Loop · docking · manifold planning
Design Guides — Loop, Docking and Manifold Planning
Four decisions that get frozen before the first drawing is released. Here are the numbers we would check.
Request spec sheetRead the number, then check it against your stack-up.
Starts from 3× the hose length, and from whether the socket is on a reinforced panel. per the OCP UQD specification
Starts from a plug 18 mm wide on a preferred 20 mm pitch, and from the force you are asking a latch to hold. per the OCP UQDB specification
Starts from the rack standard: 42U, 48U or 52U, each with its own manifold length. industry practice
Starts from ±5% branch uniformity and a header that stays at or under 2 m/s. industry practice
Two further worksheets sit below them: size class and tolerance stack.
Size class
Four panel-mount sizes · one blind-mate class
This is the decision every other number is read against: a bore is chosen once, and the loop diagram, the port pitch and the flow balance are written after it.
The five thumbs are for shape comparison at a common scale, not for gauging — the derivation is in the choosing-a-size note.
Service loop
Panel mount · loop length · clamp points
Panel, socket, loop and the two leaders a layout has to carry: the loop's own length and the distance from the socket to where the hose is first clamped.
Panel mount
Sockets are mounted through the panel with a reinforcement plate, so the mechanical stress of a connect goes into the panel rather than into the hose. per the OCP UQD specification
Loop length
A service loop of about 3× the hose length is the figure to lay out against. It is the allowance that lets a tray slide without loading the coupling. per the OCP UQD specification
Worksheet
Loop sag and clamp points are listed in the worksheet, so the loop is drawn once and clamped once instead of being re-routed on site.
Action
Check the loop against the door swing and the cable tray before the drawing is released, not on site.
Both images above are renderings produced for this site. What the panel socket is mounted into — the tray and the backplane — is on the UQD page.
Docking envelope and port pitch
Body width · pitch · engagement and extraction force
Six ports on one pitch. The upper leader is the pitch itself; the lower one is the row length it produces.
Body width
Plug width is 18 mm or less, which is the constraint the tray cut-out is drawn against. per the OCP UQDB specification
Preferred pitch
20 mm between ports. Lay the pitch out first and let the port count follow it, rather than fixing a count and discovering the pitch will not fit. per the OCP UQDB specification
Forces
12–30 lbf to engage, 10–35 lbf to extract. Check the extraction figure against the latch you have chosen before the layout is frozen. recommended values, per the OCP UQDB specification
Action
Adjacent-port clearance is checked before the tray layout is frozen. Trays are cheaper to change than tooling, and this is the last point at which changing one costs nothing.
The pitch is what the float is spent on: the wider the pitch, the more misalignment the tray has to absorb before the pins take the load. Envelope figures: the blind-mate page.
Tolerance stack
Where the allowance goes · what a shim does
Spend it once
A stack-up is a budget: panel position, plate thickness, socket seating and tray height all draw on the same allowance. Deciding them in that order is what keeps the float in reserve for the tray that actually arrives.
Action
Send the stack-up with the elevation before the layout is frozen, and the drawn figures come back marked against it. On a full rollout that mark-up opens a file — see project support. The long derivation of the same budget is the blind-mate tolerance note.
Shim stack · renderings, not photographs
Rack height
42U · 48U · 52U · clearances
Three rack standards on one ladder: the step height is the manifold length, and the dashed rules are the clearances that have to be re-stated in the same revision.
42U
Roughly 1800–1900 mm of manifold. industry practice
48U
About 2100 mm. industry practice
52U
More than 2400 mm, and at this height the ceiling is part of the drawing. industry practice
Action
Fix the rack standard first. Ceiling and cable-tray clearances are flagged on the height worksheet in the same revision as the manifold drawing, not in a second one issued later.
The manifold itself — port count, flow pattern and mounting position — is on the manifold page.
Flow balance
Uniformity · header velocity · the off-design check
A header with seven take-offs. The band above it is the ±5% allowance, and the marked edge is where a branch crosses out of it.
Uniformity
Target ±5% between branches, with an acceptance window of ±5 to 10% depending on the loop. industry practice
Header velocity
Keep the header at or under 2 m/s, so the take-offs see pressure rather than momentum. industry practice
Sizing rule
About 1.5 L/min per kW of heat load, used as a first pass before the loop is modelled. industry practice
Action
Check the balance at the design flow point and then again off-design. A loop that is even at 100% is often uneven at 40%, and the off-design case is the one a maintenance window produces.
Simulation and validation
CFD deviation · proof test · how the model is closed
CFD deviation
Benchmark makers publish a CFD deviation of ±3–5% against measured data. Use it as the error bar on any simulated figure before it is used to freeze a layout. industry-published benchmark
Closed by a test
Sealed assemblies are proof-tested, so the model is closed by a measurement rather than by a report. A model that is never contradicted is not a validated one.
Fed by data
Model updates come from test data, and the deviation figure is stated rather than implied — so a reader can see how much of the answer is measurement.
The derivation behind the tolerance and leak bands is in the two engineering notes: blind-mate tolerance and helium leak testing.
Loop worksheet · pitch check · balance target
Send the stack-up before the layout is frozen.
A marked-up drawing comes back with the pitch that fits, the loop length that clears the door and the balance point the loop is checked at. Reading it costs less than re-cutting a tray.
Request spec sheet One business day · English quote + a one-page spec sheetThe worksheet set travels with the spec sheet — no download wall.
