Impact Resistance: Protective Eyewear
A look at the standards, and how they compare
By Philip M. Johnson, Honeywell Safety Products.
Background
Historically, impact resistance has been regulated by agencies like FDA since the early 1970s for products furnished through medical and retail channels, such as sunglasses and prescription eyewear. It is simply a drop ball test where a 5/8 inch steel ball is dropped free-fall through a tube from a height of 50 inches onto the lens surface.
For protective eyewear meant for industrial or occupational use, the governing document is ANSI Z87.1, and it has been in existence, through several iterations, for almost 40 years. OSHA in its regulations (see CFR 1910.133) specifically cites Z87.1 as the minimum performance requirement for protective eyewear, effectively giving it the weight of law. Where a hazard assessment in the workplace indicates that eye/face protection is needed, such protection must be provided, and it must comply with this ANSI standard.
Selecting eyewear that meets or exceeds a variety of standards will afford reliable protection against hazards that are present in the workplace.
Originally, Z87.1 also specified a drop-ball test with the difference being an increase in the ball diameter to 1 inch for most lens types. Glass lenses at least 3mm (1/8 inch) thick and properly treated, could meet this test. Plastic lenses also were required to pass a penetration test wherein a weighted needle is dropped 50 inches onto the product. The lens cannot fracture or be pierced.
In 1989, the standard was upgraded to add elevated impact and lens retention tests in addition to the basic drop ball requirement. Technology, articularly the advent of polycarbonate plastic as a high performance lens material, drove this change. It recognized that more robust products could be designed which would be a benefit to those needing to wear protective eyewear where significant impact hazards existed.
ANSI Z87.1 Tests
The current edition of the standard is Z87.1-2003. Lenses in all protectors must at a minimum meet a basic impact requirement: the 1 inch drop ball test. Models can achieve “high” impact levels indicating elevated performance. The following “high” impact tests apply to lenses, as well as to the frames or product housing:
• A lens retention test is conducted via a “high mass” impact. A pointed 500 gm (1.1 lb) projectile is dropped 50 inches onto the complete protector mounted on a headform. No pieces can break free from the inside of the protector, the lens cannot fracture, and the lens must remain in the frame or product housing. This test is a good measure of the product’s strength, simulating a blow such as from a tool that slips from the work surface or when the lens collides with stationary objects.
• A high velocity test is conducted, at 20 specified impact points, where the projectile is a ¼ inch steel ball traveling at specific speeds depending upon the type of protector. For spectacles, the velocity is 150 ft/sec or 102 mph. The pass/fail criteria are the same as for the high mass test, plus no contact with the eye of the headform is permitted through deflection of the lens. This is meant to simulate particles that would be encountered in grinding, chipping, machining or other such operations. In the United States, compliance with the standard is self-certified, based on test results generated by the manufacturer as part of its initial design and ongoing Quality Control procedures. No independent certification is required. Products meeting the basic impact standard shall be marked “Z87” on all major components. Those products which pass the “high” impact tests listed above can carry a “Z87+” marking on the lens(es).
Global Impact Standards
Other standards exist for assessing the performance of protective eye and face products, including requirements for impact resistance. While the test procedures may differ somewhat from region to region, the intent is to measure impact strength of the entire protector, and to set criteria for minimum levels of performance. However, one test that has been harmonized across many key regional standards is the high velocity test conducted with a ¼ inch steel ball.
Canada – CSA Z94.3-2002
In Canada, the pertinent standard is Z94.3-2002 developed by the Canadian Standards Association (CSA). Impact performance is assessed with the ¼ inch steel ball traveling at 46.5 m/sec or 152 ft/sec. Impact points that must be evaluated include the midpoint of the protector, as well as multiple frontal and lateral locations, some of which duplicate those assessed for Z87.1. Other points are selected to test areas of the protector that could be vulnerable to impact such as where the lens attaches to the frame, where the temple pieces attach to the frame or where thin material sections are present. These sites will vary with the design of the product, providing a thorough evaluation of its ability to provide protection. Failure criteria are
equivalent to those in ANSI Z87.1.
A manufacturer may test the products on its own, or as an option may submit products to CSA International to have them tested and thus “third party” certified as being in compliance. In the latter case, a product in conformance may be marked with the CSA logo, a recognized Quality Mark in Canada. It can be compared to marks such as Underwriter’s Laboratory (UL). Certain manufacturers, such as Bacou-Dalloz (now Honeywell Safety Products formerly Sperian Protection), are authorized by CSA International to test products on its behalf because their laboratories have been audited to a strict set of guidelines. This allows the CSA logo to be marked on the product after review and acceptance of the test results by CSA.
Europe – EN 166 – 2001
In Europe, performance and testing of protective eyewear is governed by a suite of standards. The fundamental performance requirements are detailed in EN 166-2001. Spectacles claimed to meet high levels of impact resistance are subjected to a 6mm ball traveling at a minimum velocity of 45m/sec (147.5 ft/sec). Two basic impact areas are specified, and they are described as 20mm circles centered directly in front of the eye, and at 90 degrees to the protector centered on the back corner of the eyeball. Failure modes are similar to U.S.and Canadian standards, and the frame components
may not exhibit any fractures nor become detached. In Europe, third party testing is required of all eyewear employed for industrial protection. A qualified outside party conducts product testing and reviews documentation pertaining to materials of construction and quality testing. Upon approval, specific markings are applied to the products. These include the letter “F” on the lens indicating high speed particle protection, and the universally recognized “CE” mark.
Australia – AS/NZS 1337 – 1992
The Australian standard specifies several elevated impact resistance levels. The level for high performance spectacles employs a 6.35mm (1/4 inch) ball traveling at 40 meters/sec. (131 ft/sec). The impact points are equivalent to those specified in Europe, as are the criteria for pass/fail. Products certified for use in Australia and New Zealand are subject to independent compliance testing and certification. In addition, the factory producing the eyewear must be audited and must receive a distinct factory license indicating its status as an approved manufacturing facility. The lens will be marked with the letter “I”, and the product will have the Standards Australia mark applied.
Military Ballistic Performance
The various branches of the U.S. military have recognized for many years that eye injuries are an inevitable by-product of their many activities. This is true not just in combat situations, but in a variety of support activities on flight lines, in maintenance settings and in special operations. Protection is required for ballistic impact protection, chemical protection and for radiation protection from sunlight and high energy lasers. Over the past 5 to 6 years, the U. S. Army particularly has championed the use of high performance spectacles as general issue gear for all deployed personnel. A small group of products including Genesis® spectacles have been approved and have seen extensive use in Afghanistan and Iraq where improvised explosive devices (IEDs) are a constant threat.
The Army specifies that protective eyewear comply with Military Standard 662 which outlines a number of ballistic fragmentation tests for different classes of products. The test consists of firing a special shrapnel simulating projectile at a specified velocity. The fragment is cylindrical and has an angled face that will burrow into the product. For ballistic spectacles, the fragment is 0.15 caliber and the velocity of the projectile is 650 +/- 10 ft/sec (440 mph). In this case, the test protocol specified is as “V0” (V-Zero). This means that no (zero) impact failures are allowed at the velocity
specified. The spectacle is impacted once, at a point coinciding with the center of either the left or right eye. The lens cannot fracture, nor can the projectile penetrate to the eye. The impact energy of this test is about 7 times that of a ¼ inch steel ball traveling at 150 ft/sec.
One may wonder if this test is too extreme for eyewear meant primarily for industrial use. The way to look at this is the added level of protection and security afforded by products offering V0 impact performance. For example, the obvious impact hazard may be particulate generated by an operation such as grinding. The less obvious threat is the explosion of the grinding wheel which can send shards of material flying at speeds considerably higher than ANSI standards test. While many spectacles can meet the minimum performance of industry standards, higher performing products offer better protection to give you a fighting chance in case of unforeseen accidents. (No product is unbreakable or impenetrable given high enough impact energy, and additional protection such as goggles or faceshields may be necessary based on the workplace hazard assessment).
Additional protection will make sense, and certainly be appreciated, in other applications including EMS, law enforcement and homeland security. The proper combination of design, materials and controlled manufacturing processes will yield superior impact protection in products that are at the same time stylish, comfortable and a great value given the level of protection delivered.
Selecting eyewear that meets or exceeds a variety of standards will afford reliable protection against hazards that are present in the workplace. The eyewear will have been rigorously tested for impact resistance as well as other requirements, including optical performance and protection from radiation where needed. These products can be relied upon for hours of safe and secure use in most industrial and occupational settings.
