P14417: B9 Plastics - Particle FilterSubsystem Design Dan Anderson / Thomas Heberle / Perry Hosmer / Karina Roundtree / Kelly Stover October 29, 2013
Engineering Metrics & Specifications: Functional Decomposition: *Items in Red are Metrics and Specs that map to Customer Requirements or Risk Assessment Tasks
Water Characterization • Key metrics for consideration: • Turbidity: “cloudiness or haziness of a fluid caused by individual particles, normally invisible to the naked eye.” • Total Suspended Solids: measurement of water quality, dry weight of particles that would be trapped by a filter. • Water source used: Genesee River Water • Represents possible use conditions in the developing world. • Used as litmus test for Better Water Maker to determine process improvement.
Water Characterization • Resource contacted: Dr. Scott Wolcott (RIT Professor) • Testing: Several samples were taken from the Genesee during varying conditions that could affect turbidity and TSS. • Three samples collected and tested. • Gen 1: Collected Oct. 5th, hadn’t rained in a while, tested on Oct. 19th. • Gen 2: Collected Oct. 18th, moderate rain, tested on Oct. 19th. • Gen 3: Collected Oct. 23rd, frequent rain preceding days, test on Oct. 24th. • Also considered brewery waste water provided by Dr. Wolcott in analysis.
Water Characterization • Possible sources of error: time between insertion/removal from oven, minor spillage, etc.
Identification of Critical Subsystems Mesh Fasteners Seal Sandwich Assembly Outer Walls
Materials • Cheese Cloth • #90 grade(44 x 36 Vertical x Horizontal threads per inch) • Cheap and easily adaptable • Not easy to clean effectively • Plastic Mesh • Cheaper • Not as small a mesh • Easily deformable • Stainless Steel Mesh • Small mesh size • Durable
Stainless Steel • Stainless steel is in a family of alloy steels containing a minimum of 10.5% chromium. All stainless steels have a higher resistance to corrosion than their mild steel counterparts. • This resistance to attack is due to the naturally occurring chromium-rich oxide film formed on the surface of the steel. • The film is rapidly self-repairing in the presence of oxygen. Damage by abrasion, cutting or machining is quickly repaired.
Flow Rate Considerations • Specification from supplier for 5 micron stainless steel mesh • Flow = @ 1 psid (pressure difference) • Approximate diameter of S.S. mesh = 30 cm = 11.81 in • Q @ 1 psid = 555.6 L/min
Flow Rate Considerations • Comparison and Conclusions: • ΔP, in this case = 1 psi = 6,895 Pa • Based on new specification for flow rate (Q= 0.394 L/min), we would achieve 14,102 times the marginal flow rate value. • It can be concluded that using 5 micron steel mesh is a good course of action to reach desired flow rate. • Max ΔP in our case is approximately 2,632 Pa • Assumes max possible volume in upper bucket = 5 gallons • Using approximate dimensions for the filter assembly (i.e. D = 30 cm)
Flow Rate Considerations • Max possible pressure = 2,620 Pa, about 2.6 times less than the pressure difference used in the S.S. specification. • Pressure is a function of open area available (diminishes through clogging of filter) and weight of water above filter. • Difficult to determine a mathematical model since there is some inherent variable in the water properties.
Test Plan: Flow Rate • Use available “pond pump” to generate a steady flow of a known rate over a simple filter mesh assembly at Genesee River. • Determine based on rate of pump output, how long it will take to introduce five gallons of water to assembly. • Determine adequacy of five micron Stainless Steel mesh. • Introduce filter complexity to improve process.
Stress Testing Fw=pVg=185.7N Fs=pVg=1826.5N Pmesh=(Fw+Fs)/Amesh=48.83kPa
Cleaning • Cleanliness is essential for maximum resistance to corrosion. • Never use abrasive powders or materials on stainless. • Always use a soft cloth. • Mild detergents and soap can be used but those containing chloride detergents should be avoided.
Risks • Bacteria forming on sand • Rapid sand filtration - 20m/hour • Chemically pre-treated • Slow sand filtration - 0.4m/hour • Just scrape off the biofilm on sand surface
Seal Considerations • Type of seal application: • Low temperature – T max = 120ᵒ F • Low pressure: W water, max = 185 N = 41.6 lb • Need two seals for top and bottom of sandwich assembly • Desire low compressibility • Supplier Contacted:
Seal Considerations • Determination: Rubber Gasket application • Example:
Seal Considerations • Specifications: • Max Temp. = 200 F • Max. Pressure = 250 psi = 1.724 MPa • Supplier will give us free gaskets upon completion of detailed design drawings, cut to our specification.
Seal Considerations: Test Plan • Use standard gasket “sealability” test: ASTM F37 -06 • Testing capabilities available through Garlock
Component Feasibility Other Key Components
Fasteners • Fastener Materials with high resistance to weather and/or corrosion: • Stainless Steel • Titanium • Brass • Bronze • Of these four materials, Titanium is the most lightweight. But considering the costs of each, stainless steel is the most feasible material to use in our Filter. Fastener Choice is dependent on the design requirements and the environment in which the fastener will be used. • Threaded vs. Non-Threaded • Non-threaded is not ideal for continuous dis and reassembly • Threaded fasteners provide ease of assembly and reusability without much wear. • Two main threaded fasteners: • Nuts & Bolts • Screws Summary: We should use stainless steel bolts with wing nuts. The wing nuts allow for tool-less dis and re-assembly, which is a great convenience in our application. ***Although this may not be necessary if captive or welded nuts can be used.
Water Usage Average of 2.6 liters / day / person needed Therefore a family of 5 needs 13 liters or 3.4 gallons / day
Lifting Task Used NIOSH Lifting Equation to evaluate the feasibility of the task Assumption made on height of media Recommended Weight Limit: 33.5 lbs 3.4 Gallons of Water ~ 28.4 lbs 5 Gallons of Water ~ 41.7 lbs* *Lifting Index: 1.25, slight risk for low-back pain or injury
Detailed Design: Diagram of Activities Proof of Concept Risk Assessment (Detailed Design) Engineering Analysis Component Selection Detailed Design Demonstrate feasibility and meeting specifications Make/Buy Decisions Complete Bill of Materials Simulation Models • Hardware Design • Complete Drawing Package • Assembly Process • Bill of Materials • Budget Overview • Risk Assessment • Testing Plan (for MSD 2) Input from Eng. Analysis & Research. Demonstrate the more experimental and/or derived metrics and specs. Budget Review of BOM Part Drawings Ensure the proposed design can be completed with the Budget constraint. Assembly Drawings Test Plan Develop Assembly Process Detail test procedures to be executed in MSD 2: Build & Test. Design for manufacturability, cost, & repeatability (assembler perspective).