WORK PLANS - Laserfiche WebLink

Home Browse Search

NWB = Natural Wet Bulb Tem'peratu`re DB = Dry Bulb (air) Temperature GT = Globe Thermometer Temperature The determination of WBGT requires the use of a black globe thermometer, a natural (static) wet-bulb �f thermometer, and a dry-bulb thermometer. The measurement of environmental factors shall be performed as follows: 1. The range of the dry and the natural wet-bulb thermometers' should be -5°C to +50°C, with an accuracy of ±0.5°C. The dry bulb thermometer must be shielded; from the sun and the other radiant surfaces of the environment without restricting the airflow around the bulb.. The wick of the natural wet bulb thermometer should be kept wet with distilled water for at least one-half hour before the temperature reading is made. It is not enough to im6erse'the other end of the wick into a reservoir of distilled water and wait until the whole wick becomes wet by capillarity. The wick must be wetted by direct application of water from a syringej;one-half hour before each reading. The wick must cover the bulb of the thermometer and an equal length of additional wick must cover the stem above the bulb. The wick should always b'e clean, and new wicks should be washed before using. y 2. A globe thermometer, consisting of a 15 cm 6-inch in diameter hollow copper sphere( } pp p painted on the outside with a.matte black finish, or equivalent, must be used. The bulb or sensor of a thermometer(range -5°C to +100°C with an accuracy of±0.50C) must be fixed in the center of the .I sphere. The globe thermometer should be exposed at least 25 minutes before it is read. 3. A stand should be used to suspend the three thermometers sol;that they do not restrict free airflow € I around the bulbs and the wet-bulb and globe thermometer are root shaded. 4. It is permissible to use any other type of temperature sensor that gives a reading similar to that of a �' mercury thermometer under the same conditions. 5. The thermometers must be placed so that the readings are representative of the employee's work or rest areas, as appropriate. Once the WBGT has been estimated, employers can estimate workers'metabolic heat load and use the ACGIH method to determine the appropriate work/rest regimen, clothing, and equipment to use to control the heat exposures of workers in their facilities. !I' :T PERSONAL PROTECTIVE EQUIPMENT UREFLECTIVE CLOTHING l Reflective clothing, which can vary from aprons and jackets to suits that completely enclose the worker from neck to feet, can stop the skin from absorbing radiant heat. However, since most reflective clothing does not allow air exchange through the garment, the reduction of radiant heat must more than offset the corresponding loss in a.vaporative cooling. For this E reason, reflective clothing should be worn as loosely as pgssible'. In situations where radiant �1 heat is high, auxiliary-cooling systems can be used under the reflective clothing. AUXILIARY BODY COOLING + j 1. Commercially available ice vests, though heavy, may accommodate as many as 72' ice packets, which are usually filled with water. Carbon dioxide (dry ice) can also be used as a coolant. The cooling offered by ice packets lasts only 2 to''.4 hours at moderate to heavy heat STANTEC Consulting Corporation Attachment 8' t l