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Last month's article discussed the basics of emergency shower and eye/face wash equipment and how they are designed to meet corresponding standards and regulations. This month continues the discussion, while focusing on flushing and testing, and important considerations.
Flushing of emergency fixtures
It is recommended in the appendix of the standard to perform weekly flushing and performance tests to verify proper operation and temperatures of plumbed emergency equipment and to flush lines of bacteria, rust and stagnant water. These weekly tests should be recorded on a waterproof testing and flushing tag located on each emergency fixture. Emergency fixture water is often in a dedicated piping system, and can sit in the piping for long periods of time. If the piping system or the emergency fixture piping is galvanized it can become stagnant and rusty after a relatively short period of time. Most manufacturers offer stainless emergency fixture models that include stainless steel piping or interior epoxy coated metal piping. Plastic and copper have not been popular, because the material does not have the structural strength to allow for a self-supported sustainable fixture. Non-ferrous materials or coatings can help reduce the rust and iron oxide common in galvanized models. Copper supply or distribution piping can eliminate or significantly reduce the amount of rust and bacteria that is common in galvanized pipes. Weekly testing and flushing helps to clear the stagnant water, which includes bacteria and rust that can develop in the emergency fixture piping. Flushing also introduces fresh water with water treatment chemicals that can control bacteria growth until the chemical dissipates due to reaction with contaminants in the water and the pipe materials. Weekly testing and flushing will flush the piping system and introduce water treatment chemicals that will make sure stagnant water does not greet someone who may need to suddenly use the fixture in an emergency.
Testing of emergency fixtures
The appendix in the Z-358.1 Standard recommends annual flow and temperature tests for the full 15-minute duration. This test assures the tepid water supply temperature is properly sized and the temperature is adequate for the full 15-minute duration to encourage proper use of the emergency equipment.
Americans with Disabilities Act (ADA)
ANSI Z358.1 does not specifically address ADA, and ADA does not specifically address emergency fixtures. However, the ICC/ANSI A117.1 (2009): Accessible and Usable Buildings and Facilities is the standard referenced in the federal law under the ADA, and an employer should provide emergency fixtures that are suitable for handicapped employees that work in an area subject to a chemical hazard. Barrier-free emergency fixtures should include the following ANSI A117.1 requirements:
Designers should review provisions of ANSI A117.1 (2009): Accessible and Usable Buildings and Facilities and local accessibility regulations. There are several manufacturers that make units with under fixture clearance and emergency shower pull rods designed to meet ADA and ICC/ANSI A117.1 height and opening force requirements.
Emergency fixture locations
Determining emergency fixture locations is typically based upon the hazard. The following things should be considered when locating emergency fixtures:
Emergency fixture flow rates
Emergency fixture flow rates need to comply with the flow requirements in the ANSI/ISEA Z358.1-2014 - American National Standard for Emergency Eyewash and Shower Equipment. ANSI Z-358.1 Standard – Simultaneous Operation has the following language:
“The unit shall be…capable of supplying adequate flushing fluid to meet the requirements…when all components are operated simultaneously… and shall be positioned so that components may be used simultaneously by the same user.”
System design considerations:
Stand-alone tempering systems
There are remote areas in some buildings where instantaneous heaters can provide enough water for emergency fixtures to operate. The drawback to instantaneous water heaters is that they require a significant electrical service, or other utility service, out to a remote location. This can far exceed the cost of the emergency equipment needed to provide adequate heating of the flushing fluid at a flow that can range from a minimum of about 3 gpm or less for only an eyewash flowing to about 25 gpm for a combination shower and eye/face wash unit flowing while trying to maintain about a 50-degree rise in temperature.
The significant variation in flow calls for very sophisticated controls in order to not create a scalding issue. Some manufacturers of emergency equipment have come up with a stand-alone storage tank and mixing valve system that only needs an adequate cold-water supply and a 120-V electric circuit. The unit stores hot water in a storage tank with a small, low-wattage heating element that maintains the tank temperature that allows for mixing long enough to satisfy the flushing period, and that controls bacteria growth. A temperature actuated mixing valve designed to mix the hot water with cold water has provision to prevent temperature spikes upon initial operation. It delivers tepid water for the full 15-minute flow duration. This unit is ideal for schools and factories that need remote emergency equipment and have tight budgets.
Emergency drench showers, and combination shower eye/face wash units
Emergency showers or combination units flush a larger portion of the body (minimum 20 gpm for conventional shower applications, plus about 3 to 5 gpm for an eye/facewash.
Equipment location and installation requirements
Where chemical and biological materials are handled, emergency fixtures shall be located so as not to exceed 10 seconds (about 55 ft.) +/- from any point in a laboratory. ANSI Z358.1 requires the installation of emergency fixtures within 10 seconds of the hazard with an unobstructed path. Emergency showers and eye/facewash units should be located so as they can be used simultaneously. Offset units that provide a shower in one location and an eyewash over a sink or counter will not comply with the requirement for simultaneous use.
Emergency eyewash and shower fixtures shall be provided in areas where cleaning chemicals are handled and dispensed, medical/pathological waste areas, pH treatment rooms, hazardous material areas, chemical storage areas, and other areas where hazardous chemicals are used or otherwise deemed necessary through consultation with the safety, or medical personnel, or consultation with a chemist and chemical data sheets, or by the authority having jurisdiction.
Having at least one emergency shower and eyewash available for each laboratory space/area where hazardous materials are handled (such as a chemical fume hood, chemical storage, and other similar activities) is required. Where laboratories require MEP validation, emergency showers should be included in the process.
Emergency fixture installation considerations
1) Water supply
The ANSI Z358.1 standard states that the water temperature should be “tepid.” Appendix B of this standard (provided for information only) suggests a safe temperature range of 60 F to 100 F (16 C to 38 C). It should be noted, 80 F is in the middle of that temperature range and would probably be a good temperature to set the tempering valve that complies with ASSE 1071, however, some installations may require higher or lower temperatures, so each location should have the temperature set according to an analysis by qualified personnel of the hazard present. My own testing indicates the water temperatures below 70 F will be very uncomfortable and could lead to hypothermia or cold-water shock, which would not encourage the user to stay in the flow of water for the full 15-minute flush duration recommended by the ISEA/ANSI Z358.1 standard. The delivery of tepid water can create some plumbing design challenges.
2) Microbial growth
Systems that have been installed with large tepid water loops in buildings without water treatment systems on the circulated loop have experienced Legionella bacteria growth due to inadequate flushing or inadequate monitoring and treatment of the flushing water supply.
It should be noted that the new ASHRAE standard and the soon to be published ASHRAE Guideline 12, which will be titled Legionellosis: Risk Management for Building Water Systems, addresses how to control microbial growth in building water systems. The Z358.1 standard calls for weekly flushing in the appendix to bring in fresh chlorinated water to the fixture and annual compliance testing for the full 15-minute duration.
My experience is that some facilities flush very weakly (pun intended). Other installations that I have inspected were only flushing enough water to fill a 5-gallon bucket and they did not flush enough water to adequately purge the emergency fixture loop and branches of the stagnant water trapped within the system. This often happens when emergency fixtures are not provided with drains at the emergency fixtures.
I have spoken to manufacturers and building owners about the flushing frequency issue. Owners of large facilities with many emergency fixtures say they would like to change the standard to require monthly flushing or quarterly flushing to reduce labor costs. Larger facility owners say the current flushing requirements cause them to have a full-time team that rotates through the buildings and flushes the emergency fixtures into carts on wheels. Changing the standard to allow longer intervals between flushing will assure that many more installations will have bacteria-laden water for the first several minutes of flushing.
Some of the building owners’ representatives that I have consulted with have said with flushing, disposal, transporting, setting up of flushing equipment at a new location, and filling out the documentation and tags on the equipment, they typically flush about one fixture per hour. \
Manufacturers that I have talked to at several recent trade shows are now working on automatic flushing valves to flush the emergency fixture piping all the way up to near the flushing fixture outlets on an automatic and timed basis.
The flushing process should be calculated and adjusted to flow long enough to purge all the stagnant water in the emergency fixture piping system. In many cases this could mean up to twice the volume of the emergency fixture system to get ample flushing and bring water treatment chemical levels up to a level that controls bacteria growth.
When an emergency fixture system has a large volume and a circulated system with mixing valves and dead legs, consideration should be given to adding a water treatment system to the circulated portion of the piping system to monitor and add water treatment chemicals such as chlorine, chlorine dioxide, or mono-chlorines as needed to control bacteria growth. The piping should be designed to minimize dead-end piping. All dead-end piping should be piped to emergency fixtures or solenoid valves that are flushed on a timed schedule that will minimize bacteria growth.
It is not possible to prevent the ideal temperature for Legionella bacteria growth in emergency water systems, because the tepid water temperatures called for in the standard for flushing fluid temperatures in the ideal Legionella bacteria growth temperature range. Legionella bacteria will grow and multiply in temperatures between 68 F and up to about 122 F. The water source for the emergency fixtures should be potable and protected with an approved backflow preventer.
When the emergency equipment is plumbed with potable water, ANSI requires weekly activation of emergency fixtures for several reasons:
High hazard locations for combination units
Where large volumes of chemicals and concentrated corrosives are used, emergency showers serving chemical storage rooms, pH effluent treatment areas, and other areas deemed of high hazard, high-flushing 30 gpm emergency showers should be considered. Obstructions like doors, stacked materials and barrels and the path of travel to the emergency station should be clear of obstructions and straight as possible. Locating an emergency fixture outside the area of the hazard shall consider doors, door swing direction, and door hardware type as they can be considered an obstruction.
Next month's column (Part 3) will cover the OSHA document, Code of Federal Regulations Requirements, and the interpretations related to emergency fixtures issued by OSHA staff.