I am one of the safety guys. I was not at work. I was at home. A few months back I purchased a couple of gallons of muriatic acid to clean up some floor tile after a poor grouting job. I used up one jug and set the other at the side of the house away from pets and people. I forgot about it until I spotted it while I was doing yard work last weekend. I was hot and sweaty, in shorts and without any gloves but decided to move the container anyway. When I picked it up, the sun-brittled plastic crumbled and the gallon of acid covered my right hand and forearm and my right shoe. Luckily, a garden hose with a drench nozzle was just across the driveway because I was preparing to wash the car. My hand and arm began to heat up quickly as I ran to turn the hose on myself. No one else was home, and I alternated drenching my hand and arm while trying to remove my shoe and sock. Fortunately, this was only a weak acid and my foot was not affected. I continued to flush my hand and arm until there was no hint of burning or heat, and there was no serious injury. But this got me thinking.
I remembered the tragic UCLA accident just a few short years ago that resulted in a fatality from chemical burns.1 And then we had a string of chemical burn accidents at our university this spring, including boiling paraformaldehyde and sodium hydroxide solution, spilling a vial of 15 molar nitric acid, and pouring waste TRIzol®. So, maybe now is a good time to refresh all you laboratory folks on the use of safety showers and eyewash stations.
We are all familiar with OSHA and have heard the general requirement many times, but it doesn’t hurt to read it again. In 29 CFR 1910.151 Medical Services and First Aid, it states that “where the eyes or body of any person may be exposed to injurious corrosive materials, suitable facilities for quick drenching or flushing of the eyes and body shall be provided within the work area for immediate emergency use.”2 OSHA doesn’t give any more specifics regarding what immediate means or what constitutes suitable. How do we know if we are meeting the intent of the law? Fortunately, we have the American National Standards Institute (ANSI) and its consensus standard Z358.1, last updated in 2009. This ANSI standard is very detailed in defining what is appropriate for safety showers and eyewash stations. In fact, OSHA uses this reference as a guide when inspecting facilities.3 So let’s review what is “recommended” for acceptable safety equipment.
Check your installations – OSHA will
We begin with the hardware recommended by Z358.1. For safety showers, the showerhead must be capable of flowing 20 gallons per minute at 30 psi and able to produce a 20-inch diameter spray pattern at 60 inches above the surface where the user stands. The center of the spray head pattern should be at least 16 inches from any wall, door, or obstruction. It is recommended that the showerhead be mounted between 82 and 96 inches off the floor, with the valve no higher than 69 inches.
Eyewash stations target just the eyes and therefore have a lower flow requirement. ANSI Z358.1 recommends a flow of 0.4 gallons per minute also at 30 psi. The nozzles should be at least six inches from any obstruction and mounted between 33 and 45 inches above the floor. An eyewash gauge should be used to verify and test the flow pattern.
Requirements for all hardware
Both safety showers and eyewash stations must be capable of providing the recommended flow for at least 15 minutes. This usually translates into having the equipment plumbed in with hard connections to the water supply. Self-contained or personal wash devices are allowed but considered supplemental units that can provide immediate flushing while transiting to the permanent fixture.
If the local climate presents potential for freezing conditions, the equipment must be designed to avoid freezing or protected against that. Activation valves must open within one second and remain open until intentionally closed or turned off. It goes without saying that these safety devices should be constructed of corrosion-resistant materials.
The 2009 update to Z358.1 added two important criteria. The first is that the requirement for tepid water is now defined as having a temperature between 60 and 100 degrees Fahrenheit (15 to 37 degrees Celsius). The second change addresses simultaneous operation for combination units. This means that if you have a drench shower combined with an eyewash station, both devices must provide adequate flows and be fully operable at the same time.
Finally, and most important, let us look at the location of the equipment. I know you have the ten-second rule etched into your brain, or you should have, as that is the most critical element when it comes to safety showers and eyewashes. For all hazardous areas that need this equipment, travel time to the unit should be under ten seconds, which is about 55 feet. In addition, the drench shower or eyewash must be on the same level as the hazard, and there must be a clear path for travel. We recommend painting or marking the floor area underneath the shower to help keep it clear. Z358.1 also recommends that equipment be installed in a brightly lit area and marked with a highly visible safety sign.
Don’t forget about maintenance and training
Maintenance and training are often overlooked. But the last thing you want is to rush to the eyewash or shower only to be drenched with nasty, sediment-laden water. ANSI recommends flushing all equipment weekly to verify proper flow and clear the plumbing of any deposits. Remember to bring a large plastic trash can to catch the water, as these units are usually installed without any drains. The weekly flushing can also provide a great training opportunity to refresh the operation and travel paths for your employees.
If you are new to the laboratory, this article should get you thinking. If you are an experienced lab manager, then hopefully there is some useful information here to help you review your current equipment. We look forward to lots of reader feedback. Until next time, Stay Safe!
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