Dunn-KH; Echt-A; Garcia-A
NIOSH 2008 Jan; :1-34
Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted an evaluation of a local exhaust ventilation system installed in the liquid compounding room at Gold Coast Ingredients, Inc. The ventilation control system was developed and installed by Gold Coast in conjunction with a contractor to reduce the potential for employee exposure to harmful flavoring chemicals. The ventilation system for the compounding room was developed following an initial visit by NIOSH in November 2006. Following that survey, recommendations on the design and implementation of engineering controls were provided to the company in a letter dated February 7, 2007. This survey was conducted to evaluate the installation of new ventilation controls for the weighing and pouring of chemicals on the bench top and the mixing of large scale batches of flavorings in mixing tanks. Evaluations were based on a variety of tests including tracer gas experiments, air velocity measurements, and smoke release observations. The experiments showed that generally there is good capture by the all LEV hoods under the tested conditions. Tracer gas tests were performed under a variety of conditions including the movement of the emission source to areas across the bench top surface to evaluate the spatial capture efficiency. Also, experiments were conducted using a mannequin to evaluate the effect of the disturbance of the body on the performance of the hoods. Capture efficiencies were calculated based on measurements of the concentration of tracer gas in the exhaust duct under test conditions versus the concentration when tracer gas was released directly into the duct (100% capture condition). The measured capture efficiencies exceeded 95% for all hoods installed. Air visualization tests and velocity measurements indicated good capture characteristics and were consistent with the results of tracer gas testing. Despite the test results indicating excellent hood performance, air samples collected during the survey indicated that flavored powder packaging done in one of the ventilated booths yielded high worker exposures and a corresponding increase in concentrations of diacetyl in the general flavoring production area. This is likely to be due to issues associated with the operation/location of the proximity switches in those booths. Based on the results in this report, the following recommendations are made to further improve the local exhaust ventilation in the liquid compounding room: 1) Evaluate the design and operation of the proximity switches in the booth-type hoods for all processes including powder packaging and any other auxiliary procedures; check all operations being conducted in these booths to evaluate whether the worker is being adequately protected during all tasks. 2) Install hood static pressure gauges on each hood to provide important information on hood performance; include the recording of hood static pressure and performance of hood airflow checks into the preventative maintenance schedule. 3) Extend the bench-top hood side baffles to the edge of the bench; the extension of the side baffles on the bench-top hoods will further enclose the operation and improve performance by minimizing the effect of cross drafts on hood capture. 4) Discontinue the use of floor fans and wall-mounted fans as they interrupt the capture of the hood and reduce hood performance by creating drafts within the room; consider using ceiling-mounted supply registers to provide lower velocity and more uniform cooling/air movement in the compounding room. 5) Consider upgrading hood and duct materials to higher gauge galvanized steel when appropriate; upgrading to a higher gauge (thicker) galvanized sheet metal will improve the system's ability to withstand the wear and tear of ordinary use. 6) Consider installing an indication of exhaust fan operating status (on/off) such as a light for each hood so that workers know when the system is operating and they are being protected when working with the hoods. 7) Provide worker training on proper techniques for using hoods such as clearing the bench of unnecessary chemicals/materials and, as much as possible, to reduce the obstruction of airflow into the slot exhaust. 8) Consider using the booth for packaging of liquid flavorings and pouring of high priority chemicals until other controls are in place for these tasks; ensure that the workers use proper techniques and that the control system allows for activation of the exhaust fan when performing these tasks. 9) Consider reworking the roof-top exhaust stack design to ensure that hood exhaust is effectively discharged.
Control-technology; Engineering-controls; Region-9; Food-additives; Food-processing-industry; Food-processing-workers; Acetals; Respiratory-system-disorders; Lung-disease; Exhaust-ventilation; Ventilation-equipment; Chemical-processing; Control-systems; Exhaust-hoods; Air-sampling; Exposure-assessment
National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Engineering and Physical Hazards Branch, Mail Stop R-5, 4676 Columbia Parkway, Cincinnati, OH 45226-1998
Field Studies; Control Technology
NTIS Accession No.
National Institute for Occupational Safety and Health