PPE for engineers

From bakers to mechanics, occupational safety affects everyone. And plant engineers are no different. Plant engineers must wear flame-resistant (FR) clothing when working with large volumes of organic solvents and chemicals with the potential to explode. However, engineers must also make sure they are wearing the correct type of personal protective equipment (PPE) for the PPE to work as intended.

FR clothing has many different characteristics that vary depending on specific occupational needs. Consequently, there is a wide variety of different FR clothing types available for a wide range of occupations. In general, flame-resistant clothing is clothing designed to resist intermittent exposure to flame or heat.

When it comes to PPE, different performance ratings measure the clothing’s resistance to different risk types. Arc ratings refer to the fabric’s ability to protect the wearer from second-degree burns and are divided into two categories: arc thermal performance value (ATPV) and energy break-open threshold (EBT).

ATPV and EBT ratings are given in heat calories per centimetre squared. An APTV rating means that wearers have a 50% chance of receiving second-degree burns during a flash arc, while EBT ratings reflect the point at which the clothing bursts open after five trials of high heat exposure.

Whether the garment uses an EBT or ATPV rating is ultimately less important than the heat calorie level the fabric can tolerate. The greater the calorie number, the greater the protective ability of the clothing.

Most flame-resistant fabrics blend several fibres. These highly engineered materials are often a combination of synthetic fibres that only catch fire at extremely high temperatures.

Some frequently used FR fabrics include Kevlar, nomex and modacrylic. Kevlar is known for its use as a bulletproof fabric, but this Dupont-made material also is an exceptional flame-resistant fibre. With five times the strength of steel, Kevlar resists ignition in temperatures up to 800 degrees Fahrenheit. Nomex is more commonly associated with FR clothing than Kevlar as another Dupont product often used in firefighter uniforms. This durable fabric can withstand up to 700 degrees Fahrenheit and does not rip or tear in extreme conditions. Besides clothing, Nomex sheets shield heat-sensitive components for space programmrs. Modacrylic fabrics have many common uses in workwear, including cotton blends for everyday wear. These fabrics tolerate temperatures up to 425 degrees Fahrenheit but do not melt and often extinguish the flame. Consequently, Modacrylic is considered one of the safest fabrics for flame protection.

The USA’s National Fire Protective Association (NFPA) identified four flame-resistant hazardous risk categories, with 1 representing the fewest PPE requirements and 4 requiring the most PPE. These categories set performance criteria and guide minimum design requirements for FR clothing through a series of testing protocols.

The employer should provide the plant engineers with flame-resistant clothing requirements if required for their job. Depending on jurisdiction, this may or may not be a safety requirement, and engineers should consider requesting information about their employer’s safety processes if not provided.

Even with a solid understanding of the different varieties of FR clothing, it can still be hard to know what to wear and when to wear it. Plant requirements and risk exposure are two pillars undergirding appropriate PPE selections

The employer is responsible for the engineer’s occupational health and safety and often has to comply with local occupational health requirements regarding PPE. In the USA, the Occupational Safety and Health Administration (OSHA) oversees worker rights and protections.

OSHA’s guidelines dictate that plants should conduct a hazard assessment to determine which PPE needs to be worn on the job and when. This hazard assessment should dictate what type of clothing an engineer would need to wear, but if any grey area persists, the engineer may wish to review general information about PPE when choosing flame-resistant clothing.

Plant engineers need to wear PPE when working around chemicals at risk of reacting with air or water that lead to a combustible explosion. Combustion of these chemicals poses a range of risks, including:

● Flash Arcs

Flash arcs or arc flash is the flash of heat and light emitted following a reaction. Released energy heats the air to almost 35,000 degrees Fahrenheit with the potential to harm the engineer and release a pressure wave.

● Flash Fires

Like flash arcs, flash fires occur following the accidental emission of flammable fuel. The size and longevity of the flash fire are determined by multiple factors, including the amount of fuel accidentally released. Flash fires are estimated to reach temperatures as high as 2,000 degrees Fahrenheit, and injuries incurred by most plant employees usually happen within the first six seconds of the flame burst.

● Combustible Dust

Combustible dust is any fine, particulate material that can spread through the air and explode when exposed to an ignition source. These materials can be in the form of solid organic material like flour, textile fibres such as cotton, or fine metals. Some materials are not normally combustible but become dangerous when built up or released.

If an employer does not have specific requirements for FR clothing, an engineer may wish to consider how much skin coverage they need to determine what type of clothing is required. For example, depending on the task, it may be more important to wear an apron and long gloves instead of coveralls.