A modular data center is complete in the factory but arrives on the pad as several boxes. The few dozen lines running between those boxes are the only part of the product assembled on site — which makes them the easiest thing to get wrong and the hardest to redo.
MDCX standardises them: coupling type, length margin, test method and acceptance criteria are all fixed. On site you plug things together. You do not crimp, you do not weld, and you do not drain a loop.
This page is the public summary of that standard. Product figures live in the claims registry; SKUs and solution codes are in the product matrix.
Three principles
1 · Water is always a double-shutoff dry-break coupling. When modules are separated for lifting, both halves close automatically — nothing drains, no air enters, and no loop has to be refilled and purged on site. This is what makes "the module can go back on the truck" true rather than aspirational.
2 · Power is always a circular connector, IP67. Terminal strips may not cross a module boundary. Every circuit that crosses is a finished plug-and-socket pair, made up in the factory.
3 · The fixed half lives on the top gallery module's deck plate. The free half travels with the hose or cable as one "connection section". When a box comes apart, what stays on the equipment is always the closed fixed half — there is never a live, pressurised free end hanging in the yard.
Connector classes
| Class | Form | Shutoff / contacts | Materials | Site action |
|---|---|---|---|---|
| Cold-plate loop (HT) | Double-shutoff dry-break | Both sides close | 316L / EPDM | Latch |
| In-row CW loop (LT) | Double-shutoff dry-break | Both sides close | 316L / EPDM | Latch |
| CDU primary side | Double-shutoff dry-break | Both sides close | 316L / EPDM | Latch |
| Fire main | Dry-break, normally open | One side closes | 304 / FKM | Claw + safety pin |
| Power circuits | Circular connector | 3P+N+PE | IP67, threaded lock | Torque to the witness mark |
| Control and signal | Shielded circular | — | IP67 | Thread on |
| Network | Pre-terminated MPO-12 APC | OS2 single-mode | IP67 circular shell | Push to click |
How lengths are set
Hose length is measured on the assembly model as a numerical integration of the cubic Bézier centreline — both ends normal to their faces, lateral offset absorbed by an S-bend. Cable length follows the orthogonal route from the tap-off gland to the equipment gland. The measured value then takes a margin:
L_order = ceil(L_measured × 1.15) hoses
L_order = ceil(L_measured + 0.3 m) cablesceil rounds up to the next 50 mm. After rounding, each class collapses to a handful of order lengths — which is why spares are stocked by class rather than by position.
Bend radius is checked at the worst case: hoses at least 4× DN, cables at least 12× D, fibre at least 20× D.
Type and routine tests
Type tests cover the first three pieces of each class; routine tests are 100%.
| Test | Method | Pass criterion |
|---|---|---|
| Hose assembly hydrostatic | 1.5× nominal pressure, 10 min (ISO 1402) | No leak, no permanent deformation |
| Hose burst (type) | Stepped to burst (ISO 1436) | At least 4× nominal pressure |
| Dry-break spillage (type) | Ten separations under pressure, spillage collected (ISO 18869) | 5 mL or less per event (15 mL for the large bore) |
| Coupling durability (type) | Cycled at rated pressure (ISO 18869) | Seals hold after 6 000 cycles |
| System tightness | 0.6 MPa dry nitrogen, 24 h | Pressure drop 1% or less |
| Cable insulation resistance | 1000 VDC megohmmeter (GB/T 3048) | 100 MΩ or more |
| Power-frequency withstand | 3.5 kV for 1 min (GB/T 16927) | No breakdown, no flashover |
| Connector contact resistance | Four-wire method (IEC 60512-2-1) | Increase of 0.5 mΩ or less |
| Connector durability (type) | Unloaded cycling (IEC 60512-9-1) | 500 cycles or more |
| Ingress protection | Immersion test (IEC 60529 IP67) | No ingress when mated |
| Optical link loss | Insertion and return loss (GB/T 50312) | IL 0.35 dB or less, RL 50 dB or more (APC) |
Site acceptance
Every item is checked after installation. Joint commissioning starts only once all of them pass and the sheet is signed.
| Item | Method | Criterion |
|---|---|---|
| Installed geometry | Total station / calipers, 20% sample | Fixed-half axis within 2 mm of the equipment port; no twist in the hose |
| Bend radius | Visual plus template, 100% | Meets the minima above |
| System pressure | 1.25× working pressure, 30 min | No leak, pressure drop 2% or less |
| Live disconnect demonstration | One set per class separated under pressure and remade | Spillage within limit, no leak after remaking |
| Electrical | Phase sequence, insulation, circuit volt drop | Sequence matches; insulation 100 MΩ or more; drop 1% or less |
| Locking | 100% | Coupling latch audible; connector ring aligned to its torque mark |
| Marking | 100% | Code, colour and flow arrow present and matching the as-built drawing |
| Interchangeability | Three sets swapped within a class | Mates freely; cannot be mated to a different circuit |
| Documentation | — | Material certificates, type-test reports, works test sheets, signed sheet |
Marking and interchangeability
- Coupling codes read
[system]-[equipment]-[function], with labels on the fixed-half flange and on both ends of the hose or cable. - Colours: HT supply orange / return red, LT supply cyan / return blue, primary side supply green / return brown, fire red, valves yellow.
- Couplings of the same bore on different circuits use different key angles; connectors use one key per circuit — misconnection is prevented mechanically, not by reading a label.
- Where units of different capacity sit on the same circuit, the equipment code must carry the model, and it must agree with the as-built drawing and the balancing-valve schedule.
- Hoses and cables are supplied as finished assemblies with both ends fitted. Nothing is crimped on site. Spares are held at 10% per class.
Relationship to the other standards
This standard governs the interface between modules. Piping inside a module, wiring inside an enclosure and the equipment itself follow their own product standards and the four capability axes. Mechanical and electrical boundaries that cross modules — busway interfaces and lifting points among them — are defined separately.