Environment, Health and Safety

16.6 Heat and Heating Devices

16.6 Heat and Heating Devices

Heat hazards within laboratories can occur from a number of sources; however, there are some simple guidelines that can be followed to prevent heat related injuries. These guidelines include:

  • Heating devices should be set up on a sturdy fixture and away from any ignitable materials (such as flammable solvents, paper products and other combustibles). Do not leave open flames (from Bunsen burners) unattended. 
  • Heating devices should not be installed near drench showers or other water spraying apparatus due to electrical shock concerns and potential splattering of hot water. 
  • Heating devices should have a backup power cutoff or temperature controllers to prevent overheating. If a backup controller is used, an alarm should notify the user that the main controller has failed. 
  • Provisions should be included in processes to make sure reaction temperatures do not cause violent reactions and a means to cool the dangerous reactions should be available. 
  • Post signs to warn people of the heat hazard to prevent burns.

When using ovens, the follow additional guidelines should be followed:

  • Heat generated should be adequately removed from the area. 
  • If toxic, flammable, or otherwise hazardous chemicals are evolved from the oven, then only use ovens with a single pass through design where air is ventilated out of the lab and the exhausted air is not allowed to come into contact with electrical components or heating elements. 
  • Heating flammables should only be done with a heating mantle or steam bath.

When using heating baths, these additional guidelines should be followed:

  • Heating baths should be durable and set up with firm support. 
  • Since combustible liquids are often used in heat baths, the thermostat should be set so the temperature never rises above the flash point of the liquid. Check the SDS for the chemical to determine the flashpoint. Compare that flashpoint with the expected temperature of the reaction to gauge risk of starting a fire.

16.6.1 Heat Stress

16.6.1 Heat Stress

Another form of heat hazard occurs when working in a high heat area. Under certain conditions, your body might have trouble regulating its temperature. If your body cannot regulate its temperature, it overheats and suffers some degree of heat stress. This can occur very suddenly and, if left unrecognized and untreated, can lead to very serious health affects.

Heat stress disorders range from mild disorders such as fainting, cramps, or prickly heat to more dangerous disorders such as heat exhaustion or heat stroke. Symptoms of mild to moderate heat stress can include: sweating, clammy skin, fatigue, decreased strength, loss of coordination and muscle control, dizziness, nausea, and irritability. You should move the victim to a cool place and give plenty of fluids. Place cool compresses on forehead, neck, and under their armpits.

Heat stroke is a medical emergency. It can cause permanent damage to the brain and vital organs, or even death. Heat stroke can occur suddenly, with little warning. Symptoms of heat stroke may include: no sweating (in some cases victim may sweat profusely), high temperature (103? or more), red, hot, and dry skin, rapid and strong pulse, throbbing headache, dizziness, nausea, convulsions, delirious behavior, unconsciousness, or coma.

In the case of heat stroke, call 911 & get medical assistance ASAP! In the meantime, you should move the victim to a cool place, cool the person quickly by sponging with cool water and fanning, and offer a conscious person 1/2 glass of water every 15 minutes. There are a number of factors that affect your body’s temperature regulation:

  • Radiant heat sources such as the sun or a furnace. 
  • Increased humidity causes decreased sweat evaporation. 
  • Decreased air movement causes decreased sweat evaporation. 
  • As ambient temperature rises, your body temperature rises and its ability to regulate decreases.
  • You should be especially careful if:
    • You just started a job involving physical work in a hot environment. 
    • You are ill, overweight, physically unfit, or on medication that can cause dehydration. 
    • You have been drinking alcohol. 
    • You have had a previous heat stress disorder.

In order to prevent heat stress, please follow these recommendations:

  • Acclimatize your body to the heat. Gradually increase the time you spend in the heat. Most people acclimatize to warmer temperatures in 4-7 days. Acclimatization is lost when you have been away from the heat for one week or more. When you return, you must repeat the acclimatization process. 
  • Drink at least 4-8 ounces of fluid every 15-20 minutes to maintain proper balance during hot and/or humid environments. THIRST IS NOT A GOOD INDICATOR OF DEHYDRATION. Fluid intake must continue until well after thirst has been quenched. 
  • During prolonged heat exposure or heavy workload, a carbohydrate-electrolyte beverage is beneficial. 
  • Alternate work and rest cycles to prevent an overexposure to heat. Rest cycles should include relocation to a cooler environment. 
  • Perform the heaviest workloads in the cooler part of the day. 
  • There should be no alcohol consumption during periods of high heat exposure. 
  • Eat light, preferably cold meals. Fatty foods are harder to digest in hot weather.