Many companies decide to perform their combustible dust cleaning themselves, either for scheduling or budgetary reasons. The initial cost of having an employee just take a shop vac and try to clean it themselves may be lower than paying a professional like Hughes Environmental, but the risk just isn’t worth it. If an explosion occurs, and chances are it will, then the damage could be in the millions of dollars. We’ve seen companies who had to close their doors for good because a lawsuit from a dust explosion cost them so much.
So why is doing it yourself with a shop vac such an explosion hazard? Here are 6 reasons NOT to use a shop vac to clean combustible dust:
The National Fire Protection Association codebook 654 “Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids 20013 Edition” outlines the proper way to clean dust. In section 8.2.3 it clearly specifies the requirements a vacuum must pass in order to be used for combustible dust cleaning.
Among the requirements that a shop vac fails: hoses shall be conductive or static dissipative, conductive components shall be grounded, dust laden air shall not pass through the fan or blower, and electrical motors shall not be in the dust laden air stream.
Ungrounded Plastic Hoses and Body
Shop Vacs are primarily made out of plastic, but when the dust particles travel through the plastic tube and then spin around the body they create large amounts of static electricity. Since these vacuums are not grounded this static electricity can be randomly dispersed and cause an explosion either inside the vacuum body or the dust laden air outside it.
The explosion proof vacuums Hughes Environmental uses are properly bonded and grounded to prevent any static discharges.
Brushed DC Motor Can Spark
Another sparking hazard that shop vacs create is within the motor running the vacuum. These are typically a brushed DC motor, and when these motors start to wear down the contacts can spark every time it is turned on. These sparks are contained within the motor housing, so they typically don’t pose a danger to people nearby. When placed in the middle of a dust cloud this sparking motor can create the ideal ignition source for a combustible dust explosion.
The explosion proof vacuums that Hughes Environmental uses are designed to prevent motor sparking, either by using compressed air or a specially designed motor.
Exhaust Creates Dust Cloud
Shop vacuums work by spinning the collected dust in a small tornado within the body, and the heavy dust eventually falls to the bottom where it is collected. The air that is sucked into the vacuum is then forcefully blown out the exhaust port. The air blown out from the use of the vacuum can be strong enough to disturb dust that has settled on surfaces, causing it to become airborne and create a dust cloud.
Now, while trying to remove hazardous dust conditions the employee has actually made them significantly worse. Many dust explosions can be traced back to a single event that caused settled dust to disperse into a cloud, where it then contacted an ignition source and combusted.
Unable To Filter Small Particles
The typical shop vac is not designed to deal with the fine particles that typically make up combustible dust hazards. First, these vacuums are not powerful enough to efficiently collect all the loose dust, and will leave behind enough dust to still create a hazard. The explosion proof vacuums that Hughes Environmental uses are 5 times as powerful as the standard shop vac.
Secondly, shop vacs don’t use high quality filters that can filter out the small combustible dust particles. They are great and vacuuming up larger dust, but small particles can still be blown past the filter and back out into the air.
Have To Be Cleaned Regularly
Shop vacs fill up and get clogged quickly, particularly in dust heavy locations. Once they start to fill with dust they stop providing as much suction, and can overheat quickly. If an employee is trying to use a standard vacuum to clean large amounts of combustible dust they will have to stop to empty the vacuum and clean the filter constantly.
Many employees will get tired and frustrated by this, and will eventually stop cleaning thoroughly. This can cause the task of cleaning to be longer and less efficient than if a trained professional is able to perform it with the 55 gallon capacity vacuum that Hughes Environmental uses. These vacuums are designed to not clog or lose suction as they fill up, and work doesn’t need to stop constantly to clean it.