Diluted Chemical Shower Delivery System Design
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Date
2021-12-08
Authors
Ahmad, Faizan
dela Merced, Geron
Dyck, Riko
Singh, Jaskaran
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Abstract
Team 2 was tasked with the design of a complete chemical delivery system for six decontamination showers at the National Microbiology Lab (NML) in Winnipeg, Manitoba. The NML is involved in disease and pathogen research, lab-based surveillance, emergency response and preparedness, and other specialized services recognized nationally and globally. The showers are containment level 4 (CL4) showers, which designate the highest biosecurity requirements prescribed by the Canadian Biosafety Standard. Staff wear positive pressure hazmat suits to enter the lab, which are decontaminated with a 5% MICRO-CHEM PLUS (MCP) solution upon exit. The NML has tasked Team 2 with the redesign as the current shower setup is inefficient and unreliable, resulting in excessive water usage and frequent pump failures. The client has also indicated that redundancy is important and that a fail-safe be implemented into the system. Reliability issues are encountered due to MCP's corrosive effect on plastics and elastomers. The current system uses around 500L of diluted chemical and water per shower per cycle, with almost monthly pump failures. Team 2 generated 8 possible core concepts focusing on improving water usage and pump reliability. The client selected three concepts: coverage optimization, research and selection of fogging nozzles, and research and selection of a chemical pump. The team conducted the necessary research and selected a nozzle type and a pump based on pressure and flow rate capabilities. The pump chosen out of 4 different categories of pumps was a magnetic drive pump, the HP Mag-Drive Pump Model HP75MD manufactured by Price Pump Co. Four different shower layouts were then presented and a final shower layout was chosen. The layout uses 3 Minifogger III nozzles for spraying MCP and 2 FogJet nozzles for rinsing the suits. Bernoulli's equation in conjunction with Reynolds number calculation to calculate major and minor pipe losses for a series of different pipe diameters and wall thicknesses. To optimize head losses, a 1" pipe with 0.065-inch wall thickness was selected. These pipe dimensions produce laminar fluid flow and combined pipe losses of 0.113 feet or 0.0491 psi. Lastly, the fail-safe pressure and flow rate were analyzed. The new design uses 0.18 gallons of MCP per shower per cycle, and 5.72 gallons of water per shower per cycle. This presents 93.2% of water savings, and 99.5% of MCP savings.
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Mechanical Engineering