Control Measures of Hazardous Chemicals
Instructions
Recommendations for Controlling Hazards
As the environmental health and safety (EHS) manager, you have been asked to evaluate an existing operation to determine employee’s current exposure to hexane, which is a chemical used in painting processes.
You are to complete an evaluation of the employee’s current exposure by determining the employee’s exposure to hexane (toxic contaminant) by calculating time-weighted average (TWA) and compare it to the permissible exposure limit (PEL) and modify the PEL, if necessary. If it is necessary to modify the PEL, explain the reasoning why it is to be modified. Once the current exposure has been determined, select the appropriate ventilation system between dilution and local exhaust that is the best choice to control the concentration of the contamination. Ensure that you provide the reasons why you think your selection of ventilation system is the best choice. You are to provide the results in a three-page project report using the Unit III Consulting Report template .
Scenario
An employee working in a room measuring 15 ft x 20 ft x 15 ft sprays paint assembly parts using a paint containing hexane. The PEL for hexane is 500 ppm. The employee wears a half-face, air-purifying respirator, but management would like to install engineering control measures to reduce or eliminate the employee’s exposure to hexane. The options are to:
(1) install a dilution ventilation system, or
(2) install a local exhaust ventilation system.
The employee works a 9-hour shift and has the following exposures:
For the general dilution ventilation system to work, there must be at least 20 room air changes per hour. The fan which supplies air to this area produces 1,500 cubic feet per minute (cfm) (Q).
In order for the local exhaust ventilation system to remove the contaminant to acceptable concentrations, the capture velocity must be at least 140 feet per minute (fpm). The proposed local exhaust system ventilation system uses a 1.0 feet diameter duct and a fan that provides a total volume of 1,275 cubic feet per minute (cfm). The source of the contamination is located 1.5 feet from the opening of the duct. Determine the appropriate ventilation control and calculate the capture velocity.
Complete your project by following the Unit III Consulting Report template linked above. Ensure you show your equations and all work for determining answers for all three scenarios in the project document. You may either formulate the scenario equations using the Word equation formula toolbar or write out and solve your equations with answers on a separate paper. Then, take a screenshot of your work for each scenario using your phone or similar device and insert it as an image in the document. Make sure your image is clear and legible to read.
No references are required for this assignment; however, if outside sources are used, please adhere to APA Style when creating citations and references for this assignment.
Control Measures of Hazardous Chemicals
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Control Measures of Hazardous Chemicals
Health safety is essential for employees to perform their duties in any firm. It is a requirement by the law everywhere that employees be protected from exposure to dangerous chemicals as they carry out their operations (Pałaszewska et al., 2019). A firm operating using hexane intended to evaluate its employees' current exposure to hexane. Hexane is a chemical that is used in the painting process. Regarding the evaluation, the firm intended to determine the hexane contamination by calculating and analyzing the time-weighted average (TWA) and making a comparison with the existing permissible exposure limit
(PEL). Modifying the permissible exposure limit is necessary for determining the appropriate control measure for the hazardous chemical. The evaluation also intended to provide a preferable selection for the ventilation system between dilution and local exhaust and see which can best suit to control the concentration of the hexane. The permissible exposure limit for a 9 hours shift was calculated to be 444.4 ppm, the time-weighted average was 420.28 ppm, and velocity capture was 54.76 feet per minute.
The sampling exposure is given below,
Sample
Sampling time (minutes)
Concentration (ppm)
1
90
550
2
348
400
3
102
375
Methodology
To identify the daily average exposure of hexane to the employees, we are required to determine the time-weighted average, which is given by the following equation
TWA = (C1T1) + (C2T2) + (C3T3) / Total hours of work
Where:
C1, C2 and C3 = Concentration of hexane
T1, T2 and T3= Time
Therefore, TWA= (C1T1) + (C2T2) + (C3T3) / Total hours of work
Implying that TWA= (550 ppm × 1.5 hours) + (400 ppm × 5.8 hours) + (375 ppm × 1.7 hours)/ 9 hours of shift
This gives TWA= (825 ppm/hour) + (2320 ppm/hour) + (637.5 ppm/hour)/ 9 hours
TWA= (3782.5 ppm/ hour)/ 9 hours
= 420.28 ppm
Therefore, the time-weighted average is 420.28 ppm.
Usually, the permissible exposure limit (PEL) is calculated on an 8 hours shift, which is modified to match a 9-hour shift in this scenario. Also, it must be recalled that the permissible exposure limits (PELs) can only be modified when the working shift exceeds the established 8-hour shift, and the modification is necessary to help determine the level of permissible exposure limit of hexane.
The given equation was used to modify the permissible exposure limit, that is;
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