Cleanroom & Contamination Control worked example

Particle Count Trend at 68% particle counter availability: a worked example

This worked example runs the particle count trend numbers for a tougher week than the baseline: 68% particle counter availability instead of the typical 94%. Estimate usable particle-count monitoring capacity from sample throughput, planned sampling cycles, instrument availability, and valid-sample yield.

The inputs for this scenario

  • Particle samples processed per monitoring cycle: 6 samples / cycle (held at the documented default)
  • Planned monitoring cycles in the period: 48 cycles (held at the documented default)
  • Particle counter availability: 68 % (the input this scenario stresses; the baseline uses 94)
  • Valid particle sample yield: 97 % (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Gross particle count trend = particle samples processed per cycle × planned monitoring cycles.
  • Usable particle count trend works out to 190 valid outputs at these inputs, and this is the headline figure for the scenario.
  • Gross particle count trend works out to 288 valid outputs at these inputs.
  • Particle Count Trend lost to room or instrument downtime works out to 92.16 valid outputs at these inputs.
  • Particle Count Trend lost to invalid samples, rejects, or holds works out to 5.88 valid outputs at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where particle counter availability sits at 94% and the headline result is 263 valid outputs, this scenario comes in 27.66% below the baseline at 190 valid outputs.
  • Use it when planning a monitoring period, justifying counter capacity to a quality lead, or diagnosing why your trend dataset has gaps. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Usable particle count trend: 190 valid outputs (headline result)
  • Gross particle count trend: 288 valid outputs
  • Particle Count Trend lost to room or instrument downtime: 92.16 valid outputs
  • Particle Count Trend lost to invalid samples, rejects, or holds: 5.88 valid outputs

Run it with your numbers

  • To rerun this with your own numbers, open the live Particle Count Trend calculator, set particle counter availability to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.