Cleanrooms, or environmental control areas (ECAs), are spaces that are designed to keep out as much dust and other contaminants as possible.
The most common type of contamination that can enter a cleanroom is human generated particulate contamination. For this reason, at Precision Fabricating and Cleaning (PFC), we’ve set up basic procedures for our personnel to follow when they enter a cleanroom. These procedures ensure that the cleanroom stays “clean” and free of foreign particles.
Following these procedures comes with a second benefit: they help us protect the tests, research, and other projects occurring within the cleanroom from becoming ruined by invasive particulate matter.
Below, we define human generated particulate contamination, as well as outline the proper procedures for cleanroom entry that are designed to prevent this type of contamination from entering and spreading within an ECA.
Human generated particulate contamination occurs when a space becomes contaminated with the particulates that human beings naturally generate.
In a cleanroom, an adult who is fully gowned in cleanroom attire will generate 100,000 particles per minute when motionless, and 1,000,000 particles per minute when walking. The more active a person becomes in the room, the more particles they generate.
Even the speed at which a person walks through a cleanroom can triple the number of particles they emit. They can also change the dynamics of the room by traveling faster than the room’s natural flow of air.
To reduce the amount of human generated particulates entering our cleanrooms at PFC, we adhere to a series of technical procedures for ECAs.
We follow eight basic procedures for cleanroom entry at PFC.
1. Number Of Allowed Personnel In Cleanroom
The number of personnel allowed in the cleanroom is based on 2 people per 100 square feet. The total number of personnel allowed in PFC’s cleanroom at any one time is limited to 34.
2. Personnel Attire
Personnel within an ECA at PFC must wear static resistant uniforms consisting of a full body jumpsuit, shoe covers, gloves, and full head covers. The head covers come with a face-hood or eye-hood to provide coverage of the entire head and neck.
Eye-hood covers are required for anyone who has any type of facial hair, allergies, a cold or the flu, or a skin and/or hair shedding problem (even if controlled by medication).
Clean room clothing shall not be opened (i.e., unsnapped or unzipped) in the cleanroom or exposed to any environment outside the ECA, with the exception of the personnel airlock.
Street garments (i.e., jackets and sweaters) shall not be located on the same rack or in the same locker as clean room garments.
3. At Home Preparation
Cleanroom entry procedures aren’t limited to the PFC facilities. They actually begin at home.
Here are some at-home preparations that PFC personnel are required to adhere to if they’re going to enter a cleanroom later in the day.
- Brush teeth
- Brush hair
- Wear proper attire
- Practice good personal hygiene
- Select non-shedding undergarments
- Select non-shedding over garments
Before they can begin the gowning procedure at work, personnel must perform these pre-gowning steps.
- Store all outer garments and personal belongings separately and securely
- Remove all non-approved jewelry and store them
- Remove all cosmetics
- Wash and dry hands
5. Cleanroom Garment Inspection
Next, personnel entering the clean room must visually check the condition of their uniform prior to entry. Uniforms which are torn, fraying, or that have defective zippers must be discarded and withheld from use.
At no time while they are in the cleanroom should personnel unzip, open, or remove their clothes.
6. Gowning Procedure
Finally, after following the previous five steps, personnel can begin the gowning procedure and prepare for entry to the cleanroom.
Gowning is the process of wearing special garments to control particulate contamination within an ECA.
Correct gowning procedures are extremely important. One of the problems with particulate contamination is that it is mostly invisible to the naked eye. Any contamination introduced to the cleanroom on the outer surface of clothing will go unnoticed. This means that a breakdown in correct gowning procedures will be immediately apparent.
In accordance with the gowning procedure, personnel must be restricted from:
- Wearing nail polish or false fingernails
- Wearing jewelry, wristwatches, and other types of decorative accessories
- Cosmetics, hair spray, perfumes
- Carrying mobile devices
Below are the specific steps for completing the gowning procedure.
- Clean shoes with shoe brush
- Step several times on Tacky Mat in the entryway
- Don disposable booties
- Don hair net
- Don face hood or eye hood
- Don coverall
- Don cleanroom booties
- Don cleanroom gloves
- Walk over Tacky Mat
7. Removal Of Cleanroom Garments
After leaving the cleanroom, personnel must remove their cleanroom garments.
Personnel must remove their cleanroom garments in the reverse order that they put them on. The disposable shoe covers must not be removed until the person is at the clean/dirty line, at which point they must be removed one at a time. At no time should an unprotected shoe be placed on the clean side.
Cleanroom garments are segregated for re-cleaning when visually contaminated or at least every 3 days. These items must not be used before being re-cleaned. Disposable gloves and shoe covers must be discarded when personnel exit the cleanroom.
As you can see by our rigorous procedures for maintaining contaminant-free cleanroom entry, we take cleanroom safety and the integrity of the testing that happens inside it seriously. To work with PFC, contact us here.