Clean Room Classification

What is Cleanroom?

A cleanroom has a controlled level of contamination that is specified by the number of particles per cubic meter at a specified particle size.

Particle counting is done in two ways:

1. Non-Viable Particle count (NVPC)
2. Viable Particle Count

Non-Viable Particle count (NVPC)

    

 At Rest: A cleanroom that is complete and ready for operation with all servicing functioning and with equipment installed and operable as specified but without operating personal in the facility.

At Operation: A cleanroom is normal operation with all services functioning and with equipment and personal and performing their normal work function in the facility.

Q: Why we consider only 0.5µ and 5µ particles?

A: Size less then 0.5µ is not very critical because microbes are less likely to attach to this size of the particle and greater than 5µ particle becomes heavy as the size of these particles increases and can be easily settled down.

Viable Particle Count

CFU= Colony Forming Unit

 Air sampling is done by two methods

1. Active air Sampling: A microbial air sampler is used to continuously force an already established volume of air to pass over petri dish that serves as the artificial medium containing an agar nutrient-based test media.
2. Passive air sampling: It involves leaving settle plates exposed to the air for a certain period to collect microbes that may settle onto the supplies of plates.

Q. Why we expose media plates for 4 hours in the cleanroom?

A. After 4 hours, the agar forms a skin layer on it which reduces the access of water to microorganisms thus reducing their growth.

Also, media plates start losing their weight as soon as they are put into action. after 4 hours they have undergone their maximum weight loss and should not be used for further examination.