CALCULATORS / PNEUMATICS, HYDRAULICS AND VACUUM

Vacuum pump-down time calculator

Constant pumping speed, isothermal fixed vessel, no leaks/outgassing.

pneumatics-vacuum-pump-down.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

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

Scenario	durations
	48.2831
	38.6265

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.

pump down budget48.28 s✓ passes

BASELINE INPUTS

volume10 LpumpingSpeed20 L/mininitialPressure100 kPafinalPressure20 kPa

CALCULATED

duration48.283 s

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Vacuum pump-down time
# Scope: Constant pumping speed, isothermal fixed vessel, no leaks/outgassing.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

volume = 10 L
pumpingSpeed = 20 L/min
initialPressure = 100 kPa
finalPressure = 20 kPa

duration := volume/pumpingSpeed*log(initialPressure/finalPressure) [s]

check pump down budget: duration <= 60.0 s

scenario alternative: volume = 8 L

Calculated from your source · not saved

Baseline · Baseline

pump down budget48.28 s ✓ passes

alternative · alternative

pump down budget38.63 s ✓ 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.

duration: duration = volume/pumpingSpeed*log(initialPressure/finalPressure) [s]

Original worked example

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

Given

volume: 10 L
pumping speed: 20 L/min
initial pressure: 100 kPa
final pressure: 20 kPa

Calculated

duration: 48.2831 s

Assumptions and limits

Constant pumping speed, isothermal fixed vessel, no leaks/outgassing.

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: Vacuum pump-down time. Inputs: chamber volume; pump-speed model; start/end pressure. Outputs: idealized pump-down time. Model scope: Pressure, flow and actuator geometry with compressibility assumptions. 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: chamber volume, pump-speed model, start/end pressure
Outputs: idealized pump-down time
Modes: calculate, compare, sweep
Drawing: Actuator and circuit diagram

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