Falls from heights are responsible for many deaths and injuries at work sites across Canada. In 2011, about 41 per cent of deaths and 60 per cent of critical injuries involved falls from heights at construction workplaces, according to Ontario Ministry of Labour statistics.

Workers are at even greater risk of slipping and falling right now due to snow, ice and frost.

These hazards are mainly at construction sites, rooftops, industrial yards, outdoor shipping areas, building grounds and other exterior locations.

“Workers need to maintain what I call situational awareness,” says Jim LaFontaine, health and safety manager for Dufferin Construction. “This means knowing your surroundings and being diligent about your ‘housekeeping’ by keeping walkways and other areas clear of materials and debris,” LaFontaine says.

In February and March, ministry inspectors are blitzing construction and industrial workplaces. They are checking for any hazards that could cause workers to slip, trip or fall, both outdoors and indoors.

“Slips, trips and falls are major hazards for workers in the construction and industrial sectors,” says George Gritziotis, Ontario’s Chief Prevention Officer.

“Especially in construction, falls remain the number one cause of critical injuries and fatalities,” Gritziotis says. “We’re working to improve health and safety and to prevent injuries and deaths of workers in Ontario.”

LaFontaine says construction and other sites need to be kept clear because a heavy snowfall overnight can bury debris and create tripping hazards.

“You just have to be so sure where you put your foot down,” says LaFontaine, who is management co-chair of Ontario’s Labour-Management Health and Safety Committee.

As well, friction is greatly reduced if workers walk on construction materials like steel and plywood or climb ladders that are covered in frost, snow or ice, he says. The tread on workers' footwear needs to be in good condition and anti-slip coverings may need to be worn.

LaFointaine says workers also need to be alert to possible falling snow and ice from steel and other materials overhead.

“De-icing is critical on scaffolding and bridges,” LaFointaine says. “Falling ice can be very dangerous.”

Workers can fall from heights as well as on the same level such as on floors, the ground and other surfaces.

“When we look at the history of injuries from falls in Ontario, it’s very rarely the most complicated things that cause an injury,” says Gordon Leffley, an industrial field consultant for Workplace Safety and Prevention Services.

“It’s actually the simple things that cause injuries,” he says. “Sometimes we need a little reminder of the simple things we need to pay attention to in order to prevent those injuries.”

The condition and operation of tower cranes, mobile cranes and concrete pumping equipment continues to be a key concern in Ontario. The province’s Ministry of Labour has reported that a number of incidents involving cranes and concrete pumping equipment have resulted in death and serious injuries to workers in the past few years. Some of these incidents occurred when cranes overturned, contacted electrical conductors or when the cranes or the material being lifted struck or crushed workers when the load was dropped.

Between July 1 and Aug. 31, 2012, ministry inspectors conducted a blitz of hazards involving tower cranes, mobile cranes and concrete pumping equipment. And while the inspections were limited to Ontario, the takeaways are relevant to anywhere across the country.

Inspection blitzes are part of the province's Safe At Work Ontario compliance strategy. They are announced to the sector by the ministry in advance although individual workplaces are not notified in advance. The blitzes raise awareness of known workplace hazards and promote compliance with the OHSA and its regulations.

During the blitz, inspectors focused on the following key priorities:

• Safe access and fall prevention: Inspectors checked for the required presence and adequacy of access ladders and guardrails or other access equipment. They also checked for required fall arrest equipment to protect workers who could fall from tower cranes.

• Proximity to overhead energized power lines: Inspectors checked if the crane operator maintained the minimum distance of approach from overhead energized power lines, if the voltage of such power lines was identified and if a procedure was in place to maintain the minimum distance of the crane or its load from the overhead power lines.

• Tower crane maintenance and other records: Inspectors checked for records at the construction site on the condition of tower cranes, before and after erection, including a professional engineer's design drawings for tower crane installation. Inspectors checked that tower cranes were properly inspected prior to first use, and regularly inspected and maintained afterwards. Inspectors also reviewed logbook entries to ensure operational functions (such as limit and overload limit switches) were properly tested.

• Mobile crane maintenance and other records: Inspectors checked for records such as the crane operator log book and operator manual. Inspectors checked that cranes were inspected and maintained as required.
• Training: Inspectors checked that mobile crane operators were certified to operate a crane at a construction site or were being instructed in crane operation and accompanied by a person who had the required certification.

• Various other issues: Inspectors checked on the structural, mechanical and foundational integrity of cranes, safety systems, setup, proximity to people and safe hoisting practices.

The inspectors visited many types of workplaces, including sewer and water main construction and repair; commercial building construction; asphalt paving and roadwork on existing streets; hydro utility installation, underground and above ground; underground tunnel construction; cable installation involving various types of telephone, electrical and fibre optics; and hydroelectric and nuclear power plants construction activity.

Inspectors issued orders at a rate of 2.53 per workplace visit. During this blitz, inspectors visited 527 construction projects and issued 1,481 orders, including 149 stop work orders. The total number of visits was 608 because some of the workplaces were visited several times. Orders were issued for various violations of the OHSA and the Regulations for Construction Projects.

In general, the blitz results indicate hazards involving failure to use personal protective equipment continue to be a at concern on construction projects. Maintenance of vehicles, tools and equipment also represents a major health and safety concern. Crane-related issues (such as use of outriggers, rigging methods and equipment records) represent areas where continued vigilance is also required. There is a need for a better understanding of the regulatory requirements for constructors and employers on construction projects, such as ensuring that the necessary controls for occupational health and safety are developed and implemented at construction projects.

Employers should focus on raising workplace parties' awareness of key health and safety hazards involving traffic on construction sites and during roadwork projects and thereby promoting improved health and safety for workers on construction sites with traffic and road work projects.

A health and safety culture requires all workplace parties to be vigilant and to give appropriate attention to workplace health and safety. In other words, the workplace must have a well- functioning internal responsibility system in which all workplace parties take responsibility for their own health and safety and that of their co-workers. A strong commitment by everyone in the workplace is needed to prevent injuries and illness and to reduce risk. Workplace parties are encouraged to work together to identify and control crane-related hazards found on construction projects.

Since 2008, ministry inspectors have conducted more than 266,000 field visits, 40 inspection blitzes and issued more than 426,000 compliance orders in Ontario workplaces.

One of the largest mini-mill steel producers and recyclers in North America is putting a “wet blanket” on slag dust from ladle and tundish dumping, improving safety and cleanliness while preventing dust migration. The Gerdau Ameristeel facility in Cambridge, Ont., uses a specially-designed atomized mist system developed specifically for dust suppression, reducing potential hazards and improving visibility around the dumping pit and in the nearby service area.

This facility has the capacity to produce 300,000 standard tons annually of low to medium carbon steel bars, primarily from feedstocks of recycled materials.

“At the end of a casting sequence, several tons of slag can be left over that must be purged,” senior engineer John Andric explained. “When ladles and tundishes are dumped, the falling slag has the potential to create large quantities of dust.” In short, he said, “We needed something that could control the dust quickly as it was generated, at ground level.”

After seeing a Dust Control Technology unit in action in another steelmaking facility, they opted to specify a DB-30 for the slag dump area, the smallest member of the DustBoss product family. Mounted on a movable carriage, the unit has a 7.5-horsepower motor that generates 9,200 CFM of airflow. The ducted fan design has an adjustable throw angle from 0º to 50° elevation and the standard unit oscillates up to 70º. When equipped with the new 359-degree oscillation option, the DB-30 can cover more than 30,000 square feet using just a standard 5/8-inch garden hose.

According to Dust Control Technology CEO Edwin Peterson, there are typically three different opportunities for fugitive slag particle emissions to emerge during steel processing. “The first is from the initial fall of material, and is usually of short duration,” he said. “The second occurs during subsequent tempering and cooling operations, when vapor from the cooling water rises and carries particulates into the air. Dust can also be released any time a particle’s terminal settling velocity (from gravity) is lower than the thermal updraft velocity (from heat), which causes it to rise and potentially migrate.”

Unfortunately, slag dust is made up of a number of different-sized particles, some of which are extremely small and lightweight, therefore mobile. DustBoss equipment has been extensively tested at a number of slag processing sites, with various modifications and configurations evaluated in a range of combinations to gauge their effectiveness. One of the keys to the equipment’s success has been the ability to automate operation, allowing slag processors to control on/off cycles, direction, oscillation arc and other features from a remote location or via hand-held wireless control. Fully integrated systems can be operated entirely by remote control whenever a slag dump is underway.

At Gerdau Cambridge, the DB-30 is mounted in an elevated location above the dump area and direct wired to 575 volt, 3-phase service. The company uses the city water supply, delivered through a heat traced and insulated line, so pressure remains at a fairly constant 40-60 PSI (2.76-4.14 BAR).

Andric says he’s pleased with the results from the DustBoss: “It does just what it was designed to do, delivering the mist over a wide coverage area.”

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This is an edited article provided by Dust Control Technology. For more information, visit www.dustboss.com.

Maintenance workers can often be responsible for the upkeep of several facilities in multiple locations as well as needing to drive off site to pick up tools and supplies. Because of this, it is important they prepare for the hazards of winter driving.

Conditions like snow-covered roads and black ice often make winter driving unpredictable. To help prepare and keep motorists safe on winter roads, Cooper Tire & Rubber Company encourages drivers to not only install winter tires before the first storm hits, but also use the changing seasons as a reminder to engage in routine tire maintenance. Preparing early for winter weather and anticipating and avoiding dangerous circumstances can help drivers maintain control and stay safe on the road.

"Drivers should consider replacing their all-season tires with a product made specifically for winter road conditions," said Chuck Yurkovich, vice president of global technology for Cooper Tire. "The key is to have those discussions with a trusted dealer before the first storm hits, as winter tires help maintain control and stability in icy conditions. It's also important to conduct routine tire maintenance checks as changing temperatures can affect tire condition."

In addition to properly equipping vehicles with winter tires, Cooper Tire advises drivers to follow basic winter driving and tire maintenance tips:

Drive cautiously: Experts say the best advice for driving in harsh winter weather is to not drive at all, but with more than 900,000 kilometers of road throughout Canada, driving is the most common mode of transportation for Canadians, according to Transport Canada.

• Double the anticipated stopping distance when braking anytime conditions are not dry. It will take longer to come to a stop in snowy or icy conditions.
• Do not assume a four-wheel drive vehicle will stop faster than a two-wheel drive vehicle – four-wheel drive offers no braking advantage.
• Always reduce speed during winter conditions.
• When purchasing winter tires, replace all four tires. Due to the different grip capabilities of summer, all season and winter tires, the driver will not get all of the handling and traction benefits if all tires are not replaced.
• Drivers should keep in mind that it is best to check their owner's manual to see how their vehicle should be serviced in cold weather.

Examine tread: The only part of a vehicle to touch the road is the tires, and tire tread is a vital part of handling, cornering, accelerating and braking.

• Drivers can check tread using a tread depth gauge. Insert the tip of the depth gauge into the tread lines and read the measurement. If the tread depth is less than four millimeters at any location on the tread, drivers should replace the tires. As a tire wears, snow traction is reduced. Tires that are worn close to the tread-wear indicators or that have reached four millimeters at any location on the tread, have reduced traction and should not be used on snow-covered roads or in severe snow conditions. More tread is better in winter and wet conditions.
• While examining the tread, also look for signs of uneven wear or damage such as cuts, cracks, splits, punctures and bulges. These conditions shorten the life of tires and, if not corrected, further tire damage, tire failure or air loss may occur.

Test air pressure: Tire pressure plays a critical role in the overall performance of tires. According to the Canada Safety Council, under inflation is the leading cause of tire failure and nearly a quarter of vehicles on the road have at least one tire under-inflated by more than 20 percent.

• Tire pressure decreases by about one pound per square inch for every 10-degree drop in outside air temperature, so it is vital that drivers check the air pressure regularly as winter weather approaches.
• Drivers should follow the guidelines found in the vehicle owner's manual or tire placard (or sticker) attached to the vehicle door edge to determine the correct air pressure for their vehicle's tires. A common myth is that the tire pressure listed on the sidewall is the optimal pressure, while in reality it is the maximum pressure.
• Air pressure should be checked when the tires are cool, meaning they are not hot from driving even a mile.
• Should any of these checks reveal the need for required maintenance – or when in doubt about the condition of their tires – drivers should take their vehicles to a tire dealer for a professional inspection.

For more information on proper tire maintenance, visit www.coopertire.ca.

The supervisor-worker relationship is the most important link in the organizational structure to ensure safety is being addressed in the workplace. A weak relationship at this level can make safety issues more difficult to be resolved due to workers having inadequate direction or expectations.

Problems or issues that are not properly addressed can lead to disgruntled employees. This could result in workers initiating work refusals.

Understanding the internal responsibility system (IRS) is one thing; however, applying this system in your day-to-day work activities presents many challenges.

IRS is a system, based on values and principles, which enables everyone in an organization to be directly responsible for health and safety, regardless of their position within their company. Simply put, it is the “people” component of your health & safety managed system. The IRS can be used to assist the supervisor-worker interface when it comes to identifying and resolving safety issues.

The following four step process can be utilized by the supervisor and workers as a method of addressing safety issues.


STEP 1: PREVENTION
Good line organization interactions are the building blocks for the prevention of accidents. The manager must have safety programs in place to assist the line organization in achieving their safety goals. Authority must be given to supervisors in order for them to exercise their legal and corporate duties. The manager must communicate safety expectations to the supervisor on a regular basis.

The supervisor, in turn, must ensure that the safety expectations are clearly understood by the workers and that achieving them is possible through proper job safety planning. The supervisor can accomplish this by assigning the tasks to competent workers and to advise them when issues arise during work execution.

The workers should be trained in identifying safety issues through the use of hazard awareness techniques like energy analysis and job safety analysis.
Energy analysis consists of assessing the different energy sources and the inherent hazards associated with each job. Here are some examples:

• electrical energy  >>  electrocution
• mechanical energy  >>   pinch point, crushing
• thermal energy  >>  burns

Job safety analysis consists of breaking the job steps in sequence, identifying the hazards and addressing the hazards with effective controls or barriers. Here are some examples of barriers:

• isolation (lock out/tag out)
• procedures/work instructions
• personal protective equipment

Using these types of techniques will enable the workers to plan each of their jobs safely by helping them identify and control the hazards associated with the work.

The workers are then able to assess the work on a daily basis and correct any deficiencies that are within their immediate control without the need for supervisory intervention.


STEP 2: REPORTING
Reporting must occur when the workers determine they cannot address the workplace safety issue by themselves. This could include observing contraventions or conflicts in other work groups.

There are legal requirements, in Canada, to report to the employer or supervisor any contraventions of safety regulations or the existence of any hazard known by the worker.

Many employers also have corporate requirements obligating workers to report any hazards, unsafe activities and unsafe acts to their supervisor. The reporting of safety issues can be made formally through a written report but could also be done during the job planning process, at tailboard conferences or at group safety meetings.


STEP 3: PROBLEM SOLVING
Once an issue has been reported by the worker to his/her immediate supervisor, there is a need to address and correct the problem collectively.

The following method is one example of a problem solving process:

Identify the Issue
• Accumulate all of the facts and information related to the issue. Be sure to provide as much detail as possible to clearly reflect the problem.
• Include any actions taken to mitigate the hazards.
• Document the situation in writing for future reference.

Determine the Causes
• Determine the contributing factors that are creating the issue.
• Perform an analysis of these contributing factors.
• Determine the root causes.

Suggest Improvements
• Together, the workers with the supervisor develop ideas to improve the situation.
• You may want to get help from your company’s internal resources such as the site health and safety advisor, the local joint health and safety committee or the corporate safety/wellness group.
• Suggestions must be practical to effectively address the situation.

Take Action
• Develop a corrective action plan to deal with the issue’s resolution.
• Review all actions required by the line organization and the specific work group to ensure that the work has been properly planned for execution.
• Initiate the corrective action plan.
• Upon completion, perform a corrective action follow-up to determine if the plan was successful in addressing the issue.


STEP 4: INTERVENTION
The last step is really only required if the supervisor and workers are not able to deal with the problem. This is often the case when the issue is caused by factors that are not in the work group’s control such as engineering design issues.

The supervisor will require assistance from his/her line organization in order to resolve the issue. This could include the need for an engineering review, a cost analysis (budgeting) and a formal planning and scheduling process.

There are also other groups that can assist the supervisor and workers in resolving safety issues. They are:

• the company health and safety professional;
• the joint health and safety committee;
• external safety consultants; and
• safety associations.

Each of these groups can help identify and promote safe work practices as well as determine any legal requirements involved.

Intervention may require your company’s head office or corporate group for longer term, corporate, industry wide and legal issues. The bigger the issue, the more intervention will be required from the line organization.

The need for intervention can really be summed up in the definition of IRS: “Everyone in an organization is directly responsible for health and safety, regardless of their position within their company.”

It is important that the supervisor maintain an effective relationship with their workers to help promote the IRS. This will go a long way towards preventing potential problems from becoming bigger ones. It will also help create a working environment that is both respectful and engaging to the employees.

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Guy Chenard is a safety professional with Ontario Power Generation. Reprinted with permission from The Ontario Technologist.

WorkSafe Saskatchewan wants to remind young and first-time workers — and those that manage and supervise them, too — that learning to work safely is an important part of summer jobs. Most injuries occur in July and August, and more than half occur in service, department stores, construction and manufacturing industries. The most common injuries are to hands, backs, legs and eyes.

Two fatalities in just one year — related to the same piece of equipment — led to important improvements in worker protection. Arguably, these did not go far enough, but one solution may help provide an extra boost of safety.

Mining, as anyone who works within it knows only too well, can be a dangerous industry. It is not just underground and at the coal face where serious (and even fatal) accidents can occur. There is one piece of equipment in particular that has led to serious accidents: the inclined conveyor. But a solution from Renold Couplings promises to alleviate the risk, and Rio Tinto is just one company that has taken advantage of the innovation to protect its workers.

The mining industry would find it hard to function without the inclined conveyor to transport coal. However, in the event of a loss of power, their design means that they can run backwards, out of control, if in a loaded condition. For that reason, for many years, these systems have been fitted with backstop sprag clutches. These work by allowing a shaft to rotate in one direction as the sprags slip. But if the shaft tries to turn the other way — as it will do if the conveyor begins to run backwards — the sprags immediately stand up and lock.

These same safety components are also fitted to theme park rides to prevent cars from running downhill in the event of a power failure.

Although this effectively solves the problem it was designed to, another associated problem can also occur, for which it is not only no help but is also actually the direct cause.

If a blockage occurs between the lower belt and the return end shaft, the conveyor will stall. The backstop sprag clutch then comes into operation to prevent the belt from running backwards — but as a result, tension builds in the upper belt, because the slack in the lower belt can’t feed back through the drive.

The natural reaction of the operator is to remove whatever is causing the obstruction to get the conveyor back in operation as quickly as possible. But if the tension in the upper belt isn’t released first, the sudden release that occurs when the blockage is removed will cause it to pull the lower belt rapidly around the return roller with huge force. This force can be so powerful that it has been known to cause the load on the top belt to explode in all directions, and has even pulled the worker removing the blockage into the conveyor.

One answer, developed by Renold, is the tension release and torque limiting safety holdback sprag clutch, which has been designed to enable the extreme tension in the upper belt to be released in a controlled way through controlled friction slippage of the sprag clutch element of the backstop.

With the tension released in this controlled manner, maintenance work can be carried out to remove the blockage and get the conveyor up and running again, quickly and safely.

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This is an edited article provided by Renold Couplings. For more information, visit www.renold.com.

The issue of dust explosions has been a hot topic since the early 20 century. In a book published by the NFPA in 1922, titled Dust Explosions, the authors, David J. Price and Harold H. Brown, acknowledge the need for a vacuum that can withstand the rigors of an industrial environment stating that despite every precaution to capture dust at the source, small amounts of it “will get out into the atmosphere of the mill and gather on floors, walls and ledges.”

The authors of the book knew then, as it still stands today, “if there is no accumulation of dust and the plant is perfectly clean, the explosion cannot propagate and the plant will not be destroyed.”

Even without a sufficient vacuum cleaner for industrial environments at the 1922 publishing of the book, the authors still warned against using brooms and compressed air in housekeeping practices because those methods often cause dust to be suspended in the environment during cleaning and could itself ignite, or would settle back onto floors, equipment and beams, lending itself to potential secondary explosions later.

Primary dust explosions occur when combustible dust is present, forms a dust cloud (in sufficient amounts), in an enclosed environment, with an ignition source and oxygen.

Bill Stevenson, vice-president of engineering at Cv Technology and NFPA 654 committee member, says, “the explosion is caused by the rapid pressure rise as a result of the rapid burning of the dust cloud. So it has to be in an enclosure. If it were outside you’d just have a big flash.”

Cv Technology is a Florida based corporation dedicated to the prevention, protection, and mitigation of industrial dust explosions and related fires

Stevenson further explains that if there was a layer of combustible dust sitting on a desk, “you could get it to burn by putting a flame to it, but it wouldn’t explode. If you took the torch away it would smolder and most would self extinguish; but, if you take the same dust, throw it in the air and then light it on fire, it would literally blow up in your face,” he says.

Catastrophic secondary explosions occur when the force from the primary explosion dislodges fugitive dust, producing more dust clouds, and creating a domino type effect that can cause further explosions. So if you took that same dust smoldering on the desk and waved a piece of paper to make the particles airborne, a dust cloud could form and explode.

According to an NFPA Fact Sheet titled, U.S. Industrial and Manufacturing Property Structure Fires, “U.S. fire departments responded to an estimated average of 10,500 structure fires in industrial and manufacturing properties per year in 2003-2006,” averaging 29 fires per day in the industrial sector. Of those fires, 29 percent involved shop tools or industrial equipment, and the manufacturing area was the leading origin of the fires.

Controlling the Explosion Pentagon
The explosion pentagon includes the three elements of the fire triangle, fuel (combustible dust), ignition source (heat) and an oxidizer (air), but needs two additional elements, dispersion of dust particles (in sufficient quantity and concentration), and the confinement of the dust cloud (vessel, area or building),.
 
If one of the elements is missing, a fire, or explosion can not occur. While it is difficult to remove air and fuel from the triangle, the first rule of fire prevention, and therefore explosion prevention, is to eliminate the ignition source. While most machinery manufacturers design equipment with safety in mind, mechanical equipment is capable of malfunctioning, heating up, and causing ignitions.

Although every precaution is taken to eliminate ignition sources to prevent fires, and dust collection equipment designed to safely contain most of the dust in the plant, manufacturers must make housekeeping for fugitive dust, that can be formed into a dust cloud, equally important to prevent dust explosions.

Industrial vacuum cleaners to control fugitive combustible dust should be suitable for use in Class II Div 2 areas. “Vacuum cleaners in particular are vulnerable to ignition and that is why there are only a few companies that know how to do that properly and VAC-U-MAX is one of them that does it right,” says Stevenson. “They take extraordinary care to make sure there is no chance for the product to come into contact with anything ignitable.”

Vac-u-Max, the pioneer in industrial vacuum cleaning and pneumatic conveying since 1954, makes a line of combustible dust vacuums that are redundantly grounded and ideal for combustible dust.

Any time there is powder flowing in one direction through a plastic vacuum-cleaning hose it can create a significant static electric charge. In addition, there is the possibility that there may be static electricity build-up on individual dust particles. If a charged, ungrounded hose used to vacuum combustible dust powder were to contact an object that was grounded, the static electricity could then arc and trigger a violent explosion. This is why OSHA has issued numerous citations for using standard vacuum cleaners where Class II Div 2 equipment is required.

The Right Tool for Combustible Dust
Bill Bobbitt of Bobit Associates Environmental Systems, who’s been working in the clean air industry for over 25 years, says, “I always tell my clients, it not a matter of if, but when. Conditions have to be perfect and that ‘when’ can be 30 years from now, or it could be next week. But if you eliminate the fugitive dust, it cannot create a secondary dust explosion,” he says.

Bobbitt sees a lot of standard shop type vacuums in plants. "There are so many problems with them. They themselves are hazards in an industrial environment," he says. First and foremost, they are not grounded or classified for Class II Div 2 areas, they shock workers, they clog easily and the workers don’t want to use them, and if workers don’t use them, fugitive dust is accumulating in the plant.

Employing an industrial vacuum cleaner that is redundantly grounded in five different ways, “eliminates the possibility of any kind of explosion from the vacuum,” says Bobbitt. Although Vac-u-Max does make electric vacuums designed for Class II Div 2 environments, the most economical solution for cleaning combustible fugitive dust is its air-operated vacuums.

Beyond the fact that air operated vacuums use no electricity and have no moving parts, the first of the five ways that VAC-U-MAX vacuums are grounded begins with the air line that supplies the compressed air to the units. Because most plants have compressed air lines made from iron that conducts electricity, the company’s air operated vacuums use static conductive high pressure compressed air lines. In addition to the static conductive air lines, static conductive hoses, filters and casters are employed to further reduce risk. A grounding lug and strap that travels from the vacuum head down to the 55-gallon drum, eliminates the potential for arcing.

Air operated vacuums for combustible dust are safer in terms of grounding, they also work more efficiently in the industrial environment. Bobbitt says on a recent visit to a coal fired electric power plant he was shown five different electric vacuums sitting in a warehouse not being used because after 20 minutes, the filters would bind and workers just didn’t want to use them because they would have to lift the head from the vacuum and tap the cake off before they would get any more suction.

The power plant and now two sister facilities, Bobbitt says, “now use an air powered VAC-U-MAX model with a pulse cleaning system on the filters, that with the push of a button releases the dust from the filter and they can resume cleaning.”

Compliance when Regulations aren’t Clear
Fugitive dust “is a moving target that changes depending on the nature of the process and how well plants manage keeping the dust contained,” says Stevenson. Most NFPA guidelines for combustible dust state that a layer of dust the thickness of a paperclip is enough dust to cause a significant secondary explosion. The problem he says, “is that it doesn’t account for the different Kst values between different dusts. Some are more reactive than others. Some are more easily suspended into a cloud. Some tests found that depending on the type of dust, even half of the thickness of a paper clip would be too much.”

Kst values classify dusts according to their explosivity—the rate of pressure rise of a dust in the test vessel upon being ignited.

In situations where many different dusts are handled, testing all of them can be prohibitively expensive. For instance, in a high performance rubber plant where several different products are manufactured within the same plant, the dust in each area of the plant may have different Kst values in each area. For this circumstance it is recommended to work with an expert in the field to select samples for test that represent the worst case.
 
This is why, Bobbitt says, that when you are dealing with explosive dust, you may need a Class II Div 2 vacuum in a non Class II Div 2 area. “You might have explosive dust small quantities, and it might take a very hot and prolonged source of ignition, but with the new combustible dust initiative, facilities need to be very careful that they comply because there is a lot of question as to what compliance means.”

“Although the regulations for combustible dust aren’t real clear,” Bobbitt says, “I find that a lot of companies are simply just trying to get better at general housecleaning.”

Cv Technology’s Stevenson agrees. “The one thing you can do very simply and easily is to keep everything clean—it is as simple as that. If you clean the place up and protect your dust collectors, you’ve gone a long way toward minimizing the chance for an explosion even if you do nothing else and those are pretty straight forward easy things that everyone can do,” he says.
www.vac-u-max.com