Glove design relies on air bladder in Stevens Urethane, minimising health risks from impact, vibration and repetitive motion.
A new style of work glove introduced by Impacto Protective Products of Belleville, Ontario, relies on a unique air bladder system made with Stevens Urethane thermoplastic polyurethane (TPU) to protect workers from impact, vibration and repetitive motion injuries.
The Impacto AirGlove incorporates a patented Antivib air bladder developed by ErgoAirSM of Las Vegas, Nevada. This absorbs and dissipates vibrations at both high and low frequencies, protecting workers who frequently use pneumatic drills, jackhammers and other power tools.
These gloves meet European standards for impact and vibration, and anticipated ergonomic standards proposed by OSHA, the US Organizational Safety and Health Authority.
Regular exposure to vibration can cause serious medical problems, such as a condition called 'white fingers', a breakdown of the nervous system where the fingers blanch and sensation is lost in the hand and fingers.
Vibration has also been shown to cause or contribute to other hand/wrist medical problems such as carpal tunnel syndrome. The AntiVib air bladder used in the glove was developed by Dr. Douglas Reynolds, PhD, and Dr.
Thomas Jetzer, MD, MPH, founders of ErgoAir.
The company worked with Impacto and Dielectrics Industries of Chicopee, Massachusetts, to transform the concept of a vibration-reducing bladder into a glove that would meet the requirements of ISO Standard 10819 to be classified as an anti-vibration glove.
Dielectrics Industries contributed expertise in air bladder technology and manufacturing, while Impacto was already an established supplier of industrial safety products.
After nearly four years in development, the resulting AirGlove passed three different anti-vibration tests: European CEN certification as an antivibration glove at Delta Acoustics and Vibration in Lyngby, Denmark, and the Berufsgenossenschaftliches Institut fur Arbeitssicherheit (BIA) in Sankt Augustin, Germany, the European laboratory responsible for developing test procedures for ISO Standard 10819; and also at the Center for Mechanical and Environmental Systems Technology (CMEST) at the University of Nevada.
The AirGlove, which was introduced to the market in early-1998, is the only product to have been tested at the BIA that has met the requirements of ISO Standard 10819 to be certified as an antivibration glove. "When ErgoAir approached us with the concept of using a TPU air bladder to attenuate vibration, we were very interested in incorporating it into our gloves," says Ed Lehtinen, president of Impacto.
"The air provides better protection than traditional materials and the TPU gives us a thinner product, lighter weight, with better flexibility.
It is not only superior in terms of dissipating vibration, but it is also a more practical product from a usage standpoint." Traditional anti-vibration gloves were far from ideal.
At issue were both the frequency range the gloves could dissipate, and their weight and practicality.
Many such gloves use visco-elastic polymers that are bulky and uncomfortable to wear.
In addition, most of these visco-elastic polymers are ineffective in reducing vibration to the hands.
With the TPU-based anti-vibration bladder system, the AirGlove effectively reduces vibration to the hands, it is nearly weightless and is comfortable to wear.
"AirGloves dissipate between 40 and 60% of vibration depending upon the frequencies," said ErgoAir's Dr.
Tom Jetzer.
"You are not totally eliminating vibration.
However you are prolonging the time a person can use a tool without causing a medical problem." According to Steve Wiater, project manager at Dielectrics Industries, TPU was chosen for its strength, flexibility and temperature resistance.
"We needed a material that could withstand extreme temperature ranges and take a lot of vibration over a long period of time," says Wiater. "Also, tensile strength was important.
We wanted a very thin material, so the bladder would be streamlined and comfortable, not bulky.
Given these criteria, TPU was the best choice to meet all our needs.
We are able to use a very thin film, only 0.15-0.18 mm (6 or 7 mil), yet still be very strong.
Other materials would have to be twice as thick to provide the same performance." Wiater notes that the pump in the air bladder provides 0.7-0.85 kg/cm2 (10-12 psi) pressure and the TPU burst strength falls well within that range.
The AirGlove's AntiVib system consists of a flexible hand-shaped bladder made from 0.15 mm (6 mil) Stevens Urethane, die cut and radio-frequency (RF) sealed, and designed with a quilted pattern of weld points and weld lines corresponding to the flex lines of the hand.
The bladder is constructed with interconnected chambers which, when a tool or other object is gripped, allow the pressure to force air out of the slightly thicker palm and into the finger chambers, for consistent thickness and protection throughout the glove.
The bladder includes a pump and valve system that allows the user to inflate it by depressing a bulb on the back of the glove.
Some 50-60 pump actions are needed to fully inflate the bladder for maximum protection, with daily touch-up pumps to replenish air lost through osmosis or slow leakage through the valve.
Correct inflation is critical, because if air is lost and not replaced, protection is reduced accordingly.
"The lightness and flexibility of TPU are key to the performance of the bladder," adds Dr.
Reynolds of ErgoAir.
"It is so thin that it's almost not there, which makes it more comfortable to the wearer.
It creates a cushion with no interference with the tactile feel in the glove." Stevens Urethane is a recognised leader in the design and manufacture of polyurethane film, sheet and tubing, sold under the Stevens brand name.
Stevens film and sheet can be manufactured in thicknesses from 0.025mm to 3.2mm (0.001 to 0.125in) and in widths from 12.7cm (5in).
Tensile strength up to 700kg/cm2 (10,000psi) assures reliability and durability over a long working life; urethane film and sheet can elongate significantly and still return to its original dimension with no loss of 'memory'.
Stevens Urethane is available in hardnesses from 75 to 95 Shore A, and in a range of standard and custom colours.
Various opacities and surface textures are also available.
It can be custom formulated to meet specific application requirements.
Based in Holyoke, Massachusetts, Stevens Urethane manufactures a full range of high-performance urethanes for use in a wide variety of "can't fail" applications for consumer, medical, commercial, and industrial markets.
Stevens Urethane is the only company in the world to offer urethane in blown film, extruded sheet, tubing, cord and profile form.
