Effects of wick contamination and thermal component variation on thermal indices

Date

1986-05

Journal Title

Journal ISSN

Volume Title

Publisher

Texas Tech University

Abstract

An experiment was performed in order to provide solutions to several problem areas in the assessment of the hot working environment. The following areas were studied:

  1. Effect of wick contamination on wet bulb thermometer and Botsball.
  2. Effect of wick wetness on Botsball temperature.
  3. Effect of thermometer shielding against radiant heat on natural wet bulb temperature.
  4. Effect of air velocity and radiant heat on the relationship between natural wet bulb temperature and psychrometric wet bulb temperature.
  5. Effect of air velocity on globe thermometer response.
  6. Intercomparison of thermal indices (WBGT, WGT, ET*, HSI, DTLV, ISODLE) under varying thermal components.
  7. Wet Bulb Globe Temperature and Wet Globe Temperature relationship under varying thermal components.
  8. Development of a simple to determine and use exposure limit to the hot environment. Several environmental measurements were made throughout the experiment.

Also, several thermal indices were calculated using the environmental data obtained. Several findings of the study are as follows:

  1. Wick contamination causes significant errors in the measurement of natural wet bulb temperatures. A set of general rules to correct errors is provided.
  2. Wick contamination does not cause errors in the measurement of Botsball temperatures.
  3. The wetness of the Botsball wick does not affect the measurement of Botsball temperatures.
  4. Radiant heat and air velocity affect the measurement of natural wet bulb temperatures. The relationship between shielded and unshielded natural wet bulb temperatures is found as a function of air velocity and radiant heat. Also, the relationship between natural wet bulb temperature and psychrometric wet bulb temperature is found under various radiant heats and air velocities.
  5. Globe temperature is reduced due to increased air velocity, although other thermal components are kept constant. The relationship between globe temperature and air velocity is found.
  6. WBGT, WGT and ET* operate in the same manner under varying environmental conditions. The relationship between WBGT and WGT under varying thermal components is developed.
  7. HSI does not predict heat stress properly under hot and humid conditions.
  8. Accurate prediction of exposure limit to the hot environment can be made by the use of the Predicted Duration Limit Exposure (PDLE) which is developed during this study.

Description

Keywords

Wet-bulb thermometers, Heat -- Physiological effect, Temperature measurements, Industrial hygiene, Air -- Pollution

Citation