WBGT, stands for Wet Bulb, Globe, Temperature. WBGT monitor measure the ambient temperature, the humidity and heat from any other heat source to yield an overall indicative heat stress number. However, WBGT can't measure several personal factors as age, gender, body type etc. So for a more personalized measure personal heat stress monitors are resorted to. These are the generalizations. For specific clarifications regarding heat stress monitors here is more help.

The alarm jack is connected to a relay. The normal condition of the relay (no for normally open or nc for normally closed) is set when the temperature alarm level is set. Then when the QT-15 goes into an alarm, the state of the relay will change.  External devices connected to the QT-15 alarm jack are turned on or off when that relay changes conditions.

Should I use the 6-inch or 2-inch globe?

The Globe part of the WBGT measurement calls for a 6-inch (15 cm) diameter hollow copper sphere painted matte black on the outside, or the equivalent. The standard QT-34 and QT-36 sensor bar comes with a 2-inch globe for faster response time. The temperature of the 2-inch globe is correlated to match that of a 6-inch globe.  An optional sensor bar with a 6-inch globe is available, if desired, but is not necessary.

Why would I need a QT-34/3 or QT-36/3 with three sensor bars?

When the temperature in the space surrounding a worker does not have a constant value, it is necessary to determine the WBGT index at three heights corresponding to the worker’s ankles, abdomen, and head. A weighted average is then calculated using those three WBGT measurements. This is based on ISO 7243:1989.  Also, one unit may be used to monitor three sensor bars at different locations of a plant, shop, or any area up to 100 feet away.

What is WBGT?

It stands for Wet Bulb Globe Temperature. It is a weighted averaged of the three sensors on an area heat stress monitor: the Wet Bulb, Globe, and Dry Bulb. The WBGT formula for indoor measurements is 0.7WB + 0.3G. The WBGT formula for outdoor measurements is 0.7WB + 0.2G + 0.1DB.

How is the QT-34 or QT-36 Area Heat Stress Monitor calibrated?

The End user can check the calibration of the area heat stress monitor using the calibration module that is shipped with the monitors. The calibration module is a small connector that plugs into the port on the top of the monitor where the sensor bar is usually assembled.  If the QT-34 or QT-36 is out of tolerance, then the monitor must be sent back to Quest for calibration.  There is no adjustment for the end user to make.

Why is the temperature sensor of the QT-II placed in the ear for personal monitoring?

There are several other ways of tracking core body temperature that work (down the esophagus, orally, anally, or via skin contact) but you need to find one you can work with. Most people would rather put an earplug in their ear than swallow a sensor, or one of the other methods. The sensor we use is mounted inside a standard foam earplug, so the sensor only goes as far as the earplug. The earplug has a Noise Reduction Rating of 22. The ear sensor tracks the temperature of the tympanic membrane, which is near the blood flow to the hypothalamus. The hypothalamus regulates body temperature.  At the time Quest was developing the QT-II personal monitor, the technology for taking temperatures using the ear sensor was becoming more acceptable in hospitals and is now available to consumers.

There are temperature levels on the QT-II Personal Heat Stress Monitor printout about 110 degrees Fahrenheit; how can this be?

A)The QT-II monitor should be calibrated to the individual in the environment where the wearer will be working.  If that environment changes by more that 10 degrees Celsius (18 degrees Fahrenheit), then the unit must be recalibrated.  If the QT-II is not recalibrated after that much of a temperature change, then the temperatures logged will appear very high.