Explosive Information - Safety first when cleaning up hazardous materials

In light of a recent fire at a Michigan car dealership first attributed to an exploding electric floor scrubber, a look at safely using cleaning equipment near hazardous materials is a good idea.

On July 18, a four-alarm fire spread through the Buff Whelan Chevrolet dealership in Sterling Heights. While no one was injured, thankfully, the business certainly was. In original reports, an electric floor scrubber was thought to have started the blaze, which then grew due to chemicals present in the building.

A member of the cleaning crew told a 911 operator he was scrubbing the floor when gas from a leaking fuel tank ignited the machine. However, video showed the machine operator knocking over a gas tank and continuing to clean with the machine, prompting the ensuing blaze.

Floor equipment can be used safely in commercial areas with the proper machine and training.

There are certain classifications for industrial and commercial locations that have a bearing on safety standards for said business. In the NEC, National Electrical Code, the word “hazardous” denotes the way a particular location is classified due to flammability properties within the area and specific use of the area.

Hazardous location requirements exist to prevent a fire or explosion, as well as to contain the fire or explosion should it occur. The NEC arranges flammability properties into Class I, II, and III.

You don’t classify a building as Class I, II, or III. You classify an area. In any given occupancy, you might have Class I, Class II, and Class III locations all present.

A Class I Hazardous Location is one in which flammable gases or vapors may be present in the air in sufficient quantities to be explosive or ignitable. Typical Class I locations include petroleum refineries, and gasoline storage and dispensing areas; dry cleaning plants where vapors from cleaning fluids can be present; spray finishing areas; aircraft hangars and fuel servicing areas; and utility gas plants, and operations involving storage and handling of liquefied petroleum gas or natural gas.

Class II applies to dust. The temperature marking must be less than the ignition temperature of the specific dust to be encountered.

Class III locations are those that are hazardous because of the presence of easily ignitable fibers or flyings, but in which the fibers or flyings are not likely to be in suspension in the air in quantities sufficient to produce ignitable mixtures. Easily ignitable fibers or flyings present a fire but not an explosion hazard. An example of this type of material is the cotton lint that accumulates in the lint trap of clothes dryers.

Class I, II, and III locations are further broken down into Divisions. The simplified version is a given Class will be either Division 1, in which the ignitables are significantly present under normal conditions, or Division 2, wherein the ignitables are significantly present under abnormal conditions.

In addition to the class and division, you must determine the group.

For Class I, Group A is acetylene. Groups B through D are materials with different ranges of combustibility. Group B includes hydrogen and other materials with similar characteristics. If you follow certain specific restrictions in the Code, some of these Group B locations, other than hydrogen, can actually be satisfied with Group C and Group D equipment.

Group C and Group D are by far the most common. They comprise the greatest percentage of all Class I hazardous locations. Found in Group D are many of the most common flammable substances such as butane, gasoline, natural gas and propane.

For Class II, it’s Group E, F, or G, depending upon the material.

Knowing the Class distinction of the area will aid in knowing what maintenance systems to provide.

Chemical spills need proper or specific equipment for proper cleanup.

For a fire or explosion to occur, three things are needed: oxygen, heat, and fuel. A simple spark in a confined area, be it in a room or inside a floor machine can create explosions if fuel and oxygen are present. So not sucking up flammable materials is a given.

Spontaneous combustion involves a process in which heat is produced more slowly. If the energy produced does not dissipate, the temperature will increase, causing the original process to speed up, or another reaction may take over as the temperature increases to the burning point.

Some types of dust can cause explosions under certain conditions. A spark where explosive dust particles are dispersed in sufficient quantity and concentration can led to rapid combustion. The Dust Explosion Pentagon includes five factors: oxygen, heat, fuel, dispersion and confinement. Properly monitoring these factors with the use of a vacuum. Initial explosions can dislodge more dust and lead to bigger explosion.

Having the correct vacuum and handling of it is also imperative.

In metalworking facilities it is not uncommon to see general purpose vacuums, like the shop-type wet/dry vacuums found on the shelves at hardware stores, however, they just don’t cut it in the manufacturing arena.

Continuous duty vacuum cleaners are designed to withstand 24/7 operation and to handle some of the toughest materials including heavy steel shot or mounds of fine powders.

Industrial Wet/Dry Vacuums are intended more for one way vacuuming of metalworking liquids and debris, wet and dry, and out-perform vacuums found at home improvement stores and janitorial catalogs.

In 2015, in the United Kingdom, a Staffordshire research and development company found out first-hand just how dangerous industrial vacuums can be when the right chemicals are given time to mix. Employees used a wet-vac to clean up some aluminum powder on the shop floor. The machine wasn’t cleaned out and stood all weekend in a corner, giving ample time for the aluminum powder to react with water inside the machine and create hydrogen gas. And since hydrogen is highly flammable when exposed to a spark, Monday morning came with a surprise when the machine was turned on and exploded. Significant burns occurred to the employee’s face and torso, followed by a hospital stay and missed work. The company, meanwhile, was fined almost $10,000 and ordered to pay a similar amount in damages for failing to properly assess the risks of working with dangerous substances and vacuum tools.

And it’s not just metalworking facilities that must be on guard. According to the OSHA, “A combustible dust explosion hazard may exist in a variety of industries, including: food (e.g., candy, starch, flour, feed), plastics, wood, rubber, furniture, textiles, pesticides, pharmaceuticals, dyes, coal, metals (e.g., aluminum, chromium, iron, magnesium, and zinc), 3D welding (a form of 3D printing), and fossil fuel power generation. The vast majority of natural and synthetic organic materials, as well as some metals, can form combustible dust.”

In other words, if anything in your facility makes dust, you’ve got an explosion risk. Even worse, you’ll often get a secondary explosion when accumulated dust is tossed into the air and then ignited by the blast wave.

Solutions exist.

Mind the warning labels on your equipment and chemicals in the area.

Explosion-proof vacuums are available as well as explosion-proof brushes that have an aluminum block and brass wire throughout the fill for conductivity. Use of pad holders or non-approved brushes will void the explosion-proof capabilities of the machine.

Identify where dust can hide (beams,ducts,pipes, ledges, hoods), and inspect those areas regularly. Where chemicals are stored, make sure they are stored properly and not at risk of spilling over.

Make sure proper disposal practices are followed. Clean those areas regularly and keep and maintain those records of inspection.

Providing proper employee training on operation of cleaning equipment, maintenance of that equipment and emergency response is extremely important.

To summarize, all floor equipment is not made to clean up every type of spill or mess. Use the correct machine and use it properly to reduce the probability of explosive problems.

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