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CALCULATORS / SEALS, O-RINGS AND LUBRICATION

Small-gap leakage screening calculator

Laminar rectangular narrow-slot leakage; Newtonian fluid, no roughness/contact effects.

seals-leakage.napkin / editable
✓ checks pass

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

ScenarioflowmL/min
1
0.512

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

leakage budget1.00 mL/min✓ passes

BASELINE INPUTS

CALCULATED

flow1 mL/min

Edits change the baseline source.

Calculated from your source · not saved
Baseline · Baseline
leakage budget1.00 mL/min ✓ passes
alternative · alternative
leakage budget0.51 mL/min ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

flow
flow = width*gap^3*pressure/(12*viscosity*length) [mL/min]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

gap
10 um
width
10 mm
length
5 mm
pressure
100 kPa
viscosity
0.001 Pa*s

Calculated

flow
1 mL/min

Assumptions and limits

Laminar rectangular narrow-slot leakage; Newtonian fluid, no roughness/contact effects.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Small-gap leakage screening. Inputs: gap geometry; fluid viscosity; pressure; flow regime. Outputs: conditional leak rate; gap sensitivity. Model scope: Nominal gland geometry with material and supplier criteria. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

  • Inputs: gap geometry, fluid viscosity, pressure, flow regime
  • Outputs: conditional leak rate, gap sensitivity
  • Modes: calculate, compare, sweep
  • Drawing: Seal cross section

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS

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