Content1. What is WBGT meter?
1.1 Working principle of WBGT meter
1.2 Structure of WBGT meter
1.3 Use of WBGT meter2. Heat stress meter
2.1 Heat hazard identification3. Heat stress WBGT meter
4. How to buy WBGT meter?
Several factors can contribute to the risk of occupational heat stress for workers. These factors include the following.
a. Environmental conditions
(e.g., temperature, humidity, sunlight, and wind speed), especially on consecutive days.
b. The presence of heat sources in the work area (e.g., hot tar stoves or fireplaces).
c. The level of physical activity
, i.e., the workload that results in body heat production.
d. Use of clothing or protective equipment that will reduce the body's ability to dissipate heat.
e. Personal/personal risk factors.
Heat-related illness prevention begins with determining the presence of heat hazards in the workplace. Two types of heat sources increase the risk of heat-related illnesses.
a) Ambient heat is generated by a warm or hot environment.
b) Metabolic heat generated by the body is related to workload (physical activity).WBGT meter
contains three different thermometers, a dry bulb thermometer for measuring ambient air temperature, a natural wet bulb thermometer for measuring evaporative cooling possibilities, and a black bulb thermometer for measuring radiant heat.WBGT monitors
should be placed near the working location. For example, if the work is in direct sunlight, then the WBGT instrument should be in sunlight. The WBGT has important advantages over other environmental thermal measurements. A major advantage is that the WBGT takes into account all four major ambient thermal factors - temperature, humidity, radiant heat, and wind. In contrast, standard thermometers assess only one factor (air temperature). The heat index is another commonly used measure of heat stress. It is measured in the shade and combines air temperature and relative humidity to represent heat under resting conditions. The heat index does not take into account the effects of sunlight, wind, radiant heat sources, or workload. Air (dry bulb) temperature also ignores relative humidity. All of these factors affect the total heat stress experienced by the worker.
Workplace ambient heat should be measured in the field using a WBGT meter
. The use of a heat index is a less desirable alternative. While local weather reports based on observatory weather data may be useful, the readings from these stations may not reflect the conditions at a particular work site. Thermal conditions at a job site can vary for a variety of reasons, from cloud cover and humidity to local heat sinks. The potential for error increases with the distance to the weather station.
In addition to possible distance-based errors, weather reports can be inaccurate if the job site has features that affect thermal conditions. These features include the following.
a. Indoor work. Weather forecasts do not measure conditions inside buildings.
b. Direct sunlight. The weather service measures temperatures and heat indices in the shade. Working in the sun may be hotter. Direct sunlight can increase the heat index by as much as 13.5°F (7.5°C).
c. Heat Source. Weather reports cannot account for the heat generated by fires, hot tar or other materials, heat-absorbing surfaces such as roads and roof surfaces, or heat-absorbing surfaces such as roads and roof surfaces.
d. Wind resistance. Some sites may be hotter than surrounding areas because structures impede airflow. Examples include trenches and bowl-shaped sports fields.
e. Reflective materials. Water, metal, or other materials that reflect sunlight at workers.
On sites with these characteristics, weather reports are unlikely to provide accurate estimates of ambient heat. Employers should use field measurements such as WBGT