A contained HPAPI cone mill is a fully enclosed conical impeller-screen size reduction system achieving operator exposure below 1 µg/m³ (OEB 5) during all operations — charging, milling, screen change, and discharge — through split butterfly valve (SBV) or rapid transfer port (RTP) inlet/outlet connections, HEPA-filtered negative pressure housing (−30 to −50 Pa differential), and glove-port screen access. Processing 5–4,000 kg/h with screen apertures of 0.5–8 mm across pilot to large-production scales, it delivers the same particle size performance as a standard cone mill while maintaining validated OEB 3–5 containment at every step of every batch throughout the campaign.

Powder is charged into the cone mill housing through a closed SBV or RTP connection — the inlet valve opens only after the charging vessel is docked and a positive mechanical interlock confirms zero open gap. The housing is maintained at −30 to −50 Pa relative to the surrounding room by a local exhaust ventilation (LEV) system with HEPA filter — any minor seal imperfection draws air inward rather than allowing product to escape outward. The conical impeller rotates (25–3,000 RPM, VFD) forcing product through the conical screen; sized product discharges through a second SBV or RTP connection directly into a contained receiving vessel below. Screen change and impeller access are performed through integrated glove ports without breaking containment — pressure-tested gauntlet gloves are integrity-tested before every shift. All operations are logged by PLC for 21 CFR Part 11 electronic batch record compliance.