Let’s approach the question of service and shelf life by summarizing three characteristics that all end users should understand regarding CPC use and limitations: design, performance, and intended service life. Design characteristics indicate how the item conforms to the wearer. These generally include full-body and partial-body garments, gloves, footwear, and face and eye protection. These design features also differentiate items of the same type: for example, totally encapsulating chemical protective suits (level “A”) and splash suits (non-encapsulating level “B”). Materials like rubber and plastics also serve to distinguish design features such as elasticity and weight.

Performance characteristics can refer to general or specific criteria about the item’s ability to provide a barrier between the wearer and injurious particulates, liquids, vapors, and gases. Specific classification is related to barrier performance.

Service life characteristics, including “shelf life,” indicate the useful life of the item relative to users’ expectations. Three general classes include single-use/disposable (which indicates equipment that is relatively inexpensive and intended for replacement after use), limited use (may not be suitable for hard physical conditions or is degraded by use and maintenance), and reusable (can be continually cleaned and maintained for acceptable performance).

With these characteristics in mind, let’s shift our focus to service and shelf life. Although the terms “service life” and “shelf life” aren’t exactly interchangeable, they’re intertwined when it comes to a discussion of PPE. Service life basically means the elapsed time between delivery of an item in anticipation of use and its permanent removal from service or anticipated use, while shelf life refers to the amount of time the item may remain in storage before being placed into use. In the second case, the item may be subject to material degradation due to heat, ozone, or the effects of aging, all of which can be impacted by factors such as storage practices and environmental conditions. For our purposes, then, we’ll simply refer to service life for the rest of this discussion. Consider service life as a function of durability, ease of re-servicing, and life cycle cost. Durability is a measure of how long an item performs acceptably under the conditions of care, use, and maintenance. Product durability is often estimated on the basis of actual field experience; it is largely a matter of how well the item resists physical changes, such as rips, tears, coating cracks, discoloration, or degraded functionality. Ease of re-servicing essentially refers to the level of effort needed for post-use repair (or decontamination) and routine maintenance or testing. Decontamination costs (both money and time) are the most significant re-servicing aspect, and often the main reason to favor disposable over reusable items. Life cycle costs include purchase cost, labor cost (selection, inspection, storage, cleaning, maintenance, and repair), and disposal fees for used or contaminated items. Following are examples of common service-life concerns for PPE:

In my workplace, it’s usually easy to find a box of thin nitrile or latex exam gloves. This entire class of glove type is too thin to meet permeation testing criteria, and they aren’t suitable to protect the user against chemical exposures.

However, under light-duty conditions, they’re inexpensive and an obvious single-use choice for work involving incidental contact or surface contaminants. They don’t stand up to hard physical abuse, but they’re convenient and can be doubled up when needed. However, if the only box of gloves available to you is dispensing shredded gloves, then the service-life question is overdue and the time has come to get a new box. The manufacturing date might be shown on the box, or maybe you can track it down using indicators such as the lot or batch number.

There are two types of battery for powered air-purifying respirators: rechargeable batteries, which include nickel cadmium, nickel-metal hydride, and lithium ion; or non-rechargeable, single-use, disposable batteries, which include alkaline, lithium-sulfur dioxide, or lithium manganese oxide. Under room-temperature conditions, the service life of non-rechargeable cylindrical batteries varies, and so can the manufacturer’s information. One source listed the service lives as 5–10 years for alkaline batteries, 3–5 years for carbon zinc, and 10–15 years for lithium, while another listed those shelf lives as 7, 3, and 7–10 years, respectively.

Elevated temperatures will shorten service life, and many battery designs incorporate protective circuits that provide a low or slow voltage drain; the equipment electronics usually include an integral battery indictor. Otherwise, the simplest and most effective way to check is a “loaded voltmeter” battery tester; unloaded testers can be unreliable, and no tester will provide a reliable run-time estimate. Rechargeable batteries have limited lives, whether in storage or use, and there are differences between manufacturers of the same battery type. Lithium-ion batteries slowly self-discharge whether in storage or use, and the user must be aware of current charge status and the manufacturer’s charging instructions.

Like other products, the design and construction of hard hats has changed, and the choices available to consumers have greatly expanded to include non-traditional styles (cowboy hats) and designs (flags and sports teams). What can be overlooked is that the suspension and hat body are two separate components with different service lives. The interior of polymer hats typically displays a raised mark indicating the date of manufacture, while the effective “service life” is often based on the date it was issued to the wearer. Suspension components may not have such a mark. Manufacturers often recommend a service life of five years for hats and twelve months for suspension components.

There was a time when these items were manufactured primarily of steel or aluminum, and their service life was very limited. Carbon composite cylinders were first approved for sale in the United States in the mid-1990s and are commercially available in capacities up to 4500 psi. The change in materials of construction has significantly impacted design and service life. These items are manufactured (and maintained) according to Department of Transportation specifications, and are now available with design lives of fifteen to thirty years. Extended-life cylinders are manufactured with additional carbon fiber, have more stringent testing requirements, and are slightly heavier than their “unextended” counterparts. Regardless of capacity, cylinders must be re-qualified through hydrostatic testing at least every five years; check the manufacturer’s literature or website for details.

In the relatively early days of hazmat teams, level “A” garments were often constructed of rubberized materials, and a lot of effort was put into “plugging and patching” these high-dollar items due to budget constraints. The construction of modern TECP garments is a different matter altogether. In these garments, we find laminate barriers (supporting fabrics, polymers, and so on) combined with the materials found in gloves, flaps, zippers, and face shields. The result is a blend of materials for which service life information may or may not be available. For instance, accelerated aging tests by one manufacturer indicate that some proprietary fabrics have a service life well over five years in the absence of ultraviolet and temperatures greater than 40°C, and field studies suggest the fabrics may be stable for periods of 10 years or more. In this case, the manufacturer recommends removing or repurposing the garment at the end of five years of service.

Another manufacturer found that 20-year-old protective fabric withstood the ASTM F1001 test of 21 chemicals with no breakthrough in >480 minutes. Here, they recommended removal or repurposing based on the users’ assessment of visual (and pressure testing, when applicable) inspection results. A third manufacturer recommends a 10-year shelf life based on a combination of packaging practices, appropriate storage environment, and the absence of sunlight or strong light sources. As the end users, then, it’s left to us to sort through these technical differences among garment manufacturers. In no particular order, we can take the following actions to proactively manage PPE service life: • Characterize the anticipated conditions of field use. • Match product specifications to the anticipated conditions of use. • Buy in bulk only when it makes sense to do so. • Arrange storage areas to make it as easy as possible to inspect and test items. • Consider marking stored packages with receipt dates. • Be realistic about post-purchase costs of maintenance, service, testing, and inspection, and whether the needed resources are available. • Implement a schedule for routine inspection, cleaning, and maintenance. Service life is always positively influenced by routine attention. • Keep manuals and instruction sheets for future reference. • Be scrupulous about performing pre-use inspections on all PPE. • Set clear policy expectations concerning PPE management. • Provide user education and training.

Ultimately, it is left to the employer to decide whether protective clothing and equipment is fit for service. For you, the IH, this means that “shelf life” and “service life” are simply elements of a properly designed and implemented PPE program.