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16 BioPharm International ® Manufacturing and Facilities eBook 2023 www.biopharminternational.com Facilities: OligOnucleOtides high-hazard occupancies (H-occupancies) based on material hazard classifications and quantities. The IBC specifies maximum allowable quantities (MAQs) of hazardous materials that, if exceeded, trigger the requirement for an H-occupancy. Thresholds vary de- pending on material hazard classification, material use and storage, locations in facilities, and building occupancies. Classification is based on risks posed by materials to life, health or property related to ma- terial characteristics such as f lammability, toxicity, corrosivity, and reactivity. Control areas Control areas are those in which hazardous materi- als are used or stored at quantities below the MAQs. While H-classification can offer some f lexibility, that area classification requires additional design ele- ments and tend to cost more to construct and operate than a non-hazardous occupancy. Facility occupants and neighboring areas are protected from potential risks through the following design considerations. General design The number of control areas allowed in a facility is limited as a function of building f loor level. MAQs d rop con siderably for a rea s above or below t he ground f loor and, the number of control areas above and below ground level needs to be f ur t her con- strained due to code restrictions. Separation Control areas need to be separated from other areas of the building, including other control areas, by fire walls, fire barriers, or horizontal assemblies con- structed with fire-resistance ratings appropriate for the specific hazard. This depends on the hazardous material classifications, the potential risks they pose, and the f loor on which a control area is located. Ignition source control Electrical hazardous area classifications related to electrical componentry, proper grounding and bond- ing, and restrictions on open flames or sparks mitigate the risk of ignition sources where f lammable vapors or gases may be present. The criteria for determining grades and boundaries of these classifications are pri- marily found in NFPA 70: National Electrical Code (4) and NFPA 497: Recommended Practice for the Classi- fication of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Instal- lations in Chemical Process Areas (5). This typically drives a classification of Class I, Division 2 for most areas using and storing ignitables and even Class I, Di- vision 1 in some cases where open processing cannot be avoided. Open processes are also more limited in MAQs than closed processes. H-occupancies H-occupancies have more stringent design require- ments than control areas due to risks associated with use and storage of greater quantities of hazardous mate- rials. In addition to the requirements for control areas, H-occupancies have the following requirements. General design H-occupancies are divided into five classifications (H-1 to H-5). Oligonucleotide processing facilities are often restricted under H-2, H-3, or H-4: • H-2 classification is reserved for the presence of ignitables exceeding MAQs and operating in open processing or at pressures >15 psig in closed systems. • H-3 classification applies when the same ignitable materials are used in normally closed systems and at pressures <15 psig. • H-4 classification applies when materials with health hazards but no significant flammability hazards, including corrosives or toxics exceeding the MAQs. • Individual H-2 and H-3 areas that exceed 500 square- feet where open systems are used and 1000 square- feet where closed systems are used, must have at least 25% of their perimeter on an exterior wall. Construction H-occupancies t ypically require higher fire-resis- tance ratings than control areas for building compo- nents, including fire walls, fire barriers, horizontal assemblies, and protection of structural members. This translates to more robust construction require- ments for and around these components and varies between different classifications of H-occupancies. Separation B u i l d i n g s c on t a i n i n g H- o c c up a n c ie s mu s t b e set back f rom proper t y l i nes a nd publ ic ways as prescribed by code. BPebook1123_Facilities_Olgonucleotide_CRB *All figures courtesy of the author* Figure 1: Hazard classification of chemicals typically used in oligo production. Figure 2: Base Case: Typical raw material and waste collection scheme. FIGURE 1. Hazard classification of chemicals typically used in oligo production. FIGURES COURTESY OF THE AUTHORS.