July 11, 2017
Verifying a life jacket’s life-saving ability is important. Will it hold up to the elements? Maintain a person’s buoyancy in an emergency? To answer these questions and more, UL performs tests to certify the performance and functionality of life jackets at its laboratory, which includes a “test tank,” in Research Triangle Park, North Carolina.
How do they test life jackets and what types of testing is performed? Chris James, UL’s Principal Engineer for Flotation Devices, explained the testing procedure in a recent interview with Inside UL. Let’s dive into the world of life jacket testing to learn what goes into certifying the performance of life-saving equipment.
The test lab places the testing types into two different categories. Category one is in-water performance/human subject testing and category two is mechanical testing. Some of the tests conducted are listed below:
In-water performance/human subject tests
- Recruit test subjects: To test life jackets, the lab needs people willing to get wet. As people come in different shapes and sizes, UL recruits a variety of test subjects to help evaluate life jackets—different ages, weights and chest sizes.
- Donning Test: the Donning Test validates that the device being tested is simple enough to thoroughly don, or put on, within 60 seconds from the start of the test. An adult is allowed to assist children 12 years of age or younger. This test tries to resemble an emergency situation where one has to abandon ship by either a lifeboat or direct entry into the water. “A manufacturer can design a very innovative device with all the bells and whistles, but in an emergency situation, if it takes a user five minutes to put the device on, the lifesaving characteristics of the device will be ineffective,” says James.
- Water Entry Test: The water entry test evaluates the overall integrity of the device to confirm that the device doesn’t harm the user. Subjects enter the water from three different heights--one meter, three meters and four-and-a-half meters based on the performance level of the device. “What we’re validating during this test is that the device does not come off or injure the user when the subject impacts the water,” according to James. Additionally, the test lab needs to determine if the force of entry damages the life jacket as there are situations where the weight/size of the user along with impact force could rupture a seam because these devices are fabric garments which are commonly sewn together with thread. “Say someone weighs 300 pounds and this person jumps from a distance of 4.5 meters above the water. Just the impact of that subject with the device on can sometimes damage the device.”
- Flotation Stability Tests-Freeboard, Face-plane and Torso: The Freeboard Test measures the subject's lowest point of respiration from the surface of the water. While the Face-plane Test measures the amount of head support and the Torso Test measures the amount of body angle, both tests determine the flotation angle of the subject. The importance of these tests is to validate that the user does not need to perform additional actions to keep their airways above water and spot potential rescuers, as such actions will tend to require the user to expend much-needed energy if they find themselves in need of rescue.
- Turning Tests: Two evaluations are performed to determine the turning ability of a life jacket; will it right an unconscious wearer from a face-down to face-up position; and can a conscious subject quickly turn themselves from a face-down to a face-up position? Based on the type of device, the test is performed in one of the two following manners:
- The subject is placed in a horizontal position that resembles a face-down unconscious user. The UL tester will hold the subject's feet until his/her face is in the water and then quickly release the hold to demonstrate the turning capability of the device.
- The subject is instructed to perform three slow breaststrokes and simulate a face-down unconscious user at the conclusion of the third breaststroke.
It is also very important to validate that the device has adequate buoyancy distribution so that a conscious user can turn from a face-down to maintained face-up position. This is done by having the subject place themselves in a face-down position. The UL tester will then have the subject turn themselves. The subject must be able to turn themselves within five seconds.
- Placement Security Test: Life jackets can shift on the body while floating, swimming and conducting activities in the water, leading to the possible removal of the device. In some cases, shifting of the life jacket could block the airways or impede a person’s line of sight. The test lab instructs the subject to perform three jumping jack motions in the water to induce upward shifting of the device. After the motions have been completed, the distance between the top of the user’s shoulder and the shoulder of the device is measured when any portion of the foam is forward of the ear and above the lowest portion of the mouth or obstructs vision.
- H.E.L.P Test: An extended water immersion could lead to heat loss and hypothermia. To protect the body’s three major areas of heat loss (groin, head/neck and rib cage/armpits, test subjects are asked to assume the Heat Escape
[caption id="attachment_28784" align="alignright" width="250"]Arms and knees tucked close to the body to help conserve heat.[/caption]
Lessening Position (H.E.L.P). The purpose of this test is to assess if the device will allow the subject to maintain the position.
- Water Emergence Test: Users may have to rescue themselves by exiting the water, but some devices may not allow the water to drain quickly from the life jacket, making it difficult to pull one’s self up from the water. The Water Emergence Test evaluates the subject’s ability to exit the water onto either a life raft or an elevated platform.
- Rearming/Repacking Test: For inflatable devices only. Once an inflatable has been used, the device needs to be rearmed and repacked. An untimed event, the subject must be able to correctly rearm and repack the device per the manufacturer's instructions.
View the video to see how we test in the lab
Mechanical testing is the process of applying forces, pressures, heat pressures, heat or similar stressors to verify a product’s performance and design. With life jackets, UL wants to verify its ruggedness and ability to hold up to simulated stressors that could interfere with the life jacket’s ability to perform during an emergency.
- Buoyancy Test: Without buoyancy, a life jacket cannot perform its primary function--to save lives. The buoyancy test confirms the buoyancy level of the device as defined by the regulatory requirement, i.e., the United States Coast Guard (USCG) or Transport Canada (TC). The amount of required buoyancy varies due to the intended use, environment, classified user group and type of device. The device is placed under 50 mm of water and maintained for 24 or 48 hours (based on the performance level of the device). Before the test can start, the device is agitated to remove all entrapped air from the device. At the conclusion of the test, the buoyancy is calculated by taking into account the temperature of the water and the atmospheric pressure.
- Overpressure Test: We all know what could happen if an inflatable device becomes over-inflated—pop! Unlike inherently buoyant devices, if an inflatable device is compromised, it will lose 100 percent of its buoyancy. This test validates the devices seams and overall integrity by applying an overpressure to the device.
- Tensile Test: What if a person has to be pulled out of the water by the webbing, buckles or shoulders of his/her life jacket? Is it robust enough to withstand the force? A tensile test determines the life jacket’s overall strength and is used to evaluate the durability of its webbing, fabric, thread, hardware, seams, inflation systems and shoulder constructions.
- Rotating Shock Bin Test: A device is placed into a rectangular shaped box (shock bin) and rotated for approximately 25 minutes (6 revolutions per minute). This test recreates the possible damages that could occur when a life jacket is being stored or relocated. After the test, the device is examined for damage.
- Inadvertent Inflation Test: For inflatable life jackets, an occasional water splash or rain storm could lead to the automatic inflation of the device. This test evaluates if the cover for an automatic inflatable adequately protects the inflation system from inadvertently inflating. This test is conducted for one hour. If the device inflates, it is considered a failure.
- Puncture Resistance Test: Water can be naturally filled with debris that could puncture and deflate an inflatable life jacket. This test evaluates the fabric strength and seams of a fully inflated life jacket and its ability to withstand a pointed probe.
As stated earlier, the list of tests is not all-inclusive. However, the performance verification through UL’s comprehensive evaluations—in-water performance and mechanical testing—helps drive device consistency, design quality and helps provide peace of mind for water lovers around the world. But, UL could run a thousand tests and have it mean nothing if water enthusiasts do not wear a life jacket when on or near the water.