How to Measure Air Velocity in a Vent
Face the vane square to the flow, traverse the grille in a grid, average, multiply by free area. Ten minutes per vent.
Read Guide→Buying Guides
Research-based buying guides that compare the leading options by documented specifications, real use cases and value.
Best Gas Detectors for Home Inspectors: Sniffers and CO Meters for Inspection Reports
A two-range gas sniffer and a ppm carbon monoxide meter, the pair an inspector needs to document a gas appliance, plus a 4-gas monitor for crawl spaces.
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How to Choose an Environmental Meter
One handheld for airflow, temperature, humidity, light and sound. Worth it when you need all five occasionally.
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Best Hydrogen Gas Detectors: H2 Leak and Battery-Room Monitors Compared
Pumped H2 analyzers for leak tracing, a wall-mount battery-room monitor with relay outputs and a 0.1 ppm handheld, compared from manufacturer documentation.
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How to Choose a Light Meter
Cosine-corrected sensor, a stated spectral match, a range that covers your lighting, and LED capability if you measure LEDs.
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Best Ammonia Gas Detectors: NH3 Monitors for Refrigeration, Farms and Cleaning Chemicals
Portable NH3 meters compared from manufacturer documentation: 0 to 100 and 0 to 200 ppm ranges, temperature and humidity, alarm records and battery life.
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How to Choose a Sound Level Meter
Class 2 with a calibrator for anything that will be compared to a limit; unclassified for a rough idea; Class 1 for evidence.
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Best Oxygen Gas Detectors: O2 Monitors for Confined Spaces, Labs and Cryogenic Rooms
Single-gas oxygen monitors compared from manufacturer documentation: 19.5 percent low and 23.5 percent high set points, self test, certificates and battery.
Read Guide→How to Choose an Anemometer for HVAC Work
Vane for grilles, hot-wire for ducts and hoods, flow calculation built in, and a temperature reading you will use.
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Best Hydrogen Sulfide Detectors: Single-Gas H2S Monitors for Oilfield, Sewer and Plant Work
Clip-on H2S monitors compared from manufacturer documentation: the fleet-standard BW Clip, a half-second TopTes and a certified Forensics unit.
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How to Choose a Temperature and Humidity Data Logger
Accuracy, interval, memory, battery, export and an alarm. Match each to the job, from a fridge to a damp wall.
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Best Multi-Gas Detectors: 4-Gas Monitors for Confined Spaces and Plant Work
Four-gas O2, LEL, CO and H2S monitors compared from manufacturer documentation: two-year fleet clips, rechargeable display units and certified budget meters.
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