Kestrel 5400 Heat Stress Tracker PRO (0854ORA)

Kestrel 5400 Heat Stress Tracker Pro (Orange) (0854ORA)

How Does the Kestrel 5400 Work?

The Kestrel 5400 uses a 1-inch black globe to gather information about the environment, which isn’t possible with current Kestrels. As is true with the original Wet Bulb Globe Temperature apparatus, a temperature sensor is installed inside the globe that will measure the temperature inside. The temperature inside the globe is a function of the ambient air temperature, solar insolation and wind speed.

As one can imagine, a sunny day will make the globe hotter because it’s painted black, and colder ambient temperatures will have a tendency to cool off the globe. Lastly, the wind will cause the globe to get closer to the ambient air temperature because it will carry heat away from the globe when the air is cooler, or increase heat transfer to the globe if the air is warmer than the globe.

The Kestrel must sit out for a period of time to allow the globe to adjust to true atmospheric conditions; we recommend a minimum of 7-10 minutes. The globe temperature is then taken into account along with other measurements, such as ambient temperature, humidity and pressure, to calculate more meaningful measurements, such as Wet Bulb Globe Temperature and Thermal Work Limit.

Indoor Use

Reading the WBGT is important even in indoor settings where heat stress is a concern.  The Kestrel has an ‘indoor’ setting on the WBGT setting which basically turns off the function of taking into account the direct solar radiation from the sun.  It’s important to place the Kestrel in a representative area of the conditions that the workers face.  Remember, wind plays a factor in WBGT, so a vane mount can be used indoors as well.  In the case of a ceiling fan, if the Kestrel doesn’t pick up the ceiling fan, then you are essentially getting the “worst case” WBGT readings which is not actually a bad thing.  If the airflow is pretty strong from the fan and you want to have that factored in, you could mount the Kestrel sideways (vs vertical) so the impeller picks up the wind more realistically.  You can use the Clamp to achieve this.

Here is some good information on OSHA and WBGT values:

https://www.osha.gov/dts/osta/otm/otm_iii/otm_iii_4.html

Why Use WBGT as a Heat Stress Indicator vs. just using the Heat Index?

Wet bulb globe temperature (WBGT) is based on an equation that uses a combination of environmental elements to calculate the reading. The calculation is a measure of the heat stress in direct sunlight, which takes into account: temperature, humidity, wind speed, sun angle and cloud cover (solar radiation).

Heat index takes into consideration temperature and humidity, and is calculated for shady areas.

There is a difference.

Monitoring the WBGT of the environment is quickly becoming the accepted and preferred method of measuring heat stress. Several sports organizations use WBGT to assess the potential risk of environmental stress on athletes. These organizations include the National Athletic Trainers Association (NATA), National Collegiate Athletic Association (NCAA) and the Women’s Tennis Association (WTA).

Thermal Work Limit (TWL) The unit will also display a measure of human heat stress known as “Thermal Work Limit” which, is measured in terms of the heat energy a person can dissipate from their surface area in Watts per square meter (w/m2). The measurement is based upon Globe Temperature, Relative Humidity, Ambient Temperature, Barometric Pressure, Wind Speed, and four parameters specific to an individual and their clothing. 4 Settings with preset constants are pre-installed in meter however for more specific applications:

Iclo: Intrinsic Clothing Insulation Factor

See: https://www.ashrae.org/resources–publications/bookstore/standard-55-and-user-s-manual

Reference values: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.258.8876&rep=rep1&type=pdf

VPF : Vapor Permeation Factor

See https://www.ashrae.org/resources–publications/bookstore/standard-55-and-user-s-manual

• For reference values range between 0.37 – 0.45
• 0.37 is a Long sleeve shirt/tweed suit jacket & long, loose trousers
• 0.45 is shorts and a t shirt

Pos: Position of the body

• 1 for standing
• 0 for lying down

Area: Area of a human male

• Values are approximately 1.7m^2 or 1.8m^2
• Meter assumes 1.7m^2

TWL Reference Table:

The Kestrel Meter 5400 Heat Stress Meter measures/features

• Wet Bulb Globe Temperature (“WBGT”)
• Thermal Work Limit (“TWL”)
• Waterless! Natural Wet Bulb Temperature accurately calculated from on-board digital sensors with no tedious setup or maintenance.
• Large, hi-res, hi-contrast, graphic display is perfectly readable in the brightest sunlight and is backlit for use in low-light conditions.
• Globe Temperature
• Naturally Aspirated Wet Bulb Temperature
• Wind Speed (Current, Average, & Maximum)
• Altitude
• Pressure trend
• Barometric pressure
• Relative humidity in %
• Heat stress index
• Dewpoint
• Wet bulb temperature
• Density altitude
• Wind chill
• Air, water, and snow temperature °F or °C
• Waterproof
• Time and date
• Easy- to-read backlit display
• Data Logger (automatic and manual)
• Customizable data storage – 2900 data points
• Humidity sensor can be calibrated in the field with our Relative Humidity Calibration Kit.
• Customize screens to display user-selected measurements
• Graph and recall trends
• User-replaceable impeller
• Data charting
• Upload to a computer (with optional interface)
• Meets MIL-STD-810F 516.5 Procedure IV Transit Shock test – 20 drops from 5 ft. IP-67 sealed to exclude dust and water at 3 ft. submersion
• Five languages (English, French, Spanish, German, and Italian)
• US Patent Nos. 5,783,753 and 5,939,645 and 6,257,074
• Made in the USA
• 5 Year Warranty