Comparing Eyewash Systems

Military, manufacturing, and service personnel rely on safety directors to maintain the highest standards of quality--regardless of industry or location.

IN the open, sandy desert of a foreign country or in the confines of a maintenance work area, Master Sergeant Chad Lingerfelt strives to operate a safe work environment. As a ground safety manager for the U.S. Air Force, Lingerfelt supervises personnel who dismantle, clean, and reassemble aircraft all over the world. To protect his team from eye injuries, Lingerfelt has purchased a number of different emergency eyewash stations throughout his career, and he prefers portable eyewash stations.

"We have hundreds of portable emergency eyewash stations at Air Force bases because they are compact and easily transportable," he said. "They use a buffered, filtered saline solution in sealed cartridges that have a shelf life of two years, and the station is available whenever and wherever we need it, without worry of contamination."

Lingerfelt noted that portable eyewash stations can be taken anywhere. The models he selected, with replaceable fluid cartridges, eliminate the need for access to clean water in emergencies. In many locations, especially foreign countries, it's nearly impossible to find a dedicated water source free of algae, bacteria, or iron build-up. "At one time, we used portable eyewash stations that required us to supply our own water, and we had to clean and refill the systems regularly," Lingerfelt said. "The fluid cartridges we use now eliminate that concern because we only have to visually inspect the eyewash stations."

Preparation and Compliance Preserve Sight
More than 1,000 eye injuries occur in the workplace every day, according to the U.S. Bureau of Labor Statistics, and injuries result when workers forget to wear their protective eyewear or the eyewear does not fit properly. While almost 70 percent of accidents result from sparks or flying and falling objects--many are smaller than the head of a pin--striking the eye, injuries don't always result from particles penetrating the eye of an unprotected worker. Even with safety eyewear, routine procedures that workers perform with toxic materials in the form of powder, mist, vapor, or liquid can cause damage or injury to the worker's eye.

"We use a lot of chemicals in the airplane hangar, and even the environmentally friendly solutions can injure eye tissue," Lingerfelt said. "Any eye injury," he added, "can result in lasting damage."

That's why the Occupational Safety and Health Administration, the American National Standards Institute (ANSI), and the National Society to Prevent Blindness recommend that emergency eyewash stations be readily available, in accessible locations, and they must be free of obstructions that inhibit immediate use of the equipment. ANSI mandates that all eyewash stations require no more than 10 seconds to reach, a standard that requires critical placement of the units. For example, at the Air Force base's airplane hangar, the nearest water source was far more than 10 seconds from the work area. That's why Lingerfelt chose portable stations with convenient, low-maintenance saline solution cartridges. "I'm a safety person," he said. "No matter what happens, an eyewash station is there, and workers are safe."

While ensuring an eyewash station is within a 10-second reach, safety directors must also examine the capacity and operation of the systems they choose. According to ANSI, all eyewash stations must be capable of producing a stream of flushing fluid not less than 0.4 gallons per minute (gpm) for at least 15 minutes. Lingerfelt found that some gravity-fed units decline in fluid pressure during the 15-minute timeframe, which reduces the flow rate and height of the flushing stream. He looked for a portable station that offers a constant flow rate throughout the entire 15-minute cycle for thorough flushing and full compliance with ANSI emergency eyewash standards.

In order for emergency treatment to be successful, eyewash station manufacturers recommend brightly colored eyewash stations so injured employees can quickly find emergency aid. Next, the actual design must provide an easy-to-use, comfortable setting and enough room to allow the eyewash fluid to irrigate and flush both eyes simultaneously. The injured worker requires hands-free operation because he or she will need to hold both eyes open in the stream of fluid. Therefore, the unit must remain on until it is intentionally turned off, and the on-off valve must be activated in one second or less.

Comfort While Flushing Injured Eyes
While plumbed and self-contained stations meet industry standards, each provides different levels of comfort. Although cold water was formerly acceptable, the American National Standards Institute's Z358.1-1998 standard mandates that both types of stations now use tepid water as the flushing fluid instead of a dedicated cold water source.

Additionally, the standard recommends that self-contained eyewash stations use a preserved, buffered saline solution rather than tap water because emerging medical evidence suggests municipal water is not ideal for flushing eyes because it can cause painful damage even to healthy eyes, according to leading physicians.

In a study conducted at the Louisiana State University Health Sciences Center and the Kentucky Lions Eye Center, and led by Dr. Roger Beuerman, professor of Ophthalmology at the Health Sciences Center, photos taken with a scanning electron microscope comparing the cells on the outer surface of a normal eye after flushing with tap water versus flushing with a buffered, preserved, pH-balanced saline solution found dramatic differences. After 15 minutes, tap water disrupted the healthy eye's protective epithelial layer and caused damage to the corneal cells. In contrast, flushing with the saline solution left the eye in a clinically normal condition.

"We found that flushing with tap water damaged three or more layers of the protective corneal epithelial," said Dr. Beuerman. "The cells flushed with a buffered, saline solution caused less damage to the epithelial cells of the eye, resulting in a quicker healing and recovery time."

As early as the 1960s and 1970s, the late Dr. Arthur H. Keeney, a noted ophthalmologist, industry pioneer, and former head of Wills Eye Hospital and dean of the University of Louisville School of Medicine, noted tap water was adequate in an emergency if nothing else was available, but when there's a choice, an isotonic, balanced saline solution is far preferable.

Water can cause pain in a healthy eye, so it's not surprising that industry records reveal injured employees rarely flush with water for the full 15 minutes. After the first few minutes, the pain becomes so extreme that they cannot continue to flush.

"The reason that the patient perceives pain is because tap water does not have the composition of human tears," said Dr. Henry Edelhauser, professor of Ophthalmology and director of Ophthalmic Research at the Emory University School of Medicine. "Tears are a naturally buffered, salt solution. Tap water is not buffered, nor does it contain any of the necessary salts."

In contrast to tap water, saline solutions contain an anti-microbial preservative proven to reduce the likelihood of causing additional damage to an injured eye. Most solutions combine select preservatives, including bactericide, fungicide, and algaecide additives, to inhibit bacterial growth. While these additives will inhibit bacterial growth, no preservative will prevent build-up over an extended period of time.

USAF's Lingerfelt chose a self-contained, gravity-fed station that dispenses a soft ribbon of purified, contaminant-free solution that is physiologically balanced to match human tears, offering users greater comfort than any other solution, according to experts.

"The pH of human tears is generally around 7.4," said Dr. Christopher Paterson, professor of Ophthalmology & Visual Science at the Kentucky Lions Eye Center, University of Louisville. "I believe saline solutions should be kept in the range of 7.1 to 7.7, with a target of 7.4."

Comparing Maintenance and Operation
The type of eyewash station, whether self-contained or plumbed, determines the flushing fluid and maintenance required.

Self-contained eyewash stations use a saline solution that is stored in sealed, replaceable fluid cartridges or is formed by mixing a concentrated formula with potable water. Factory-sealed fluid cartridges quickly and easily install in five minutes and have a 24-month shelf life if the unit is not activated. This two-year shelf life is determined by the date of manufacture and is more than four times longer than any other primary, self-contained eyewash station. These stations require a weekly visual inspection or an after-use cleaning. In contrast, stations using a mixed concentrate solution, which often expires after six months, are at risk for bacteria and must be cleaned and replaced in accordance with the manufacturer's instructions, regardless of use.

For regular maintenance, self-contained and plumbed eyewash stations that use tap water as the primary flushing fluid require more attention than portable, saline-solution stations. Personnel must physically remove the water weekly in self-contained systems and wash them out to remove mildew, iron build-up, or other contaminants. Plumbed eyewash units need to be activated weekly to verify proper operation and flush away any build-up that formed as a result of stagnant water, according to ANSI. If bacteria or mold are present in the station, it can result in flushing an injured eye with contaminated water.

Lingerfelt prefers easy maintenance at USAF bases and around the world. "We prefer the self-contained portable eyewash stations," he explained. "Cleaning the other stations added man-hours to maintenance costs in order to keep the units in compliance with OSHA and ANSI safety standards, but there's still no guarantee that all bacteria and residue were removed."

For disposal, self-contained stations have a valve or opening so flushing fluid can immediately flow into a separate waste disposal container or, if not available, onto the floor. Plumbed stations' flushing fluid drains as the water source would normally.

However, the portable stations Lingerfelt chose have a fluid reservoir that retains all waste flushing fluid, with a drain valve that allows for easy disposal after treatment--eliminating the need for additional equipment. "We don't have to worry about dumping the residue or cleaning the unit," he said.

Preventive safety measures and compliance remain in the forefront. Military, manufacturing, and service personnel rely on safety directors to maintain the highest standards of quality--regardless of industry or location.

For more compliance information, emergency eyewash and shower equipment should comply with regulations established by the ANSI Z358.1-1998 standard. This standard includes regulations for both plumbed and self-contained eyewash stations and establishes minimum performance and use requirements. It also discusses installation requirements, test procedures, maintenance, and employee training.

This article originally appeared in the October 2003 issue of Occupational Health & Safety.

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