FAQ

Common questions about EarthLedger liquid cooling quick disconnects (UQD/UQDB), OCP compatibility, and interchangeability with Danfoss/Stäubli. For anything not covered, contact +86-189-2679-5526 or admin@earthledger.com.

Q1. What's the difference between UQD and UQDB? Which one should I choose?

UQD is a manual quick disconnect — for visible, hand-operated connections such as outside-rack and modular liquid cooling units.

UQDB is a blind-mate quick disconnect — designed for in-rack, high-density servers. Server insertion auto-mates the coupling without manual handling. Compliant with OCP ORv3 BMQC spec, with 5 mm radial + 2.74° angular misalignment tolerance. Suitable for GPU servers (H100, 5090, 4090D clusters).

Selection guide: in-rack, high-density, fast service → UQDB; outside-rack, main pipe, CDU connection, manual → UQD; unsure → contact us with your server model and rack depth, we'll recommend.

Q2. Are they compatible with Danfoss UQD03 and Stäubli CPC LQ?

Yes. Our UQD/UQDB series is built strictly to OCP BMQC spec, mechanically and hydraulically interoperable with Danfoss UQD03, Stäubli CPC LQ, CEJN, and other OCP-compliant brands — direct plug-in interchangeable.

Use case: existing Danfoss/Stäubli installations can add our products on the new server or cold plate side without replacing the full set.

Q3. Working pressure, flow rate, temperature range?

All per OCP BMQC Draft May 2024. Our products pass pressure-drop validation at every test point (2/4/6/9/10 LPM).

Parameter	Value
Max Working Pressure	50 PSIG (3.45 bar)
Hydrostatic Test (3×)	150 PSIG × 3 min
Max Flow Rate	9 LPM
Operating Temp (with fluid)	-5°C ~ 60°C
Non-operating Temp	-40°C ~ 70°C
Operating Humidity	10% ~ 93% RH (non-condensing)
Test Fluid	Dowfrost LC25 (25% propylene glycol) / pure water

Q4. Why mandatory EPDM seal material?

EPDM (ethylene propylene diene monomer). OCP BMQC mandates this material because: resistant to propylene/ethylene glycol corrosion; long-term 60°C fluid resistance; ozone aging resistance; doesn't embrittle under prolonged cycling (unlike NBR).

Do NOT use NBR seals (designed for oil-based fluids — swells and deforms in glycol).

Q5. Cycle life rating?

Per OCP BMQC life testing: Wet test 120 cycles (40 aligned + 40 radial 5mm offset + 40 combined), at two speeds (0.038 m/s and 0.31 m/s); Dry test 36 cycles (12 aligned + 12 radial + 12 combined); Spillage cumulative: @50 PSIG ≤ 0.05 cm³/cycle, no leakage over full life.

In real-world deployment with 2-4 maintenance disconnects per year, 10-20 year life is straightforward.

Q6. How many UQDBs per GPU server? Where does the ORv3 24-valve number come from?

Per OCP ORv3 Manifold Base reference design: 12 valves per side, 24 valves total (left 12 return / right 12 supply, viewed from rack rear).

Each 1OU server pairs with one inlet+outlet, so 24 valves serve 12 server units. For GPU servers: 4-8 GPU single-card cold plate + 1 UQDB pair → 1 rack slot; 8 GPU full water cooling + 2 UQDB pairs (redundant) → 2 rack slots.

For non-ORv3 racks, send us depth (OU count) and GPU config — we'll provide a selection plan.

Q7. Does your software monitor leaks? How does it integrate with BMC / DCIM?

Yes. Our intelligent liquid cooling power management software supports: three-tier leak detection (Indirect leak rope/conductivity → Direct fiber/ultrasonic → Auto Intervention auto valve close); protocols: Modbus input → DMTF Redfish output (compatible with mainstream BMCs like ASPEED AST2600); DCIM integration: Redfish JSON push to Schneider EcoStruxure / Vertiv Trellis / custom DCIM; maintenance scheduling: based on cycle count + EPDM aging prediction, 30-day advance replacement reminder.

Sensor placement: external to manifold / port tee — not inside the BMQC flow path. This avoids disturbing OCP §9.8.1 pressure drop curves and §9.4.1 mate forces.

Q8. Test reports / compliance? OCP test white papers?

We provide: OCP BMQC 4-pack test report (pressure drop curves / Spillage / Hydrostatic / Wet life 120 cycles); materials list (wetted parts SS303/304/316, EPDM seals, full RoHS 2015/863/EU); environmental compliance: REACH (incl. PFAS declaration), WEEE 2012/19/EU, EPA 40 CFR75; test white paper: UQDB series in progress (expected 2026 Q3), will be downloadable from website.

Contact sales for current test reports.

Q9. Lead time? Stock vs build-to-order?

Stock: common SKUs (UQD-04, UQD-06, UQDB-04, UQDB-06, UQDB-08) ship in 3-7 days.

Custom: special threads (G1/8, G5/8) or custom color bands / seals → 25-35 days.

Bulk (>500 sets): negotiate separately.

We've expanded common-SKU stock based on past lost-deal data. Confirm inventory before ordering.

Q10. Domestic vs imported brands — main differences?

Dimension	EarthLedger UQD/UQDB	Imported (Danfoss UQD03 / Stäubli CPC LQ)
Mechanical/hydraulic interface	OCP BMQC, interchangeable	OCP BMQC, interchangeable
Performance (drop/spillage/life)	Per OCP spec, fully tested	Per OCP spec
Price	Domestic	Imported (incl. tariff & shipping)
Stock lead time	3-7 days	4-12 weeks
Custom response	25-35 days	12-20 weeks
After-sales / RMA	Direct domestic	Via agent / cross-border
Test reports	OCP white paper (2026 Q3)	Available

Q11. How do I get CAD models?

CAD library is in development — expected 2026 Q3 launch. Will offer: STEP / IGES / Solidworks parts; online selector (recommend SKU by rack depth, GPU config, flow requirement); drag-and-drop ready parts with preset parameters.

In the meantime, contact sales for STEP files.

Q12. After-sales / RMA process?

24-hour phone response: +86-189-2679-5526; 48-hour onsite support commitment (within South China); free replacement for non-human-caused failure within life cycle (120 wet cycles); onsite service + remote diagnostics (via our power management software remote logging).