As unimpressive as it sounds, Kevlar® is merely just a super-strong type of plastic.

Scientifically known as “poly-para-phenelyne-terephthalamide”, Kevlar® is a para-aramid fiber, and is a member of the synthetic aromatic polyamide family, similar to Nomex®.

The chemical structures of Kevlar® and Nomex® are quite similar, as they both contain many identical molecules which are tightly connected together in long ring-like chains. These run inside, and parallel to the fibers of Kevlar, similar to how rebar is positioned in reinforced concrete.

The chains are then cross-linked with hydrogen bonds in order to form long, thick fibers. This is done by forcing them through a sleeve during a very hot, concentrated state. These fibers are then woven into super stiff mats or sheets, which is what gives the material its super high-tensile strength.

Tensile strength is basically the resistance offered by a material against a force to prevent elongation.

The tensile strength of Kevlar® is about 8 times more than that of a steel wire. Surprisingly it is relatively light in weight for being so strong.

Another benefit of Kevlar® is that it has a very high resistance to both hot and cold temperatures.  It is probably one of the only ‘plastics’ that does not melt or even expand when heated, nor does it become brittle and break at very cold temperatures. Kevlar® is also highly resistant to any kind of abrasions.

Kevlar® and all of its wondrous properties were discovered in the early 1960’s by a US chemist at the DuPont™ chemical company named Stephanie Kwolek (1923-2014). She earned US Patent 3,287,323 for her invention, along with Paul Morgan, in 1966.

Kevlar®, introduced in 1971, was originally developed as a lightweight replacement for steel bracing in vehicle tires, although currently it is used in many things including gloves and even bulletproof vests.

References

Woodford, Chris. (2008/2019) Kevlar. Retrieved from https://www.explainthatstuff.com/kevlar.html. [Accessed (2019-10-26)]

DuPont de Nemous. (2019) DuPont™ Kevlar® Properties. Retrieved from https://www.dupont.com/products-and-services/fabrics-fibers-nonwovens/fibers/articles/kevlar-properties.html. [Accessed (2019-10-26)]

TeamScience ABC. [((2017-July-10) Updated (2019-Oct-19)] What is Kevlar? Why are Kevlar vests bulletproof?. Retrieved from https://www.scienceabc.com/innovation/what-is-kevlar-material-clothing-why-kevlar-armor-vests-bulletproof.html. [Accessed (2019-10-26)]

If you’ve ever wondered how a Self-Retracting Lifeline (SRL) works, you’ve come to the right place.

Self-Retracting Lifelines function in a way that is similar to how the seatbelt in your car does. When a certain level of force or speed is attained, a locking mechanism is activated. This prevents and further length of the lifeline cable or webbing from extracting or becoming unwound.

Just like with a seatbelt, if you were to steadily pull the on the lifeline cable, you would be able to pull it out as far as it will go. However, if you were to try pulling on it with a very quick tug, if would only go so far before it stops.

There are a number of parts that make up the SRL.

The housing may be either a plastic or metal enclosure. Inside this enclosure is where you will find the locking mechanism, the drum, and the shaft.

The lifeline cable or webbing is wound onto the drum.

In the center of the drum, there is a metal rod known as the shaft. This allows the drum to rotate to either unwind, or retract.

The locking mechanism is a motor spring that keeps tension on the lifeline when it is unwound, as well as the lifeline itself.

The lifeline cable or webbing is usually fitted with a snap-hook at the end for attachment purposes.

The word “retracting” can be somewhat misleading as some may think that the cable will automatically pull you back if you were to fall. But this is not the case.

Whatever amount of the lifeline cable that is already played or pulled out will remain that way. It doesn’t just wind back up to pull you in.

There are actually two different classes of SRL’s; Class “A”, and Class “B”.

A Class “A” SRL has a maximum arrest distance of 24 inches, whereas a Class “B” SRL has a maximum arrest distance of 54 inches.

The maximum arrest distance is the length, in inches, that the SRL will allow the lifeline to extend or unravel before the locking mechanism engages.

In order for the SRL to properly protect you from a possible fall is to anchor it at the height of your harness. This is typically where the D-ring is located.

Taking care of your SRL is also extremely important. Any amount of dirt, grease, or any other materials that may have built up on, or coated the lifeline, or even gotten inside the casing, could cause the SRL to not function properly.

Also, using the wrong type of cleaning agent could even be as detrimental as not maintaining the equipment at all. Certain chemicals can damage or ‘eat away’ at the lifeline, and even cause the parts inside the housing to malfunction. Always follow the manufacturer’s instructions when cleaning your SRL.

Those numbers and letters stamped onto your work gloves are very important. They indicate the different levels of protection the gloves provide.

Here’s a chart that will hopefully help translate what those markings actually mean:

CUT LEVEL	WELL SUITED FOR….
A	Light material handling, and small parts assembly without sharp edges
B	Packaging, warehouse, light duty general purpose
C	Light duty metal handling, metal stamping, HVAC, light duty glass handling, plastics, material handling
D	Light duty metal handling, appliance manufacturing, bottle and light glass handling, canning, drywalling, electrical, carpet insulation, HVAC
E	Metal stamping, sheet metal handling, glass handling, automotive assembly
F	Heavy duty metal stamping, metal recycling, food processing, pulp and paper

**This is to be used as a general guideline and is for informational purposes only. **

By being able to understand what those markings mean, will hopefully help you to determine the level of protection your gloves provide.

Have you ever wondered what those symbols on your safety boots or shoes mean?

The Canadian Standards Association (CSA) sets out the specific safety criteria for all safety footwear and apparel purchased in Canada. The symbols and codes used on safety footwear are reflective of the labelling system established by the CSA. These are all published in CSA Standard Z195.

Here is a breakdown of what those labels mean:

• Grade 0 – there is no steel-toe cap or toe protection.

• Grade 1 – the footwear provides sole puncture protection and toe protection with an impact resistance of 125 joules (approx. 13kg) – This is indicated by a Green Triangle.

• Grade 2 – the footwear provides sole puncture protection and toe protection with an impact resistance of 90 joules (approx.9.2kg) – This is indicated by a Yellow Triangle.

• Electric Shock Resistant – the footwear provides protection in and environment where live electrical conductors can occur. This is indicated with a White Triangle with the Ω (capital omega symbol), being the symbol for ohms of electrical resistance.

• Static Dissipative – the footwear is capable of dissipating an electrostatic charge in a controlled manner. This is indicated by a Yellow Rectangle with the Green Letters “SD”, a grounding symbol (), and the CSA symbol.

• Electrically Conductive – the footwear provides protection where low-power electrical charges can be a hazard. This is indicated by a Red Rectangle with a black letter “C”, a grounding symbol ( ), and the CSA symbol.

• Chainsaw Protective – the footwear provides protection when using a chainsaw. This is indicated by a White Label with a Green Fir Tree symbol and the CSA symbol.

• Blue Square with the CSA symbol indicates that the footwear is Grade 1 Protective Toe only, with no sole puncture protection.

In addition to a colored symbol, you may also see a 5-digit alphanumeric code inside your safety shoe or boot.

• “1”, “2”, or “0”

A “1” indicates Grade 1 toe protection.

A “2” indicates Grade 2 toe protection.

A “0” indicates no toe protection.

• “P” or “0”

A “P” indicates if the boot protects the arches of your foot from punctures.

A “0” indicates no protection.

• “M” or “0”

An “M” will indicate if the boot provides metatarsus protection against shocks and collisions.

A “0” indicates no protection.

• “E”, “S”, “C” or “0”

An “E” indicates resistance from electrical shocks.

An “S” indicates it can disperse electricity.

A “C” indicates it conducts electricity.

A “0” indicates no electrical protection.

• “X” or “0”

An “X” will indicate if it provides protection from chainsaws.

A “0” indicates no chainsaw protection.

For example, if you see “1 P M 0 X”, it would indicate that your safety footwear has Grade 1 toe protection, and will protect your arches from punctures, along with protecting your feet from collisions, and chainsaws. However, they don’t provide any electrical protection.

Do you ever find yourself wondering what type of job would require which class of Hi-Viz Safety Apparel?

Here are some examples that may be helpful:

High Risk: Class 2 for daytime, Class 3 for low-light conditions.

High Risk Situation Examples:

• Vehicles travelling more that 80 km/h (50 mph)
• Workers on foot and vehicle operators with high task loads that clearly place the worker in danger
• Situations where a workers’ full range of body motions must be visible from at least 390 m (1,280 ft) away

Job Examples:

• Roadway construction workers
• Utility workers
• Survey crews
• Emergency responders
• Road assistance/Courtesy patrols
• Flagging crews
• Towing operators

Medium Risk: Class 2 or 3 based on certain conditions.

Medium Risk Situation Examples:

• Vehicles or equipment travelling between 40-80 km/h (25-50 mph)
• Workers who require greater visibility under inclement weather conditions or low light
• When work backgrounds are complex
• When a workers’ tasks require their attention to be diverted from approaching vehicle traffic
• When workers are performing tasks in or near flowing traffic

Job Examples:

• Roadway construction, utility, forestry or railway workers
• Utility workers
• Survey crews
• School crossing guards
• Parking and/or toll gate workers
• Airport baggage handlers and ground crews
• Emergency response personnel
• Members of law enforcement
• Accident site investigators

Low Risk: Class 2, Class 1 under certain conditions.

Low Risk Situation Examples:

• Workers in activities that permit full and undivided attention to approaching traffic
• When there is ample separation between the worker on foot and the traffic
• When work backgrounds are not complex, allowing for optimal visibility
• When vehicles are moving slowly (less than 40 km/h or 25mph)
• When a workers’ attention is diverted from approaching traffic

Job Examples:

• Directing vehicle operators to parking or service locations
• Retrieving shopping carts in parking lots
• Warehouse operations
• “Right-of-Way” or sidewalk maintenance workers
• Shipping/Receiving jobs

We hope this helps to clarify things a little. But please remember that these are just some examples and are for informational purposes only. If you are unclear what class of safety apparel you need for your specific work duties, please contact your employer.

As a kid, I remember having Velcro® shoes for gym class, because I just couldn’t get my little fingers to tie those tricky shoelaces quick enough. I always thought that Velcro® was pretty neat.

But what I didn’t know was, that Velcro® is a type of “hook-and-loop” fastener whose design was inspired by a burdock burr seed.

Burdock seeds (or burrs), are those prickly little things that are notorious for sticking to clothes and animal fur when hiking.

In 1941, a Swiss electrical engineer named George de Mestral, was inspired by how these burrs had managed to stick to his coat, and his dog, when walking in the woods.  He called his invention “Velcro®”, which is a combination of the French words ‘velour’ (velvet), and ‘crochet’ (hook).

If you were to inspect the burdock burr, you would find that it contains hundreds of tiny “hooks.” De Mestral spent years investigating the burr’s properties and eventually translated those hooking and looping functions into fabrics and created what is known as “hook-and-loop.” However, the subsequent process of recreating this burr-like product to what it is today, took nearly a decade.

Velcro® consists of 2 parts: the lineal fabric strip with the tiny flexible hooks, and another fabric strip with tiny loops. When pressed together, the two adhere to one another, and can be separated when pulled apart deliberately. Initially Velcro® was made with cotton, which wasn’t practical. Currently Velcro® is constructed from nylon and polyester.

Since it’s invention, Velcro® has been used on many products, like my shoes – instead of shoelaces, jacket cuffs and closures, and even on Neil Armstrong’s space suit, when he went to the moon in 1969.

(Contributors, 2019)

(Velcro BVBA, 2019)

Nomex® is the brand name for an inherently flame-resistant aramid fiber that is manufactured by DuPont™.  It was invented by a Scottish-born scientist by the name of Dr. Wilfred Sweeny (1926–2011).

Technically, it’s referred to as a ‘synthetic aromatic polyamide polymer’. This basically means that it’s a man-made textile whose molecules are bonded extremely tight and close together in a chain-like structure.

This chain-like structure makes the fibers immensely strong, and it’s what makes Nomex® inherently flame-resistant. This means that the fiber itself is not flammable, making the protection permanent. It’s built into the fiber itself, so it can never be worn off or washed out.

Ok, so just how does this protect the wearer?

The aramid fibers swell and become thicker, when exposed to flame. This swelling helps to create a protective barrier between the wearer and the flame. And even though Nomex® will burn if you were to hold a flame up to it; as soon as the flame is removed it stops burning.  Due to the way Nomex® is woven so thick and tightly together, makes it almost impossible for the fire to continue burning once the flame is removed from the material.

Think of it this way, the fire itself requires oxygen to continue burning. If we take away that oxygen and smother the fire with a blanket, for example, it will go out.

Sources:

(Faqs – Nomex-Industrial, 2019)

(Nomex, 2019)