matt switzer (me) tyler josselyn (me) evan hall (ee) phil...
TRANSCRIPT
Matt Switzer (ME)
Tyler Josselyn (ME)
Evan Hall (EE)
Phil Floroff (EE)
Faculty Guide: Sarah Brownell Customer: Fermin Reyegadas, Fundacion Cantaro Azul
Overview • Project background
• Planning
• System design
• Testing
• Conclusions
• Recommendations
• Questions
Project Background
• Existing UV water treatment system
• Gravity fed
• Weak local power grid
• Objective:
– Detect failure & protect clean water
Customer Needs • Prevent contamination of clean
tank during given failure modes: -Power outage -Brownout -Blown UV bulb • Warn kiosk operator of failure • Allow for independent UV
chamber operation • Made from materials available
in Mexico • Require few consumable parts • Maintain 5 L/min flow rate per
chamber • Low cost solution
Engineering Specs
System Architecture
Control Board (PCB)
Irrigation Valve 1
Irrigation Valve 2
Water Flow Control
UV photodiode 1
UV photodiode 2
Failure Detection
Warning Speakers
LED System Indicators
Operator Interface
Valve Assembly
• Irrigation valves
• Solenoid/diaphragm
• Low flow, low pressure operation
• Fail Closed
• Easy integration
Dual irrigation valve assembly
Electronics
• The printed circuit board shown here controls the valves and warns the operator that there is a failure
• Requires some trained assembly (to be assembled by PCB assembly service)
Electronics Enclosure
• The PCB was designed to fit into a small conduit box that can be mounted in the kiosk, near the valves
• Speakers and LEDs are mounted externally on box
Photodiodes
• Capable of detecting all failure modes
• Design allows system prevents flow restart until safe level of UV output is reached
• No UV Chamber draining will be necessary
• Automatic restart after power loss
• Simple installation in chamber
Photodiode
UV Bulb
Warning the operator
• Failure – Speaker sounds and red LED lights, both powered by 9V battery
• To turn off the speaker and red LED, the operator can flip a switch
• Once the problem is fixed, a green LED will light, the switch is flipped back
• The system also includes an amber LED that turns on when the battery voltage is low
Speaker
System Ready Switch
Test Rig
• We built a test rig to simulate the gravity fed system in the actual kiosks
• The two irrigation valves run in parallel to two UV chambers
• We are able to simulate a power failure by pressing the red button seen to the left
Test Results
• Gravity fed system achieved a flow rate of 4.5 L/min
• Inlet/outlet height differential must be >4 ft.
• Circuit board closes valve when UV light is not present
• Speaker/LED gets attention of operator at > 8 meters
• Backup alarm/LED will run for 17 consecutive hours on one 9V battery
• Valves seep 15.5mL/hr average
Budget
MSD Costs Budgeted Actual
Test Stand (tanks, pump,
structure) $400 $184.39
Electrical (wire, circuits,
PCB) $100 $202.63
Plumbing (Pipe, flow stop
mechanism) $100 $63.10
Total $600 $450.12
Costs to Customer Quantity Total Price
Valves 2 $34.10
PCB 2 $66.00
Photodiodes 2 $44.88
LEDs 6 $1.96
Speakers 2 $4.58
Wiring As
Necessary ~$10.00
Assembly - Need Quote
Other Parts - $40.71
TOTAL per Kiosk $202.93
Conclusion: Successes • Independent chamber operation
– Using two independent circuits
• Under budget
• LEDs and speakers will get operator attention
• Valves stop water flow
• Auto-restart when safe UV output level sensed in chamber
Conclusion: Challenges • Valve leakage due to dirty diaphragm
• Mousetrap valve concept
• Getting system to work on one circuit
• Speakers not as loud as expected
• Couldn’t incorporate rapid power on-off delay • Deemed unnecessary
• Customer will not be able to fix electrical issues in field
• PCB assembly for customer
Recommendations
• 2 independent circuits
• Periodic diaphragm cleaning
• Test correlation between UV output and photodiode voltage
• Valves located close to UV chambers
• Upon install, ensure valve seals water flow
Questions?