Measurement Devices and Selection
Measurement Devices and Selection
This domain tests whether you can match a device to the test duration, building use, and QA requirements.
Core rules
- Passive devices include charcoal canisters (typically 2–7 days; sensitive to humidity and temperature), alpha-track detectors (1–12 months; integrate long-term exposure), electret ion chambers (short or long), and liquid scintillation charcoal.
- Active devices include continuous radon monitors (CRMs), which record hourly radon and often detect tampering, power loss, and movement. CRMs need current calibration and documented interference checks.
- Select by objective: short-term real estate tests often use CRMs or 48-hour charcoal; long-term tests use alpha-track or electret. Do not use a device outside its validated exposure window.
- Record device type, serial number, deployment and retrieval times, and lab calibration or expiration information.
Worked example
A 48-hour real estate test in an occupied house with a tight closing date calls for a calibrated CRM. It provides hourly data and tamper/motion records. A 90-day alpha-track answers a different question and would miss the transaction timeline.
Traps
Using an alpha-track for a 2-day test; deploying charcoal in a damp basement without checking humidity limits; skipping CRM calibration or anti-tamper checks; mixing device serials between locations; assuming all passive devices are interchangeable.