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32D July 2019 Tablets & Capsules 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 ter- minal 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 of the flowrate measure- ment using the following equation: input − output × 100 input The recommended acceptance criteria is ±5 percent. 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 in 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. Calcu- late the percent error using 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 col- lector is not operating as efficiently as it could be, pre- ventative maintenance needs to be performed by a qualified technician. T&C References 1. Chris Fluharty, David Steil and Kevin Tucker. Dust collection tips for food processing" Processing Magazine, 2018. www.processingmagazine.com/dust-collection-tips- for-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. www.dwyer-inst.com/ApplicationGuides/?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 environ- mental 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. Respiratory Protection. Dietary supplement manufac- turing often requires machine operators to handle ingredi- ents with potentially hazardous physical or chemical prop- erties. As previously stated, OSHA regulations require dietary supplement manufacturers to install approved engi- neering control measures that provide dust collection pro- tection. 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 pro- cess. 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 measurements [4]. 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. Fig- ure 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- Figure 2 Traverse reading points for a rounded duct Traverse points or centers of the equal concentric areas Equal concentric areas