cubic foot of air approaching any work operation within the room. Class 6, 7, and 8 are based on the number 0.5 micron particles. One micron is one-hundred the width of a human hair. The smallest particle seen with the naked eye is a 10 micron particle.
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