Kestrel 4600 Heat Stress Tracker with Compass Kestrel 4600 Heat Stress Tracker with Compass
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Kestrel 4600 Heat Stress Tracker with Compass

Product code: K4600 - 0846

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The Kestrel 4600 Heat Stress Meter with Compass provides two vital functions in one unit. Determine appropriate exposure to heat stress conditions for occupations with heavy gear requirements, such as HAZMAT response and fire-fighting and utilise wind speed and direction for plume prediction and modelling.

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The Kestrel 4600 Heat Stress Meter is an extremely reliable heat safety meter for emergency response personnel, fire crews, hazmat crews and others who need accurate, environmental readings in order to properly assess environmental conditions, create a heat stress management plan and maximise personnel safety of those in the field. The Kestrel 4600 provides real-time monitoring of indoor or outdoor conditions.

Manufactured from tough heat resistant materials designed to survive in extreme hot and cold temperatures, the Kestrel 4600 is an easy-to-use handheld weather meter that monitors heat-related environmental conditions quickly with the touch of a button. Easy to program and incredibly reliable in the field, the meter generates highly accurate Wet Bulb Globe Temperature (WBGT) readings within a single portable, lightweight device that doesn't require any water or a complicated set up to use.

The Kestrel 4600 is used to determine exposure to heat stress conditions within minutes of exposure to the environment. This handy, portable meter also lets users activate and set up to six customised heat stress warning zone thresholds to trigger onscreen notifications of dangerous conditions. A valuable tool that can save a life out in the field or indoors in extremely hot and smoky conditions, the Kestrel 4600 Heat Stress Meter sounds an alarm when the WBGT reaches a desired threshold or when it enters into an unsafe range, allowing field personnel to get to safer conditions or to notify them to take a water break in order to avoid dehydration or other heat-related illnesses.

For emergency personnel, hazmat crews and military personnel having to wear heavy gear combined with the constant threat of fire, chemical blasts or combustive materials can all contribute to the risk of heat-related injuries, including heat stress, heat stroke and even death. The Kestrel 4600 Heat Stress tracker enables constant monitoring of the environment reducing the risk, offering precise readings and several easy to use functions that provide data right at your fingertips. Lightweight and easy to use, the Kestrel 4600 Heat Stress Meter reduces the amount of equipment to be carried in the field whilst maximising the environmental data required including WBGT, the most common composite measurement used to determine exposure to heat stress conditions.

With the Kestrel 4600 Heat Stress instrument, fire-fighters, hazmat professionals, emergency services personnel, athletes and others who are at risk of heat-related injuries due to exposures to extreme indoor and outdoor conditions can easily monitor their environment with real-time WBGT readings. The lightweight, durable heat stress meter also includes a digital compass, allowing users to monitor wind direction for plume prediction. The Kestrel 4600 Heat Stress Meter also comes with a compact (2.5 x 2.5 x 6 in.) padded carry case, and a portable vane mount that can be mounted on any tripod for hands-free monitoring. Bluetooth enabled units can even transmit data to personnel inside a response vehicle.

Kestrel 4600 measures
• Wet Bulb Globe Temperature (WBGT)
• Naturally Aspirated Wet Bulb Temperature
• Globe Temperature
• Mean Radiant Temperature (MRT)
Kestrel 4600 also measures
• Current wind speed
• Average wind speed
• Maximum wind speed
• Wind direction
• Crosswind
• Headwind/tailwind
• Air, water & snow temperature
• Wind Chill
• Heat index
• Dew Point
• Relative Humidity
• Barometric pressure
• Altitude
• Density altitude
• Wet bulb temperature
• Digital compass
• Time & Date
Choice of measurement units
• kt, m/s, km/h, mph, ft/min, Beaufort
• °, cardinal points
• °C, °F
• %
• mbar, inHg, hPa, psi
• m, ft
• Speed ±3% of reading or ±0.1m/s
• Direction ±5°
• Crosswind, headwind, tailwind ±5%
• Temperature ±1°C
• Globe temperature ±1.4°C
• Relative humidity ±3%
• Dew point ±2°C
• Barometric pressure ±2.4mbar
• Altitude ±15m
Operational Range
• Speed 0.6 to 60 m/s
• Direction 360°
• Crosswind, headwind, tailwind 0.6 to 60 m/s
• Temperature -45 to +125°C
• Globe temperature -10 to +55°C
• Relative humidity 0 to 100%
• Barometric pressure 10 to 1100mbar
Specification Range
• Speed 0.6 to 40 m/s
• Direction 0 to 360°
• Crosswind, headwind, tailwind 3.8 to 40 m/s
• Temperature -29 to +70°C
• Globe temperature -29 to +60°C
• Relative humidity 5 to 95%
• Barometric pressure 750 to 1100mbar
Available options
• Bluetooth model
Kestrel 4600 features
• Small and easy to handle
• Waterless Wet Bulb Globe Temperature (WBGT) with user-settable warning
• 1" Black globe
• Exterior temperature, humidity and pressure sensors for fast, accurate readings
• Data capture up to 1889 readings
• Data charting
• Easy-to-read backlit display
• Minimum and Maximum values
• Digital compass
• Temperature-corrected humidity sensor
• User-replaceable impeller
• Patented impeller and sensor technology
• Customizable automatic and manual data logger
• Data upload (with optional PC interface or integrated Bluetooth wireless technology)
• Five languages (English, French, Spanish, German, and Italian)
• Flip-top impeller cover allows use of other functions while protecting the impeller
• Clock & Calendar
• Runs from 2 AAA batteries
• Available in yellow
• 5 year warranty
Typical applications
• Fire fighting
• HAZMAT response
• Military
Heat Stress
Human heat stress results from a combination of many environmental factors - air temperature and humidity along with radiant heat from the sun and surfaces, balanced by the cooling effect of breezes or air flow. The most common composite measurement used to determine appropriate exposure to heat stress conditions is Wet Bulb Globe Temperature or WBGT.
The Kestrel 4600 Heat Stress Tracker Provides Waterless WBGT Measurement

Until now, most accurate WBGT measurement tools were large, cumbersome to use (requiring the transport of distilled water along with the measurement unit) and/or expensive. NK have added a compact black globe thermometer to the already proven sensor suite of the Kestrel 4000 Pocket Weather Tracker, then built in advanced algorithms to calculate WBGT values within 2.2 deg C of the values obtained from a full-sized WBGT setup.

The Kestrel 4600 Heat Stress Tracker uses a 1" Black Globe which is calibrated to achieve the same measurements as a 6" globe.

The Kestrel 4600 Pocket Heat Stress Tracker fits in a pocket or small Kestrel Belt Carry Case and provides accurate waterless WBGT measurements within minutes of exposure to the air.

Primary Measurement Units Resolution Accuracy
(if less)
Wind Speed
or Air Velocity
m/s 0.1 Larger of 3% of reading, least significant digit or 20 ft/min 0.6 to 60.0 m/s
0.6 to 40.0 m/s
1 inch diameter impeller with precision axle and low-friction Zytel® bearings.
Start-up speed stated as lower limit, readings may be taken down to 0.4 m/s | 79 ft/min | 1.5 km/h | .9 mph | .8 kt after impeller start-up.
Off-axis accuracy -1% @ 5° off-axis; -2% @ 10°; -3% @ 15°.
Calibration drift < 1% after 100 hours use at 16 MPH | 7 m/s.
Replacement impeller (NK PN-0801) field installs without tools (US Patent 5,783,753).
ft/min 1 18 to 11,811 ft/min
118 to 7,874 ft/min
km/h 0.1 2.2 to 216.0 km/h
2.2 to 144.0 km/h
mph 0.1 1.3 to 134.2 mph
1.3 to 89.5 mph
knots 0.1 1.2 to 116.6 knots
1.2 to 77.8 knots
Beaufort 1 0 to 12 B
Temperature °F 0.1 1.8 °F 14.0 to 131.0
-20.0 to 158.0
Air, water or snow temperature. Hermetically-sealed, precision thermistor mounted externally and thermally isolated (US Patent 5,939,645) for rapid response. Airflow of 2.2 mph | 1 m/s or greater provides fastest response and reduction of insulation effect. Calibration drift negligible.
°C 0.1 1.0 °C -10.0 to 55.0
-29.0 to 70.0
Globe Temperature °F 0.1 2.5 °F -14.0 to 131.0
-20.0 to 140.0
Temperature inside 1inch|25mm black powder coated copper globe converted to Tg equivalent for standard 6inch|150mm globe. Closest equivalence obtained with airflow greater than 2.2mph|1m/s.
°C 0.1 1.4 °C -10.0 to 55.0
-29.0 to 60.0
Relative Humidity %RH 0.1 3.0 %RH 0.0 to 100.0%
5.0 to 95.0% non-condensing
Polymer capacitive humidity sensor mounted in thin-walled chamber external to case for rapid, accurate response (US Patent 6,257,074). To achieve stated accuracy, unit must be permitted to equilibrate to external temperature when exposed to large, rapid temperature changes and be kept out of direct sunlight. Calibration drift +/- 2% over 24 months. RH may be recalibrated at factory or in field using Kestrel Humidity Calibration Kit (NK PN-0802).
Pressure inHg 0.01 typical 0.04 inHg
max 0.07 inHg
0.30 to 32.48 inHg Air pressure at the location. Adjustable reference altitude allows display of station pressure or barometric pressure corrected to MSL. Monolithic silicon piezoresistive pressure sensor with second-order temperature correction. Pressure sensor may be recalibrated at factory or in field. Kestrel 2500 and 3500 display continuously updating three-hour barometric pressure trend indicator: rising rapidly, rising, steady, falling, falling rapidly. Kestrel 4000 series displays pressure trend through graphing function.
hPa (mb) 0.1 typical 1.5 hPa
max 2.5 hPa
300.0 to 1100.0 hPa 10.0 to 1100.0 hPa
PSI 0.01 typical 0.02 PSI
max 0.04 PSI
0.14 to 15.95 PSI
Wind Direction
Forward Heading
° 1 0 to 360° 2-axis solid-state magnetoresistive sensor mounted perpendicular to unit plane to permit operation while measuring wind speed. Declination/variation adjustable for True North readout. Accuracy of measurements dependent upon unit's vertical position. Self-calibration routine eliminates magnetic error from batteries or unit and must be run after every full power-down (battery removal or change).
Cardinal 16 Points 0 to 360°
Crosswind &
mph 1 7.1% Refer to stated ranges for wind speed. Effective wind relative to a target or travel direction. Calculated from wind speed, wind direction and target heading. Auto-switching headwind/tailwind indication.
ft/min 1 7.1%
km/h 0.1 7.1%
m/s 0.1 7.1%
knots 0.1 7.1%
Wind Chill °F 0.1 1.6 °F Refer to stated ranges for wind speed and temp. Perceived temperature resulting from combined effect of wind speed and temperature. Calculated based on the NWS Wind Chill Temperature (WCT) Index, revised 2001, with wind speed adjusted by a factor of 1.5 to yield equivalent results to wind speed measured at 10 m above ground. Specification temperature limits established by WCT Tables.
°C 0.1 0.9 °C
Heat Index °F 0.1 3.6 °F Refer to stated ranges for temp. and relative humidity. Perceived temperature resulting from the combined effect of temperature and relative humidity. Calculated based on NWS Heat Index (HI) tables. (Specification temperature limits established by HI tables.)
°C 0.1 2.0 °C
Outdoor Wet Bulb Globe Temperature (WBGT) °F 0.1 1.3 °F Refer to stated ranges for wind speed, temp., globe temp, relative humidity and pressure Measure of human heat stress defined as the combination of effects due to radiation, convection, and conduction. Outdoor WBGT is calculated from a weighted sum of natural wet bulb (Tnwb), globe temperature (Tg), and dry bulb temperature (Td). User settable on-screen warning zones.
°C 0.1 0.7 °C
Wet Bulb Temperature - Naturally Aspirated (Tnwb) °F 0.1 1.4 °F Refer to stated ranges for wind speed, temp., globe temp, relative humidity and pressure Similar to psychrometric wet-bulb temperature (see below). However, Tnwb only undergoes forced convection from the ambient air velocity. Tnwb is a measure of the evaporative cooling that the air will allow. This is accounted for by combining the effects of, mainly, relative humidity and wind speed.
°C 0.1 0.8 °C
Wet Bulb Temperature (Psychrometric) °F 0.1 3.2 °F Refer to stated ranges for temp., relative humidity and pressure. Temperature indicated by a sling psychrometer. Due to nature of the psychrometric ratio for a water-air system, this approximates the thermodynamic wet-bulb temperature. The thermodynamic wet-bulb temperature is the temperature a parcel of air would have if cooled adiabatically to saturation temperature via water evaporating into it.
°C 0.1 1.8 °C
Dewpoint °F 0.1 3.6 °F Refer to stated ranges for temp. and relative humidity. Temperature to which the air must be cooled at a constant pressure for water vapour to condense into water. Calculated from temperature and relative humidity.
°C 0.1 2.0 °C
Altitude ft 1 typical 50 ft
max 98 ft
-2,300 to 85,000 ft Height above Mean Sea Level ("MSL"). Temperature compensated pressure (barometric) altimeter requires accurate reference barometric pressure to produce maximum absolute accuracy.
m 1 typical 15 m
max 30 m
-700 to 25,900 m
Density Altitude ft 1 246 Refer to stated ranges for temp., relative humidity and pressure. Air density converted to equivalent sea level elevation at the International Standard Atmosphere. Calculated from temperature, pressure and relative humidity.
m 1 75
Max/Avg Wind Max and average wind calculation may be started and stopped independently of data logging of other values, along with all other wind-related functions: air velocity, crosswind, headwind/tailwind, wind chill, WBGT, TWL, evaporation rate.
Data Storage & Graphical Display, Min/Max/Avg History Minimum, maximum, average and logged history stored and displayed for every measured value. Large capacity data logger with graphical display. Manual and auto data storage. Min/Max/Avg history may be reset independently. Auto-store interval settable from 2 seconds to 12 hours, overwrite on or off. Logs even when display off except for 2 and 5 second intervals (code version 4.18 and later). Data set capacity = 1889.
Data Upload Requires optional PC interface (USB or RS-232) or Bluetooth enabled model and provided software.
Available Bluetooth®
Data Connect
Adjustable power consumption and radio range from up to 30 ft | 9 meters. Individual unit ID and 4-digit PIN code pre-programmed for easy identification and data security when pairing and transmitting. Employs Bluetooth Serial Port Protocol for data transmission.
Display & Backlight Multifunction, multi-digit monochrome dot-matrix display. Choice of aviation green or visible red (NV models only) electroluminescent backlight. Automatic or manual activation.
Response Time & Display Update All measurements except those based on relative humidity respond accurately within 1 second. Relative humidity and all measurements which include RH in their calculation may require as long as 1 minute to fully equilibrate to a large change in the measurement environment. Display updates every 1 second.
Clock / Calendar Real-time hours:minutes:seconds clock, calendar, automatic leap-year adjustment.
Operational & Storage Temperature Range The operational temperature range of the liquid crystal display and batteries is 14° F to 131° F / -10 °C to 55 °C. Measurements beyond the operational range can be taken by briefly exposing unit to extreme conditions such that the display and batteries remain within the operational range. Storage range -22 °F to 140 °F / -30 °C to 60 °C.
Auto Shutdown User-selectable -- 15 or 60 minutes with no key presses or disabled.
Languages English, French, German, Italian, Spanish.
Certifications CE certified, RoHS and WEEE compliant. Individually tested to NIST-traceable standards (written certificate of tests available at additional charge).
Battery AAA Alkaline, two, included. Average life, 400 hours of use, reduced by backlight or Bluetooth radio transmission use.
Environmental Waterproof (IP67 and NEMA-6). MIL-STD-810F, Transit Shock, Method 516.5 Procedure IV; unit only; impact may damage replaceable impeller.
Size & Weight 6.5 x 2.3 x 1.1 in / 16.5 x 5.9 x 2.8 cm, 4.4 oz / 125 g.
The manufacturer reserves the right to amend the specification and therefore the information in this document may be subject to change