Primary HEPA filters

The primary factor in filter replacement is pressure drop. Typically, HEPA filters are replaced when the pressure drop exceeds 100 mm WG. By specification, FIEPA filters must have sufficient structural pressure to withstand a continuously applied overpressure of 250 mm WG or higher for at least 15 minutes without visible damage or loss of efficiency. 

Primary collector An air-cleaning device that removes the larger particulate matter before a HEPA filter. 

Conventional airflow (also known as turbulent, or non-unidirectional airflow) incorporates HEPA filters, located in-duct, or as room terminal filtration modules (TPMs Fig. 5). Often confused with LAP, conventional airflow does not meet that definition because it allows multiple-pass circulating characteristics or a non-parallel airflow direction, or both. This type of airflow is incapable of producing first air, and is normally used as secondary or buffer filtration in treating a processing or compounding space that contains laminar airflow devices (LAFDs) to maintain primary critical work surface conditions, or in treating other... 

A room cleanliness classification is a critical parameter and, therefore, the room air change rates and HEPA filters should be critical parameters and require qualification. Items such as the fan generating the airflow and the primary and secondaiy filters are non-critical parameters, and may not require operational qualification. 

A Processing Tank Containing Cell-Free Supernatant Aseptic Sample Port 9 C Cabinet (negative p ssur Primary and HEPA Filters 14... 

Primary confinement provided by Process Extraction SCB s and Zone 1 exhaust ducting from the SCBs up to the HEPA filters at the HCF Stack,... 

Ventilation Hot Exhaust (Zones 1 and 2A combined exhaust) Control of off-site radioactive material releases. 1. Hot exhaust confinement boundary integrity must not be compromised by ventilation system fan mis-operation or malfunction. 2. HCF operators must maintain the required functional performance of confinement controls. 3. HCF operators must verify the functional performance of the hot exhaust HEPA filters. 1. A ventilation system fan sequencing interlock ensures that the backup exhaust fan is automatically started upon loss of the primary operating fan. An aiann alerts the operations staff upon loss of the operating stack exhaust fan. 2. Administrative controls are in place to ensure periodic ventilation system fan sequencing interlock testing. 3. Administrative controls are in place to ensure periodic functional performance and efficiency testing of the HEPA filters. 

FIGURE 7.3.4.1 Components of a HEPA Filter, (a) Borosilicate glass woven filter with aluminum separators (small folds) and (b) HEPA filter mounted in a wooden box. (From Figure 1 in CDC/NIH, Primary Containment for Biohazards Selection, Installation, and use of Biological Scfety Cabinets, 3 edition, 2007 available at http //www.cdc. gov/od/ohs/biosfty/primary containment for biohazards.pdf.)... 

Exhaust air from primary containment devices (fume hoods, safety cabinets or other) shall be appropriately treated by filtration using a high efficiency particulate air filter (HEPA), or by adsorption, absorption, reaction, incineration, or dilution used individually or in an appropriate combination. If HEPA or charcoal filters are used, these must be installed and operated to permit decontamination, maintenance, and replacement without exposing personnel or causing contamination of the environment. 

The liver is a vital organ in the body that plays a primary role in the digestive system in detoxification, protein synthesis, and filtering of blood [56]. Liver-on-a-chip platforms have been developed to understand liver function better and to study drug hepatotoxicity and metabolism [29, 57, 58]. A microfluidic-based device fabricated to mimic the permeable sinusoid endothelial barrier between hepa-tocytes and liver [29] includes three main sections—a central channel to pack the hepatocytes, a microfluidic sinusoid barrier consisting of a set of narrow (2 mm wide) microchannels to model the endothelial barrier, and a convection microfluidic channel surrounding the barrier (Fig. 5A). The flow of nutrients through the convection microfluidic channel feeds the hepatocytes. This system mimics the transportation between blood flow and hepatocytes, and the shear stress over hepatocytes with a patterned set of microchannels. 

Camfil Farr Air Pollution Control (APC) now offers its Gold Series cartridge dust collector with an optional integrated HEPA safety monitoring filter. Mounted on top of the collector so no additional floor space is required, this after-filter prevents collected dust from re-entering the workspace if there s a leak in the primary filtering system. Camfil Farr, www. farrapc.com, (800) 479-6801. Circle 251... 

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