Frequently Asked Questions About cleanrooms

Cleanroom FAQ

It's a room in which the number of particles in the air is controlled and kept within specific limits as defined by Federal Standard 209E. These rooms might be used to make microchips or to study space dust (such as the NASA Genesis Project Cleanroom), anywhere airborne particulate contamination must be controlled and kept below a certain level.

Simply, it's an official document that outlines the classes of air cleanliness.

Read it here (PDF)

Cleanroom cleanliness is measured by how many micron sized particles pass through one cubic foot of air per minute (cfm). This is how a cleanroom's classification is determined.

A Class 10 cleanroom has no more than ten micron sized particles passing through each cubic foot of air per minute. That's really clean. A Class 100,000 may have up to one hundred thousand particles per cubic foot. For comparison, your home has around 300,000 and a hospital operating room has about 1,000.

A micron is a millionth of a meter. Tiny, even compared to a human hair which is about 100 microns.

Most particulate contamination comes from people. We are shedding particulate matter every minute, even by breathing.

In several ways. Cleanroom technicians wear special clothing that's designed not to shed or let particles escape. Often before entering the cleanroom, personnel will walk through an airshower which blows off any particles using high velocity air. And, in the cleanroom, places where dust could settle like ledges and moldings are minimized. We also create an airflow pattern called laminar flow that constantly cleans the air by directing and re-circulating it through special filters.

It's when all of the air in a cleanroom is forced to move in the same direction and speed to a filter. One common example of laminar flow is when the air moves from the ceiling through the floor, is forced up through the walls to be filtered above the ceiling and then reenters the room and continues the cycle.

High Efficiency Particulate Air. These replaceable filters will catch almost 100% of particles as small as .3 microns. You might find them in your own home or office as part of an air conditioner filtering system or a vacuum filter.

Ultra Low Penetration Air. These filters can remove almost 100% of particles as small as .1 micron from circulating air.

It's a hallway or room leading to the entrance of the cleanroom. Often there is an airshower between the dressing room or gowning area and the main entrance to the cleanroom. In the airshower, high velocity air blows off debris that could contaminate the cleanroom environment. Sometimes de-ionizers are used to remove static thereby increasing the effectiveness of removing hair and lint. Learn more by examining Lasco's airshower.

A pass-through (pass-thru) is a chamber that allows items to be moved between cleanrooms or between cleanroom and non-cleanroom areas. Less traffic in and out of the cleanroom means fewer chances for contaminants to enter. Pass-throughs can also be designed so that only one door will open at a time. This, in conjunction with higher air pressure inside the cleanroom, forces particles out when the inner door opens. View some examples of Lasco's pass-throughs.

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