28 July 2014
Below are the full instructions on how to build exactly what I built. There is so much that could be done to improve the design. I know it is not anywhere close to perfect. The materials I used were makeshift, whatever was lying around the house or wasn’t too expensive. But that was the point. I like spontaneity. It doesn’t have to be extremely elaborate to work and to be useful. This is for anyone who wants to do anything with it or for anyone who is just interested.
1. Vernier Flow Rate Sensor, Order Code: FLO-BTA/FLO-CBL
2. Vernier Lab Quest by Vernier Software and Technology.13979 SW Millikan Way, Beaverton, Or 97005. 888-837-6437. (for transmitting and collecting data from the Flow Rate Sensor.)
3. 3 22” steel dowel rods
4. Compressed fiber board
5. Minwax Polyurethane Varnish
6. 24 Gauge- 100 ft. Green Floral Wire Twister
7. Small foosball
8. 2 IDEC Sensors, Magnetic Proximity Switches. Type: DPRI-019. Premium Waterproof Clear Silicone Sealant (without Acetic Acid)
10. Plugable USB to RS-232 DB9 Serial Adapter (Prolific PL2303HX Rev D Chipset)
11. RS232 Breakout - DB9 Female to Terminal Block Adapter
12. Xnote stop watch, version 1.66 (downloadable at http://www.xnotestopwatch.com/)
13. Loctite Epoxy glue
16. 2 Brass quarter inch Phillips Head screws
17. Electric hand held reciprocating saw
18. Electrical tape
19. 4” by 3/4” strip of thin steel (cut from a can)
20. Twisted Nylon string
21. 2’ long wooden slat (to be used as a handle for carrying and placing the designed device in the water.)
22. Study Site: United States Geological Survey (0164900), Northeast Branch of Anacostia River at Riverdale, MD. (Test site was just next to the USGS data collection gauge.) (-38.961, -76.626)
Building the device:
1. Two identical wooden rings were cut from the compressed fiber board using the reciprocating hand saw. The circumference measured at 2.5”, the thickness (which was just the thickness of the original board) at .5”, and the width of the ring at .5”.
2. Three identical holes on the cross sectional sides of each ring, 120 degrees apart were drilled.
3. Each ring was thickly coated with the Minwax varnish (for waterproofing) and then left to dry. (multiple coats were applied)
4. One ring was placed on either end of the three dowel rods (one through each of the drilled holes), yielding an open track for water to move through.
5. The three dowel rods were secured to the rings with the epoxy glue.
6. One proximity sensor was screwed horizontally onto the interior face of each ring, directly between two of the metal rods and directly opposite each other along the length of the track.
7. A thin layer of silicone sealant was applied directly to all surfaces of the sensors (for waterproofing.)
8. Each of the sensors had a long cord with two exposed wires sticking out at the end (one white and one black.) The two white wires (one from each sensor) were screwed into the 7 pin on the breakout board and the two black wires were screwed into the 8 pin.
9. The multi pronged wide end of the USB connector was then plugged into the Port on the breakout board. (the other end was later plugged into a computer which supplied the data.)
10. The electrical connection between the sensors cords, the breakout board, and the USB connector was then secured and partially protected with a wrapping of electrical tape. (to protect from water droplets, but NOT fully waterproof.)
11. Two small holes were drilled on each of the wooden rings, just above the magnetic sensors on the curved face of the ring.
12. Through each of these holes a tightly wound thread of 24 gauge twister was strung. (The tops of these wires were secured together with epoxy glue.)
13. Running the length of the track, the wooden slat was secured with electrical tape through the wound wire twister handles.
14. A nylon string was tied to either end of the wooden slat to be used as a device for lowering the system into the water.
15. The steel strip cut from a can was then tacked to a hard plastic foosball (about an inch in diameter); one end on one side of the ball and one end on the opposite side of the ball. This yielded a tall metal loop protruding above the original height of the ball on either side.
16. Two 1” sections of heavy plastic drinking straw were cut on one side each so that they could be slipped over and onto two of the steel rods.
17. Then, two pieces of straight coat hanger wire (about 2” long each) were set across the rails through the loop from one straw to the other and glued in place with silicone sealant to the top of the foosball (just below the loop.) This created a freely moving object for the track.
Taking the Data:
First, the speed of the stream was measured with the Vernier Flow Rate sensor. The speed was measured at approximately 60% of the depth. The Vernier Flow Rate sensor transmitted continuous data which was automatically stored in a graph on the Lab Quest data processor. (speed vs. time for 3 minutes each)
Secondly, the same procedure was with followed with the designed device which transmitted individual data points to an excel spreadsheet which was later compared with the Vernier data. The USB connected to the device was plugged into a computer and used through the Xnote stopwatch timer program. When the device entered the water the moving object was pushed from one end of the track to the other which sent a signal through the magnetic sensors to the timer program which measured the time it took for the ball to travel the length of the track. The speed was computed by dividing the length of the track by the time it took for the traveling object to move from one sensor to the other.
This experiment looked for a significant difference between the Vernier data and the experimental device’s data. Data was collected in two separate outings. On the first day, 50 speeds were computed with the designed device and 5, 3-minute, continuous runs of data were taken with the Vernier device. Then a design change was made to reduce friction (resulting in the device described earlier.) On a second day, 25 speeds were computed with the designed device and 3, 3- minute, continuous runs of data were taken with the Vernier device.