PLR — Pressure Loss

CALCULATION

Water, chilled water, supply and exhaust air: Darcy-Weisbach runs and K fittings at one density.

START

Pipe · DN40 · G-N2_Distribution

Id 418302 · Level 01. A pump or fan outlet, the first pipe after it, or any run.

FLOW LEAVES THROUGH

Port 1 · DN40 · towards Regulator RG-01

Port 2 · DN40 · towards Ball Valve - Flanged

Untick the port the flow comes IN through, and any port that should not be followed.

FLOW

One total, shared among the outlets in proportion to their pipe area.

Use flows the model already has

Open ends count as outlets

FLUID

Temperature°C

Water: 998.2 kg/m³, 1.002 mPa·s.

PRESSURE

Needed at every outlet

Include height (static head)

METHOD

Elbows by their drawn bend radius

Open the report after export

Calculate reads the network from the start, then works out every flow and loss. Nothing is written to the model.

LOSS ON THE CRITICAL PATH

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PRESSURE AT THE WORST OUTLET

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TURN ON THE CRITICAL PATH

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TOTAL FLOW

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OUTLETS

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ELEMENTS READ

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NETWORKDistance from the start runs left to right; the critical path is drawn in the accent colour. Click an outlet to show it in Revit.

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Pressure loss from the pipework or ductwork alone

Pick the element the flow starts from, enter the pressure there and the flow, then Calculate. No equipment set-up is needed: every outlet and open end downstream takes its share of the flow.

Every place the flow ends, highest loss first. The first row is the critical path. Click a row to show the outlet in Revit; double-click to see its path.

Outlet

A section is a stretch with one flow and one size, in the shape of Revit's own report. Click a row to select its elements in Revit.

Critical path only

Fittings and accessories grouped by kind, size and coefficient, with where the coefficient came from. Click a row to select them in Revit.

What a fitting or accessory loses when the model holds no coefficient for it. A K the family carries, or one Revit worked out, is always used first.