CALCULATORS / PUMPS, FANS AND VENTILATION

Filter pressure drop interpolation calculator

Linear pressure-rise interpolation from supplied measured clean/end points.

pumps-filter-loading.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

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

Scenario	pressurePa
	125
	120

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.

filter change threshold125.00 Pa✓ passes

BASELINE INPUTS

clean50 Paloaded200 Pafraction0.5

CALCULATED

pressure125 Pa

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Filter pressure-drop allowance
# Scope: Linear pressure-rise interpolation from supplied measured clean/end points.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

clean = 50 Pa
loaded = 200 Pa
fraction = 0.5

pressure := clean+(loaded-clean)*fraction [Pa]

check filter change threshold: pressure <= 150 Pa

scenario alternative: clean = 40 Pa

Calculated from your source · not saved

Baseline · Baseline

filter change threshold125.00 Pa ✓ passes

alternative · alternative

filter change threshold120.00 Pa ✓ 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.

pressure: pressure = clean+(loaded-clean)*fraction [Pa]

Original worked example

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

Given

clean: 50 Pa
loaded: 200 Pa
fraction: 0.5

Calculated

pressure: 125 Pa

Assumptions and limits

Linear pressure-rise interpolation from supplied measured clean/end points.

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: Filter pressure-drop allowance. Inputs: clean and loaded curves; flow; replacement criterion. Outputs: system pressure allowance; conditional replacement threshold. Model scope: Measured or manufacturer curves and declared fluid conditions. 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: clean and loaded curves, flow, replacement criterion
Outputs: system pressure allowance, conditional replacement threshold
Modes: calculate, compare, sweep
Drawing: System and equipment curves

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