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Scalding Tap Water and Serious Burns
Preventing serious tap water scalds is relatively easy. You must realize the hazards of too hot tap water. You then need a basic knowledge of your water heater’s thermostat function. Finally, you must conduct a simple test to ensure 120°F water.
Statistics in this report were gathered using the National Fire Incident Reporting System (NIRS), which is comprised of local fire departments as well as state and federal fire authorities.
For 2008, an estimated 216,000 individuals visited hospital emergency rooms because of various burn injuries.
These injuries were categorized as follows: 42 percent thermo burns from non-fire causes such as contact with a hot radiator, 28 percent (60,000) scalds, 13 percent thermal burns from fire causes and 17 percent miscellaneous.
Although not specifically stated, we may expect many of the 60,000 scalds reported resulted from too hot tap water.
Children under the age of 15 were the most susceptible to scald burns. They comprised 36 percent of the total scalds reported, which is over 21,000 burns.
Anatomy of the Skin and Burns
Human skin is comprised of two distinct layers, the epidermis and the dermis. The epidermis is the most outer layer of skin that contains skin cells but has no blood vessels or nerve endings. Its thickness is about 0.8 mm.
The next skin layer is the dermis; it contains blood vessels, nerve endings and has thickness of about 2 mm. A first-degree burn causes minor harm to the epidermis but no permanent damage. Most discomfort from a firstdegree burn results from exposure of the superficial blood vessels, which causes reddening of the skin.
A second-degree burn involves damage to both the epidermis and the dermis, generally resulting in blistering the epidermis.
A third-degree burn involves more damage to the dermis than a seconddegree burn resulting in open sores. These burns cause permanent skin damage, the formation of scar tissue and require skin grafts.
For the purpose of our discussion, serious burns will be defined as fullthickness, that being the complete destruction of the epidermal. Serious burns include all third-degree burns and many second-degree burns.
Most adults know contacting very hot water can result in a burn. However, most adults don’t know contact with, for example, 150 F water will cause a serious skin burn in two seconds, or that serious burns will occur with a six second exposure with 140 F water, or a 30 second exposure with 130 F water.
Two major studies involving in part, tap water scalds, were released in 1975 by the U.S. Consumer Products Safety Commission (CPSC).
The first study was written by Calspan, a CPSC contractor, which was issued under “The Investigation of Safety Standards of Flame Fire Furnaces, Hot Water Heaters, Clothes Dryers and Ranges.”
The other study was performed by another CPSC contractor, ABT Associates, and its report titled: “A Systematic Program to Reduce the Incidents and Severity of Bathtub and Shower Area Injuries.”
Both of these studies cite the timetemperature burn relationship of hot tap water, as reported by researchers Moritz and Henriques in 1947.
NEISS (National Electronic Information Surveillance System) data was used to obtain injury statistical sampling of hospital emergency rooms. The studies indicated the need for scald devices and to set water heater thermostats at 120 F.
During the early to mid 1980s, water heater manufacturers began placing warnings on their products. Printing on thermostat knobs stated: “Caution Hotter Water Increases the Risk of Scald Injury.” Also, printed warnings were attached to water heaters citing water over 130 F may cause scalding.
In 1991, the water heater manufacturers consensus standard (ANSI) American National Standard Institute Z21.10.1a-1991 included a pictorial scald warning depicting a possible burned hand under a bathtub’s hot water spigot. The warning states: “Danger, Water Temperature Over 125 F Can Cause Severe Burns Instantly or Death From Scalds.”
There are three major U.S. plumbing codes, Uniform Plumbing Code (UPC), Standard Plumbing Code (SPC), and the International Plumbing Code (IPC).
There is general agreement in the plumbing industry that tap water temperatures above 120 F are not safe and proper precautions are required to reduce this scalding hazard.
For residential applications, the most widely used device for preventing tap water scalds is the pressure balancing control valve. These devices were required by plumbing codes starting during the early to mid 1990s.
These would be installed as either the control valve for the combination tub and shower unit, or for just the shower stall. Most of these valves are designed with a flexible diaphragm in combination with a cylinder bored with two holes, one for hot water and one for cold water. The edges of the diaphragm serve as valve seats, which control the both the hot and cold water entering and exiting the valve.
With a pressure balancing valve, a drop in pressure of cold water would move the cylinder inside the diaphragm toward the cold side, allowing more cold water to enter the control valve and less hot water.
The key to proper operation of a pressure balancing control valve is its initial setting.
In the past these devices were required only for stand-alone showers and combination shower and bathtubs, not bathtubs without showers such as those equipped with whirlpool jets. However, current plumbing codes now require similar scald protection devices for these types of installations.
Since 1996, our firm has been involved with over three-dozen scald cases involving excessively hot tap water. Some cases centered on landlord liability, which pertained to the necessity of maintaining a safe property for tenants.
Other cases focused on contractor liability, such as improper installation of the water heater. Product liability issues were also involved, usually against the water heater manufacturers, primarily for inadequate warnings.
Under the ANSI standard, the manufacturer is required to use a detent or legible mark on the heater’s adjustable thermostat, consistent with a water temperature of approximately 120 F. Each thermostat manufacturer uses a different type of adjustable dial for temperature settings.
First, if the home’s water heater is gas fired, check the setting of the thermostat on your water heater.
The heater’s thermostat control knob is usually visible on the outside of the heater. As noted above, this may require the need to refer to the water heater’s instruction manual.
If the setting is incorrect, reset the control knob according to the manual’s instructions for 120 F water.
If you reset the thermostat, wait a day before you test the water temperature. To test, start with the tap closest to the water heater. Run the water for at least several minutes over a candy or meat thermometer and then read the temperature.
If the tap water check indicates the water is too hot, simply turn the control knob to a lower setting.
Wait a day and then recheck the same tap water to ensure a 120 F temperature.
If the water is still too hot, repeat the above procedure to attain the correct temperature.
The thermostat on an electric water heater is located under a metal cover, which needs to be removed with a screwdriver. You will definitely need to read your heater’s instruction manual before attempting to reset the thermostat.
Remember, first turn off the main electrical connection to the water heater, either by switching a circuit breaker or by pulling a fuse. If the procedure appears difficult or confusing, we recommend you contact a service technician.
Preventing serious tap water scalds is relatively easy. First, you must realize the hazards of too hot tap water. You then need a basic knowledge of your water heater’s thermostat function. Finally, you must conduct a simple test to ensure 120 F water.
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Russell Fote & Associates, Inc. provides expert witness, forensic consulting and testimony services for plaintiff attorneys, defense attorneys and insurance company claims departments. Expert Safety Engineer. At Russell Fote & Associates, our purpose is to provide our clients with the very best safety engineering and expert consulting services.
Since starting Russell Fote & Associates, Mr. Fote has given over 150 depositions and has testified at 25 trials. He has been recognized as an expert in the state courts of: Illinois, Wisconsin, Iowa, Kentucky, Tennessee, Nebraska, Oklahoma, and West Virginia, plus U.S. District Courts in Atlanta, GA and Central Islip, NY.
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