Cleanroom & Contamination Control worked example

Particle Count Trend at 99% particle counter availability: a worked example

What does the result look like when particle counter availability reaches 99%? The full calculation is worked below with real intermediate numbers. a team needs to confirm whether non-viable monitoring coverage can keep up with the sampling plan for a particle monitoring route

The inputs for this scenario

  • Particle samples processed per monitoring cycle: 6 samples / cycle (unchanged)
  • Planned monitoring cycles in the period: 48 cycles (unchanged)
  • Particle counter availability: 99 % (raised for this scenario; the documented default is 94)
  • Valid particle sample yield: 97 % (unchanged)

Working through the calculation

  • Applying the documented formula (Gross particle count trend = particle samples processed per cycle × planned monitoring cycles) to the inputs above produces each figure below.
  • At this operating point the engine returns 277 valid outputs for usable particle count trend, the number this scenario is built around.
  • At this operating point the engine returns 288 valid outputs for gross particle count trend.
  • At this operating point the engine returns 2.88 valid outputs for particle count trend lost to room or instrument downtime.
  • At this operating point the engine returns 8.55 valid outputs for particle count trend lost to invalid samples, rejects, or holds.

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 5.32% above the baseline at 277 valid outputs.
  • A figure at this level is achievable when particle counter availability is genuinely sustained, not just peaked for a shift. It assumes uptime and yield are independent steady-state rates; a single event like a HEPA breach, an isokinetic probe error, or a counter calibration drift can void far more samples than the averaged yield figure implies.

Results at a glance

  • Usable particle count trend: 277 valid outputs (headline result)
  • Gross particle count trend: 288 valid outputs
  • Particle Count Trend lost to room or instrument downtime: 2.88 valid outputs
  • Particle Count Trend lost to invalid samples, rejects, or holds: 8.55 valid outputs

Run it with your numbers

  • Every input above is editable in the live Particle Count Trend calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.