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Fine-Tuning Emergency Shower Safety in the Workplace
Safety managers know all too well the serious risk of emergencies inherent in workplaces across a range of industries. Particularly vulnerable are work settings involving chemicals, gases, and other hazardous materials, which pose potentially dangerous threats to life, limbs, eyes, skin, and other body parts.
Considering eye injuries alone, 2,000 U.S. workers per day on average have a job-related eye injury that requires medical treatment, according to the Centers for Disease Control and Prevention. Eye injuries not only cause pain and suffering to employees, but also they add up to more than $300 million per year in lost production time, medical expenses, and worker compensation.
Consequently, every workplace is charged with having a solid emergency plan incorporating the correct types of safety shower equipment ready for immediate use. To optimize safety, it's essential to periodically review placement, installation, standards, and requirements, as well as the latest product advancements with emergency fixtures.
Emergency Response Job Site Assessment
During a walk-through, it's important to reference the ANSI/ISEA Z358.1-2009 emergency equipment standard, which outlines the specific requirements for emergency eyewash and drench shower equipment installation, testing, performance, maintenance, training, and use. MSDS sheets should be referenced to determine protection needs, as they highlight the first aid information indicating if drenching facilities are required. Some emergency equipment manufacturers also offer free job site evaluations and can help assess needs and potential problems.
In general, it's important to take into consideration factors such as product location, water supply, water temperature, accessibility, and equipment identification.
Types of Fixtures
Once potential hazards are identified, the facility's emergency eyewash and drench shower needs can be assessed. Equipment should be selected to address the level of exposure to workers and how many individuals will be affected.
Emergency eyewash stations
- effective for spills, splashes, dust, or debris likely to affect only the eyes
- provides a controlled flow of water to both eyes simultaneously
- delivers an uninterrupted, 15-minute supply of tepid water; plumbed units can supply a greater volume of water available to the user--between 7.5 and 19.0 liters (2.0 and 5.0 gallons) per minute
Emergency eye/face wash stations
- used when the entire face is at risk from spills, splashes, dust, and debris
- irrigates the eyes and face simultaneously
- provides a large distribution pattern of water (minimum 11.4 lpm/3.0 gpm) to effectively rinse the entire face
- used when larger areas of the body are at risk
- flushes a larger portion of the body but is not appropriate for the eyes (a combination eyewash and drench shower may be used to simultaneously flush the eyes and rinse larger areas of the body)
During a walk-through, a safety or heath advisor should be consulted in locating fixtures correctly to make sure all workers are protected. Again, it is essential to reference the Z358.1 emergency equipment standard.
Guidelines for product placement include:
- A drench shower, eyewash, or combination unit should be located within 10 seconds of any worker at risk for chemical exposure. The distance a worker can travel in this time frame is estimated to be 55 feet. Battery-handling areas should have fixtures within 25 feet.
- The equipment must be on the same level the user is working on. If there are doors between the hazard and the fixture, they must swing in the direction of travel.
- If the worker's ability to walk or move can be impacted by the chemical exposure, place the fixture closer to the worker.
- When highly corrosive chemicals are used, place the drench shower or eyewash immediately adjacent to the hazard.
- If a potential chemical spill in an area is likely to affect multiple workers, make sure a sufficient number of fixtures are installed so a worker needn't wait 15 minutes while another is drenched.
It's also important for safety fixtures to be clearly identifiable and easy to reach:
- Keep the area around the fixture well lit.
- Identify each fixture with a highly visible sign. Yellow is often the easiest to see.
- Install eyewash sprayheads a minimum of 6 inches from walls or obstructions to allow the user clear access for eye flushing.
- Make sure the area for flushing under drench showers is unobstructed. The only exception is the eyewash on a combination drench shower and eyewash fixture. In this case, the eyewash is placed in line with the drench shower to allow for simultaneous use.
Tepid Water Delivery Systems
Tankless water heaters and emergency thermostatic mixing valves are both effective solutions for delivering tepid water consistently and reliably to emergency fixtures. Both technologies help to ensure that the user will stay in the water rinse for the full ANSI-required 15 minutes. However, not all systems are the same. The following are some key product features to consider when selecting a system:
Electric tankless water heaters
Newer tankless water heating systems are highly efficient solutions for providing an unlimited supply of tepid water for use in eyewash and drench shower systems. These models draw energy only when needed, reach the ANSI standards for tepid water temperatures in 20 to 30 seconds, hold outlet temperature to within ± 1 degree F, and have a low pressure drop (as low as 8 pounds per square inch). These features minimize potential post-installation complications that could be caused by a sudden decrease in pressure.
Some newer water heaters are designed with redundant safety and anti-scald features to meet ANSI tepid water requirements. They also provide overshoot purge protection that will automatically open to purge excess hot water whenever necessary.
Because today's tankless water heaters draw energy only when needed, they can provide great operational efficiency and lower energy expenses. In addition to energy savings, installation is very easy because only one electrical connection and a cold water line are needed, saving labor time and additional expenses.
Rightsizing tankless water heaters is critical because there are many variables that affect the correct sizing, such as flow rate, temperature rise, and the available power supply. When calculating temperature rise, it's important to base this from the annual coldest groundwater temperature. Be sure to carefully review the product’s technical data to select the right-sized heater for the application.
With TMVs, the hot and cold water is brought into the valve where it is mixed together and then routed over an internal thermal element called a thermostat. The thermostat continuously maintains the temperature of the mixed water flowing through the TMV. If the tempering design involves the selection of a TMV, be sure to select a valve that is an emergency thermostatic mixing valve with a cold water bypass and not a standard valve
It is important to use TMVs designed specifically for supplying tepid water to emergency fixtures. As opposed to standard thermostatic mixing valves, those designed for use with emergency fixtures valves feature a cold water bypass. Should the thermostat fail or the valve lose its hot water source for any reason, the cold water would still be allowed to flow through the valve to the emergency fixture. If the cold supply is lost, the valve will shut off and prevent the hot water from flowing through the valve to the emergency fixture. This protects the user from the potential dangers of a hot flushing fluid being supplied to the eyewash or shower.
A New Generation of Emergency Fixtures
Recently, several significant improvements have been made to flow control, coverage, and efficacy of eye/face washes and drench showers. The newest eye/face wash fixtures deliver a more uniform and complete rinse pattern to reach the entire face. The improvement covers more of the face than earlier models and provides for a faster and more effective rinse over the affected area.
Older shower designs push the flow of water to the outer rim of the showerhead, creating a hollow space in the center of the pattern that can miss affected areas. Using fluid dynamics technology, the new shower designs work together with a pressure-regulated flow control and the spinning motion of water, creating a spray pattern to rinse off the injured areas as quickly and thoroughly as possible. The contoured shape coupled with the spinning water funnels the drench into a concentrated, yet soft, deluge to ensure the most effective flush available.
Due to stagnant water left from required weekly testing, tampering and other misuse by workers, eye/face washes can become contaminated with dirt and bacteria. Newer eyewash designs come equipped with either plastic or stainless steel dust covers that shield the entire bowl. In some products, the hinged dust cover is clear, allowing for quick and easy visual inspection. Opening the dustcover cover starts the flow of water immediately, giving the user immediate relief.
New-generation eyewashes incorporate a self-draining design that eliminates any stagnant water in the system. They also feature clearly separated supply and waste pipes with all supply connections above the bowl to prevent cross-contamination from the clean inlet and waste water.
Getting Expert Input
Consulting with a third-party safety consultant and/or an emergency equipment product manufacturer can help engineers, designers, and owners formulate and/or review a solid safety plan customized for different types of facilities. As new shower technologies advance and evolve, safety managers have better tools to augment their safety programs.
This article originally appeared in the July 2014 issue of Occupational Health & Safety.