Turning Up the Heat in Emergency Fixtures
You have many options when installing emergency fixtures for outdoor applications.
- By Rebecca Geissler
- Oct 01, 2004
IT is entirely possible employees will never need to use emergency drench showers and eyewashes in a facility. That is, if primary protection systems are used effectively and the procedures are well designed. Yet emergency fixtures are the absolutely essential, must-be-there backup equipment in the event that other protection fails. The situation is often critical when emergency showers and eyewashes are needed, so units must be readily available and prepared for immediate use.
Designing a safety system to meet the particular needs of any facility or application is important. It is critical for those exposed to a chemical or other eye and skin hazards to have quick access to a functional drench shower and eyewash unit capable of providing water at an appropriate temperature. Emergency fixtures for outdoor locations, with the wide range of temperature fluctuations involved, are an often-overlooked component in overall safety design. It is likely some, or maybe even all, of a facility?s high-risk processes are located outside; the safety of workers in these locations can not be ignored.
Outdoor applications require emergency fixtures that are specifically designed to function through a range of temperatures, particularly in northern climates. Cold temperatures pose the most significant challenge for fixtures because frozen water in the pipes and valves not only causes them to be inoperable when needed, but can also cause permanent damage. In some locations, it is necessary to protect the water from both freezing and overheating.
There are applications in which a potential hazard is located indoors but the building is unheated. Or environments are temperature controlled but at levels that are near or below freezing. In general, the solutions discussed here are applicable to these situations, as well as to outdoor applications.
Four Solutions for Outdoor Emergencies
According to the ANSI Z358.1 standard, any emergency fixture installed where the potential for freezing exists should be protected from freezing, or freeze-protected equipment should be installed. There are multiple solutions for outdoor applications, all of which comply with this standard.
The types of fixtures we will cover should meet the standard's recommended 0.4 gallons per minute (GPM) minimum flow for eyewash units and a minimum of 20 GPM flow from the showerhead, but it is important always to verify that a specific unit meets these requirements. Following are four different types of emergency fixtures that are designed to withstand Mother Nature's extreme temperatures.
Two types of products fall into the category of traditional frost-proof units: through-wall fixtures and fixtures with buried incoming supply pipes. As the name implies, through-wall fixtures protect pipes from outdoor temperatures by keeping them on the inside of the wall. Other frost-proof fixtures protect pipes containing water by placing them underground, below the frost line. The constraints of a particular application will determine which of these fixtures offers the best solution.
A through-wall fixture can be very practical for outdoor hazards located near a plumbed and temperature-controlled building. This fixture mounts through an external wall, allowing the water supply pipes to be located in an indoor location, while the drench shower and/or eyewash are mounted on the outside wall of a building. The through-wall design protects water in the pipes against both overheating and freezing by keeping the ball valve assemblies internal to the building. This process is augmented with weep valves inside the building that drain any excess water from the outdoor portion of the system after activation.
Some manufacturers offer a shower version and an eyewash version of this product, and combination shower and eyewash units are available. Typically, fixtures can be specified for a range of wall thicknesses. Overall, the through-wall drench shower and eyewash products are versatile fixtures that offer a cost-effective option when there is a plumbed building nearby with a suitable outside wall. When this is not the case, other alternatives must be considered.
Frost-proof units with buried pipes can be more flexible in their placement, although they do require an underground water supply and all pipes that feed the unit must be below the frost line. The fixtures usually can be ordered with a range of bury depths to ensure the supply to the unit is safely below the frost line. Typically, a concrete pad or gravel patch is required for drainage, and eyewash fixtures with bowls also require a system to drain them below the frost line. The ball valves are also underground to prevent water from remaining in the above-ground pipes.
All pipes that might retain water in this emergency fixture are buried underground. This means water in this type of frost-proof system is also protected from heating by the sun. Although this is not the primary application, this system will have the added benefit of some protection from the sun in hot weather. Both types of frost-proof fixtures are appropriate for a wide range of temperature applications.
While frost-proof fixtures are successful for many applications, sometimes a more sophisticated product is required. Heat-traced (cable heated) fixtures are designed specifically for cold weather applications. These fixtures have a heat-trace cable wrapped around the piping that regulates the temperature of the water inside the fixture to avoid freezing or overheating. The pipes are insulated with polyethylene foam, and the entire fixture is wrapped in ABS plastic with the seams sealed for maximum weather protection.
These types of units are well suited for extreme cold. Most units offer a freeze protection valve that ensures continual operation when internal temperatures drop below 35 degrees. The heat-trace shower generally can be supplied from either the top or bottom and requires an electrical source. Standard features and options vary by manufacturer, so it is important to identify those required for a specific application. The heat-traced fixtures offer a more comprehensive option with a wider range of available functional attributes than the standard frost-proof units, and they are priced accordingly.
Polar showers provide a comprehensive option for cold weather applications. Although the price of these units is typically steep, they can be beneficial in the right applications. Polar showers usually offer a heated, insulated enclosure paired up with a local tempered water supply, but they may involve only a heat-traced shower in a heated enclosure. The emergency fixture, usually a combination shower and eyewash, is located inside the enclosure. A user enters the enclosure and is protected from outside conditions when activating the shower or eyewash.
When supplied, the local tempered water system is sized to handle the high water demand of an emergency shower and eyewash activated for a full 15 minutes. The water system may be self-contained with a local tank or be fed by a facility's plumbing system. The correct product for a polar shower application should be selected based on the availability of a plumbed water supply and the optimal method of heating the water in a particular application.
For applications where a little more flexibility is required, portable eyewashes or self-contained products can appease temperature concerns. Several companies market portable units encased in a heater jacket designed to regulate water temperature. Units typically require a 120V AC line. A thermostat regulates the heating of the unit, and often a secondary thermostat is provided to prevent overheating if the main one fails.
It is important to verify any product being considered meets the ANSI specification for portable eyewashes, not personal eyewashes. Portable eyewashes must provide a full 15 minutes of water flow through the eyewash sprayheads and exceed 0.4 gallons per minute. All electrical components used should be UL listed.
Other Key Considerations
The types of fixtures mentioned offer various ways to combat the freezing and heating of the fixtures. It is important to also consider the temperature of the water itself as it is flows out of an emergency drench shower or eyewash.
ANSI Z358.1 recommends that affected areas be flushed for 15 minutes. Water that is too cold can cause user discomfort, while water that is too hot may scald the user. Either situation will limit the time spent flushing the affected surface, which can compromise user safety. As a result, in 1998, the ANSI Z358.1 standard was revised to include a requirement for tempered water.
Heated portable units should maintain water temperature within a safe range, and polar showers provide heating of the water at the site to appropriate temperatures. Other products, including most of the traditional frost-proof ones, the through-walls, and the heat-trace showers and eyewashes require a tepid water supply to the fixture.
For plumbed fixtures, a thermostatic mixing valve can assist in providing the required tempered water. It is important to understand fully the features of the valve selected and to be sure the valve is sized to accommodate the flow of all attached units, should they be simultaneously activated in an emergency.
As a safety feature, most thermostatic mixing valves have a cold water bypass that activates if the hot water supply is interrupted. Generally, flushing with cold water would be preferable to not flushing the affected area at all. In a scenario when cold water supply is cut off, most valves will shut off supply to the unit because the potential for scalding outweighs the benefits of flushing the area.
Finally, a key consideration for outdoor emergency fixtures is an alarm system. This can be very important for outdoor applications because people are more likely to be spread across a larger area, and the person activating the alarm may be the only person in the immediate vicinity. Most manufacturers offer some type of alarm system, such as a horn and indicator light.
When selecting an alarm, carefully evaluate placement. Where possible, it often makes sense to wire the alarm to an inside location. This is easy to do for through-wall fixtures. In other applications, placing the alarm horn and light outdoors is most logical because other outside personnel will respond quickly. In many cases, having an alarm in both locations is the best situation--most alarm systems can accommodate both a local and remote alarm.
Beyond alerting others to respond to an emergency, alarms notify facility staff that a fixture has been used. ANSI requires stay-open ball valves to be used in eyewashes and drench showers. This means once a fixture is activated, it will flow until it is shut off. In the case of a plumbed unit, this could result in significant water waste and/or a situation in which dangerous ice builds up around an external unit. An alarm can protect against this type of vandalism (or possibly even unintentional activation) by alerting others that water is running through the fixture.
Installation Guidelines in Z358.1
When installing fixtures in an outdoor location, it is important to incorporate the guidelines for installation in the ANSI Z358.1 standard. Here are some of the guidelines to keep in mind. Units must be:
- Placed in a well-lighted location within 10 steps of any hazard.
- Easily accessible--not upstairs or behind obstacles.
- Inspected and tested regularly--weekly for plumbed units.
- Supplied with tepid water.
- Designed to accommodate simultaneous activation of all showers/eyewashes.
Preparing for outdoor hazards should be part of a good emergency plan and must be addressed with the appropriate primary protection equipment. But when primary equipment fails or procedures are not followed, it is important to have a solid secondary plan in place. This "plan B" should include eyewash units and drench showers that meet the recommendations of the ANSI Z358.1 standard and take your outdoor environment into account.
Facility inspectors and product manufacturers are good resources to help you find the emergency fixture that is right for your indoor and outdoor applications.
This article originally appeared in the October 2004 issue of Occupational Health & Safety.