About T Squared
An independent company, with our contracting activities as our core business, we are focussed on deriving and delivering innovative ways of working.
Our keenly honed short lines of decision-making enable fast introduction of any change in the ways we operate which we believe will produce benefits to customers and staff alike.
Our personnel are carefully selected to ensure their characteristics can follow through our belief that each and every person needs to be the best they can be.
From Laboratory and Cleanroom Design to Build, and Management to Maintenance, we can take care of as much or as little of the project as you require.
What is Clean Air?
In Cleanrooms the particles that are being assessed are those which are larger than 0.5 microns. By example an average human hair is 100 microns thick. In a cubic foot of everyday air there will be ~ 1,000,000 particles above 0.5 microns mostly quite invisible. Cleanrooms are classified by the amount of such sized particles that exist in the room with a "medium" grade Cleanroom having to have fewer than 1,000 particles per cubic foot.
To get down to low levels of contamination Cleanrooms are generally controlled with a positive pressure to exclude dirty air infiltration and they are supplied with .Clean. air from air handling systems that feature HEPA of ULPA filters that can filter out particles which are 200,000 times smaller than the average human hair. By varying the air change rates of this Clean air the classification of the Cleanroom can be controlled at the levels required.
Cleanroom Classifications
Cleanroom is a bit of misnomer as some Cleanrooms are not that clean but the environment is controlled. Controlled Room might be a more accurate description but like it or not Cleanrooms is the description which is here to stay.
Most Cleanroom classifications stem from the original United States Federal Standard 209 which sets out from Class100,000 down to Class 1 the numbers being the number of 0.5 micron particles allowed in a cubic foot within the Cleanroom zone. In Europe a different version of this exists in ISO 14644-1 which has nine classifications - Class 1 to Class 9 with Class 1 being the cleanest.
In the production of Sterile Pharmaceuticals different standards apply and these take into account the condition of the Cleanroom. There are three conditions to consider: -
- As built - no equipment or personnel in the Cleanroom
- At rest - equipment installed but not running and no personnel present
- Operational - personnel present and equipment running
In the Pharmaceutical industry it became apparent ~ 50 years ago that regulation was required and this led to the release of the Guides to Good Manufacturing Practice (GGMP). The aim of these guides was to ensure that drugs were manufactured to the correct quality assurance levels. For microbial monitoring in the manufacture of sterile products the EU GMP Guide sets out levels of cleanliness that need to be achieved "at rest" and "in operation". There are four grades involved here Grade A being the most onerous where laminar flow workstations are essential down to Grade D the least onerous which is equivalent to a Class 100,000 or ISO Class 8 Cleanroom. These grades set out different targets for particle counts under the two different conditions. The current guidelines "Rules and Guidelines for Pharmaceutical Manufacturers and Distributors" was released in 2007.
These guides take into account that no two Cleanroom situations are the same and much is left to the designer to come up with the most efficient design that will allow the final Cleanroom installation to comply with the guidelines. Cleanrooms that operate to current Good Manufacturing Procedures (cGMP) are inspected on a regular basis by the MHRA for European operations or the FDA for United States operations.
Containment
In Cleanrooms containment can mean a lot of different things. In terms of particle control special Cleanroom clothing is used to contain the release of particles from the operators.
In Pharmaceutical Cleanrooms where powders are in use powder containment booths are used to protect the operators from the product with the use of specially ventilated benches and laminar airflow systems keeping personnel and powder particles apart.
Where toxic or pathogenic materials are involved in any process the operators are at serious risk so containment here is critical. In Cleanrooms and Specialist Laboratories where risks exist Safety Cabinets are used to protect the operator from the process. Safety Cabinets are classified as Class I, Class II or Class III depending upon the degree of risk involved. These safety cabinets are similar in appearance to laminar flow booths but have twin airflows so that dangerous fumes are exhausted through HEPA filters while Clean safe air flows into the replace this between the operator and the source of the emission.
Laboratory hazards are rated on a scale of as follows: -
Category 1 - normal laboratory situations
Category 2 - some risk to the operators but not something that could spread outside of the laboratory
Category 3 - serious risks that would not only involve the operators but could spread outside of the lab but the disease involved would have a known cure - here there will be safety cabinets with exhaust stacks and the room pressures controlled to provide a negative pressure regime at all times
Category 4 - this is the ultimate risk where the process is dealing with a hazard for which there is no known cure available - here humans and the microorganisms are kept totally separate using every possible method including special isolators, air suits and specially designed ventilation systems