# Factory Pre-Testing and CFD Validation Delta builds and fully tests modular data centers in the factory before shipping. This isn't just a power-on check — it includes thermal simulation of the actual deployment conditions. **What happens in the factory:** 1. **Physical build** — racks, cooling, power distribution, cabling all assembled 2. **CFD (Computational Fluid Dynamics) modelling** — simulates airflow, hot spots, and cooling performance under site-specific conditions 3. **Altitude derate simulation** — for deployments like Nairobi (1,700m), the thermal model accounts for reduced air density per ASHRAE tables 4. **Full power-on testing** — the MDC runs under load before it ships **Why factory beats field:** - Problems found in a factory cost hours to fix. Problems found on-site cost weeks. - Factory conditions are controlled — you can instrument everything, repeat tests, isolate variables. - CFD validation catches thermal design errors before they become operational failures. - Total timeline: ~6 months factory build + 1 month shipping vs 12-18 months for traditional on-site construction. **The altitude angle:** If you're deploying at altitude (Nairobi, Denver, Mexico City), the factory must simulate those conditions. Sea-level testing will pass hardware that fails thermally at 1,700m because condensers reject 15-20% less heat in thinner air. The CFD model must use site-specific air density, not vendor defaults. **Key takeaway:** Factory pre-fabrication with site-specific thermal validation compresses timelines and eliminates an entire class of deployment failures. --- See also: [[PUE at Altitude — ASHRAE Derate]] | [[Transport Constraints as Design Inputs]] | [[Modular Data Centers MoC]]