Karthik Maniam Nature’s Value
A properly-designed dust collection system is a dietary supplement manufacturer’s best defense against cross-contamination, dust accumulation on surfaces, dust explosions and fires, and harm to plant workers1. A dust collection system is also imperative for following federal regulations.
The FDA’s regulation for current good manufacturing practice (cGMP) for dietary supplements (21 CFR Part 111.365) requires dietary supplement manufacturers to implement safeguards to prevent contamination of components or dietary supplements2. Additionally, the Occupational Safety and Health Administration (OSHA) standard, 29 CFR Part 1910.134(a)(1) specifies, “In the control of those occupational diseases caused by breathing air contaminated with harmful dusts, fogs, fumes, mists, gases, smokes, sprays, or vapors, the primary objective shall be to prevent atmospheric contamination. This shall be accomplished as far as feasible by accepted engineering control measures such as installing the dust collection system.”3.
Documented verification of dust collection system efficiency is the only way to prove that a system is operating in compliance with cGMP regulations and OSHA standards. These verifications also help to diagnose problems such as heavy accumulation of solids known to clog and corrode a dust collection system’s components. This article will explain the role of dust collectors in the dietary supplement manufacturing process and describe a method for verifying the efficiency of a dust collection system.
Dust collector components and uses
The basic components of a typical dust collection system are a blower, a duct with one or more air inlets or pickup points, a dust collection chamber with cartridge filters, a pulse-jet cleaning system, and a waste container (Figure 1). In operation, the blower creates a vacuum inside the duct, which draws in contaminated air from the manufacturing process through the inlets and carries it to the dust collection chamber. In the dust collection chamber, the cartridge filters separate the dust from the airstream by allowing the air to pass through the filters while collecting the dust particles on the filter surface. At defined intervals, the pulse-jet cleaning system injects pulses of compressed air through a diaphragm valve onto the filters in the opposite direction as the dust collection airstream, which dislodges the dust accumulated on the filters. The dislodged dust collects in a hopper at the bottom of the chamber and is discharged into the waste container.
Dust collector benefits
When a dust collector is working efficiently, it can provide several benefits such as cross-contamination prevention and housekeeping, fire safety, and respiratory protection. Cross-contamination prevention and housekeeping.
When manufacturing dietary supplements or any product intended for human consumption, preventing cross-contamination should be a top concern, especially when processing both allergenic and non-allergenic products in close proximity to each other. Raw materials can vary significantly in particle size and density, and ingredients with low densities can easily become airborne, posing a serious threat of cross-contamination and causing housekeeping problems by settling on cleaned equipment, product-contact surfaces, plant floors, or any horizontal surface in the area. To minimize these risks, potential airborne contaminants must be trapped at the source with a dust collector as the first line of defense.
Fire Safety
The dust generated when manufacturing dietary supplements is often combustible, which can cause dust explosions and fires. Installing an NFPA-compliant dust collection system equipped with proper deflagration protection will minimize the threat of dust explosions and fires in the manufacturing plant.
Respiratory Protection
Dietary supplement manufacturing often requires machine operators to handle ingredients with potentially hazardous physical or chemical properties. As previously stated, OSHA regulations require dietary supplement manufacturers to install approved engineering control measures that provide dust collection protection. Since it is impossible to design product-specific respirators for all employees, an effective dust collection system can provide the required protection.
Verifying a dust collection system’s efficiency
To verify the efficiency of a dust collector, you must calculate the percent error of the equipment’s volumetric airflow rate and blower speed.
Volumetric airflow rate
Calculating the volumetric airflow rate in a dust collection system is a two-step process. First, measure the input volumetric airflow rate at the duct between the blower and the dust collector, then measure the output volumetric airflow rate at the point-of-use terminals. Volumetric flow rates can be measured using an anemometer and the principle of traverse flow measurements4. According to this principle, if the duct diameter is 4 inches or larger, the average volumetric flow rate can be determined by taking a series of readings at points of equal area, also known as traverse readings. Figure 2 shows the five recommended traverse reading points for round ducts. It is important to identify four locations in the duct where there are no elbows, transitions, take-offs, dampers, or other obstructions to avoid turbulence in the airflow. Using a calibrated anemometer as a known test standard, measure the input volumetric flow rate at the five traverse points for each of the four duct locations. Then average these 20 measurements to determine the input flow rate. Next, measure the output volumetric flow rate readings at three locations from each point-of-use terminal and average these 15 measurements. Calculate the total output volumetric flow rate by adding the averaged individual point-of-use volumetric flow rates.
Once you have the input and output volumetric airflow rates, determine the percent error for the flow-rate measurement using the following equation:
Blower speed
The blower speed is expressed in terms of revolutions per minute (rpm) that can be verified using a calibrated tachometer as the known test standard. For the best results, select five set points within the operating limits. Using the tachometer, measure the blower speed and record the speed displayed on the blower. The input value is the value obtained using the tachometer and the output value is the value displayed on the blower. Calculate the percent error using the same equation for flow rate percent error. The acceptance criteria for the blower rpm reading should be ±5 percent of each setting.
If any of these calculations suggest that the dust collector is not operating as efficiently as it could be, preventative maintenance needs to be performed by a qualified technician.
References
1. Chris Fluharty, David Steil and Kevin Tucker. Dust collection tips for food processing” Processing Magazine, 2018. www.processingmagazine.com/dust-collection-tipsfor- food-processing/.
2. www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/ CFRSearch.cfm?fr=111.365.
3. www.osha.gov/pls/oshaweb/owadisp.show_docu ment?p_id=12716&p_table=standards.
4. http://www.dwyer-inst.com/Application Guides/?ID=16.
Karthik Maniam is a quality assurance manager at Nature’s Value, Coram, NY (631 846 2500, www.naturesvalue.com, kmaniam7@gmail.com). He is a licensed professional environmental engineer in New York and Vermont and holds a master’s degree in environmental technology from New York Institute of Technology and a master’s degree in chemical engineering from Vellore Institute of Technology in India.