Jessica McKeil   |   5 days ago

Hazards of Drying Ovens and How to Prevent Catastrophe

The increase in drying ovens has also meant an increase in risk for the hemp processor.
Jessica McKeil is a freelance writer focused on the medical marijuana industry, from production methods to medicinal applications. She personally found relief through cannabis for the treatment of her panic and anxiety disorder. She is lucky…

In 2020, there were roughly 465,787 acres of hemp planted across the US. Since the Farm Bill's most recent evolution in 2018, this has led to a 455 percent increase in hemp production. Naturally, with the rise in supply, an expansion in the processing infrastructure has followed. This includes the technologies used to speed up drying times, such as the hemp drying oven.

Hemp dust is proving just as explosive as grain dust, especially with the heating element of the drying oven. Over the last year, several hemp processing facilities have burned to the ground, highlighting just how necessary fire safety and routine maintenance is within these facilities. The combination of dry, combustible material, heat, and enclosed space is a risk no one should take lightly.

2020 Saw an Increase in Hemp Drying Facility Fires

As new facilities come on board to process the rise in raw material, concern is rising with the hazards these businesses create. In 2020 alone, several fires were reported across the country at hemp processing facilities, all of which had hemp drying ovens on site.

On July 22, 2020, a fire completely destroyed a rural hemp processing facility in Lowe, Colorado. Its rural location and lack of a water source made it nearly impossible to salvage. According to reports, the local fire department was unaware of the facility, although it appears to have been licensed. Both a fire crew and a HAZMAT crew responded to the blaze, and while they were not able to prevent the facility from burning down, they did stop the fire before it reached nearby propane tanks.


(Credit: David Jones)

More recently, on November 5, 2020, Colorado Hemp Solution was destroyed by fire. The facility was relatively small and consisted of two side-by-side greenhouses joined by a hemp drying oven. As per local reports, the fire initially began within the oven and quickly spread to the rest of the structure.

A day later, on November 6, 2020, another hemp processing facility was reduced to ashes, this time in Lebanon Township, Pennsylvania. Although little information is available on the particulars of this situation, firefighters at the time believed the fire began in the drying room. HV Bioprocessing, the business behind the facility, has not released a statement.

How to Prevent Catastrophe

Although hemp cultivation is a far cry from grain farming, these recent fires at hemp processing facilities highlight key similarities in risks. Grain farmers have long known about the devastating risks posed by grain dust, and now it seems as though these same lessons need to be translated for hemp production.

A grain dust explosion requires five components: oxygen, an enclosed space, ignition source, dispersion, and fuel. In hemp facilities with an industrial-sized drying oven, presumably, all these components are available. Hemp dust from the dried plant material stands in for what would traditionally be grain dust, but the risks are the same.

As more hemp producers install drying ovens to serve an ever-expanding sector, what preventative measures can hemp processors put in place to avoid the increased risk of fire and possibly explosion?

Routine Maintenance & Cleaning

Handling hemp naturally creates fine flammable particulate matter, from the shredder to the conveyor belt to dumping it into storage. These dust particles disperse in the air and settle throughout the facility, even within the oven. Routine cleaning is necessary to prevent excess and dangerous buildup and to reduce dust. A hemp drying oven must also have a filter on the air intake, which prevents any particulate matter from entering the heater.

Ventilation

Perhaps the most crucial aspect of any hemp drying facility is the need for robust ventilation. Ventilation controls temperature but also removes the hemp dust from within the enclosed space. Ventilation has always been a concern for indoor cultivation, but it is exponentially more critical for heat-based drying facilities. Ventilation schematics must consider the expected processing, the internal and external relative humidity, and heat production.

Appropriate Fire & Safety Plan

In at least one of the fires from 2020, the fire department was not aware that the facility existed. This exasperated the fire department's efforts. During the initial setup, licensed facilities have an obligation to coordinate and consult with local fire departments. Their input is critical to reducing the potential fire risk. All facilities housing a hemp drying oven should also have a sprinkler system suited to the building's needs. As many facilities are located outside of city limits, and therefore not near municipal water sources (fire hydrants), a plan B is necessary.

Location and Setup

Remember, one of the key features of a dust explosion is the enclosed space. But hemp ovens do not need to be located within an enclosed facility. Larger models, like the dryer used by Endoca CBD, are placed outside, directly in the field. This immediately reduces dust and thereby reduces fire risk. If the oven does catch fire, the rest of the processing plant is not at risk as it's located away from the oven.

Avoid Catastrophe with Preventive Measures

The three hemp facility fires in 2020 will likely not be the last in the American hemp industry. The lessons learned in other agricultural sectors are valuable for hemp but slow in their adoption.

Most hemp drying ovens create the ideal components for devastating dust explosions more commonly seen in the grain industry. For any processors working with heat, agricultural dust, and enclosed spaces, preventative measures are incredibly necessary. From system schematics to proper ventilation to a fire and safety plan, there are ways to mitigate this risk and avoid total catastrophe.

 

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