Contamination sources that find their way into your cleanroom can be broadly classified into two categories. Those originating from the physical plant and those from processes/human actions.
The first category includes the HVAC design, including the cleanroom components like flooring, wall, and ceiling materials, as well as tool installation and venting.
The second more variable category comprises human actions taken to maintain mechanical systems. Specifically, it means those actions required to maintain mechanical systems, process controls, and cleaning and housekeeping protocols and measurements. It also includes the selection of support materials like gowns, gloves, wipes and shoe covers and operators.
The biggest variable is your operators. Don’t forget your cleaning and housekeeping personnel.
Thoroughly cleaning your cleanroom floors should be part of your overall cleaning protocol. And acceptable particulate and bacterial/microbial counts should be part of your cleaning protocol.
Develop a daily and weekly cleaning schedule. And determine who will take of this, when, and how frequently measurements will be taken.
Steps for Cleaning a Cleanroom Floor
- Vacuum the surface.
- Wash floor with a 16:1 solution of deionized water and floor cleanser using a clean, non- contaminating mop head,
- Rinse with deionized water and a new, clean non-particulating mop head,
- Leave rinse water on the floor long enough to completely saturate any film build-up,
- Mop up rinse water using a lint-free cleanroom mop, changing the water after mopping every 10 to 15 square feet of floor surface.
- Change water regularly to minimize the risk of cross contamination due to dragging contamination from one area of the cleanroom floor to the next.
- Re-vacuum the cleaned floor once it is dry.
Cleanroom Classification & Maximum 0.5 Contaminant Levels
Various ISO classes determine acceptable contamination levels as follows:
- ISO 03 (Class 1): Max 1 particle/cubic foot of air;
- ISO 05 (Class 100): Max 100 particles/cubic foot of air;
- ISO 06 (Class 1,000): Max 1,000 particles/cubic foot of air;
- ISO 07 (Class 10,000): Max 10,000 particles/cubic foot of air.
Many industries must control to smaller particles than 0.5 microns. They may also control for bacterial and other microbial components. Contamination of a cleanroom is expensive when it causes products to be scrapped, research to be done over, or expensive equipment to fail.