PAN-FSR-2091-053

Fault Description

No fault. This FSR was auto-generated by the facilities preventive-maintenance scheduler when chiller CV-2 reached its semi-annual service date. The Cryo Subject Vault operates on a redundant chiller pair (CV-1 and CV-2) maintaining the vault at −196°C (liquid-nitrogen-backed) with the chillers providing pre-cooling for the LN₂ recirculation loop and maintaining the vault antechamber at −80°C. SOP PAN-ENG-041 (Cryo Vault Chiller Service) mandates semi-annual inspection of each chiller unit. CV-1 was serviced in Q1 2091 (PAN-FSR-2091-014). This FSR covers CV-2. The Tier 2 classification reflects the Cryo Vault's BCL-3 designation — the vault contains the Directorate's banked subject-line genetic material, engineered cell lines, and iPSC progenitor stocks. A chiller failure that compromised vault temperature would risk irreplaceable biological assets.

Root Cause Analysis

Not applicable — scheduled preventive maintenance. No corrective action required to date. Oil-analysis results (see Work Performed, step 2) are pending and may indicate a need for compressor-oil replacement if contamination levels exceed threshold.

Work Performed

A. Reyes and N. Chandra attended Sub-level B3 (Cryo Vault plant room) on 2091-05-20 at 05:00 local, during the vault's low-activity window. CV-1 remained online as the primary chiller throughout the service. Work performed under SOP PAN-ENG-041:

1. Refrigerant charge verification. System pressure checked at the high-side and low-side service ports. High-side: 18.4 bar (specification: 17.5–19.0 bar). Low-side: 3.1 bar (specification: 2.8–3.4 bar). Charge level within tolerance; no top-up required. Leak detection (electronic sniffer and UV dye inspection) performed on all brazed joints, service valves, and the compressor shaft seal — no leaks detected.

2. Compressor oil sample. A 50ml oil sample drawn from the compressor sump via the sampling valve. Sample logged as PAN-OIL-2091-CV2-Q2 and submitted to the external analysis laboratory (Intertek Singapore) for acid number, moisture content, wear-metal analysis, and viscosity testing. Results expected within 10 business days. This is the step holding the FSR open — the report cannot be closed until the oil analysis confirms the compressor oil remains within specification or a replacement is performed.

3. Condenser cleaning. The air-cooled condenser coil was cleaned with compressed air and a non-corrosive coil cleaner. Pre-cleaning condenser approach temperature: 8.2°C. Post-cleaning: 5.9°C (specification: ≤6.5°C). The improvement indicates moderate dust and particulate accumulation since the last cleaning — consistent with the sub-level's filtered but recirculated air supply.

4. Evaporator inspection. Evaporator coil inspected for frost distribution uniformity and fin damage. Frost pattern even across the coil face; no fin deformation or corrosion detected. Defrost cycle triggered manually and confirmed to complete within the 12-minute specification window. Post-defrost drain verified clear.

5. Control-system calibration. Temperature sensors (PT100, 4-wire) at the evaporator outlet, condenser inlet, and vault antechamber reference point verified against a NIST-traceable reference thermometer. Maximum observed deviation: 0.08°C (specification: ±0.15°C). No adjustment required. Compressor-staging logic verified: CV-2 confirmed to start within 15 seconds of a CV-1 high-discharge-temperature alarm, consistent with the redundancy specification.

6. Return to standby. CV-2 returned to hot-standby mode at 09:30 local. Confirmed operational by triggering a manual switchover — CV-2 assumed the primary load within 12 seconds; CV-1 transitioned to standby cleanly. Both units confirmed operational; system returned to normal CV-1-primary configuration.

Parts Consumed

1x compressor oil sample kit (P/N FAC-OIL-KIT-50) — consumed during oil sampling. Kit is single-use.

Coil cleaner, 500ml (P/N FAC-CC-NCA) — consumed during condenser cleaning. Drawn from facilities stores.

Sign-off Chain

Service performed by: A. Reyes, HVAC/Refrigeration Technician & N. Chandra, Facilities Engineer — 2091-05-20

Pending: Oil-analysis results review and close-out sign-off by N. Chandra, Facilities Engineer

Pending: Final report closure by M. Torres, Duty Engineer

Post-Action Notes

All physical service tasks completed satisfactorily. CV-2 performance metrics (discharge pressure, suction pressure, approach temperatures, staging response time) are consistent with the Q1 service results from the companion unit CV-1. The FSR remains open solely pending the external oil-analysis report. If the oil analysis returns within specification, the FSR will be closed with no further action. If acid number or moisture levels exceed threshold, the compressor oil will be drained and replaced — a procedure that requires approximately 4 hours and a second CV-1/CV-2 switchover. The Cryo Vault's biological assets are not at risk during this waiting period; CV-1 is fully operational as the primary chiller, and CV-2 has been confirmed functional in hot standby.