Exposure Assessment: Muriatic Acid
|Please Note: This page is (1) under development, (2) is in rough-draft form and (3) has not been peer-reviewed.|
KCPE staff requested an exposure assessment during chemical transfer of muriatic acid (syn. hydrochloric acid, 32%) from carboys to the main storage tank.
KCPE staff indicated the carobys from the new supplier lack a vent. This causes excessive exposure to irritating HCl vapor by two methods: (1) more steps are required to transfer liquid thus resulting in greater exposure time; and (2) the lack of a vent results in more splashing and "glugging" as the liquid is poured resulting in more liquid agitation and vapor generation.
According to the KCPE staff, the containers used by the previous supplier allowed air to enter the carboy as the liquid was poured thus resulting in less exposure to the irritating vapors.
Please Note: These scenes were posed for demonstration purposes only. Recommended personal protective equipment (PPE) which is normally worn was not utilized for this demonstration.
Another view of the funnel transfer system. Pool chemicals are poured into the funnels, which are connected to the main storage tanks located in the sub-basement level filter room. Currently, there is no local exhaust ventilation, only general-room dilution ventilation.
Occupational Exposure Limits and Hygienic Values (1999): Muriatic Acid (syn. Hydrochloric Acid):
OSHA PEL (Ceiling*): 5 ppm
NIOSH REL (Ceiling): 5 ppm
IDLH: 50 ppm
ACGIH TLV "Ceiling": 5 ppm
Odor Threshold: for practical purposes, about the same magnitude as the PEL/TLV
IARC Group III (not classified as carcinogenic in humans)
*Note: The "ceiling" exposure is generally defined as the concentration that should not be exceeded during any part of the working exposure.
Observations / Recommendations:
Personal exposure monitoring was not performed during this demonstration. However, area-monitoring using colorimetric indicating tubes revealed high concentrations of HCl (approximately 20+ ppm for daily routine, using Dr�ger 1/a short-term tubes). Exposure reduction methods become mandatory given the levels encountered during the demonstration. The following is a list of possible exposure reduction techniques and recommended practices:
- Until chemical exposure is reduced or, preferably, eliminated, all staff involved in this process shall wear approved respiratory protection. All staff wearing respiratory protection shall be involved in all facets of the UWM Respiratory Protection Program.
- Obtain chemicals in vented carboys from the new chemical supplier, or obtain chemicals from the previous vendor.
- Punch hole in new-style carboys to create vent hole in order to eliminate "glugging" when liquid is poured.
- Use a pump activated chemical transfer method, thereby minimizing chemical exposure, potential for chemical spills, and potential ergonomic hazards.
- Introduce chemicals to the storage tank from a tanker truck (pool chemical service) rather than from carboys.
- Currently, this equipment room only uses general dilution ventilation. The preferred method to reduce or eliminate unnecessary chemical exposure is to install a local exhaust ventilation system (i.e., vapor exhaust system) where chemicals are handled. Chemicals would thereby be removed at the source rather than being removed by dilution.
- This is high likelihood of chemical spills during the transfer process. According to the MSDS for muriatic acid, the recommended personal protective equipment includes:
Chemical goggles or face shield and chemical goggles.
- Chemical resistant gloves (see CCOHS ChemInfo sheet for details).
- Coveralls, boots, or apron to avoid skin contact.
- Respiratory protection based on airborne levels of contaminants.
- Implement a spill control plan (i.e., emergency action plan) in the case of chemical spill or chemical exposure.
- Note: Check code compliance for location of nearest emergency shower/eyewash station in regard to work area.
- There are several ergonomic concerns with the current setup. For example, there is a great deal of manual handling of heavy carboys and pails, and lots of bending and stooping. Would it help if the funnels were reduced several inches so that the carboys/pails wouldn't have to lifted to chest height? Again, a pump transfer system would greatly reduce the frequency of manual lifting activities.
This process is still under investigation. Physical Plant Services will perform additional air monitoring to ensure the effectiveness of any control methods which are implemented by KCPE.