Pong Device HJR Environmental Heather Nelson Jeannette Harduby Rudi Schuech HJR

Project Goals To design a constant flow control device capable of handling turbid water –Easy to operate and maintain –Not prone to clogging –Inexpensive to build Build and test preliminary model Analyze data and make recommendations for further research

Collection Chamber Flexible tubing Removable adapters w/ internal mesh screens Sand pipe Sealing pipe Pong pipe Tubing-pipe adapter Dramatization. Actual droplets may be smaller. Head that ping pong ball must retain Driving head for sand column Height of sand Initial water height Perforated Baffle Pour water in here What happens when user stops adding water?

Sand column HJR Holding container (bucket or glass column) Pong pipe Sealing pipe Driving pressure for sand column Upflow prevents trapped air (keyword: “prevent”)!

Force Balance θ2θ2 θ1θ1 RsRs RpRp RpRp RpRp LsLs sealing pipe (not to scale!) Static pressure force = γH 0 L2L2 L1L1 R p - L 1 R p - L 2 V d1 V d2 V c2 V c1 Volumes of top and bottom spherical sections are V p2, V p1 H0H0 Total pressure head ≈ 25 cm → Sealing pipe diameter = 7 mm! Does it leak? Not really – leaks about 7 mL/day (.04% of 20 L/day target!) Ice cream = Ice cream cone – cone !

Sand column 1 2 L Assuming # pores = # sand grains, and Porosity = θ = V pores /V total = A pores / A total …… z 1 -z 2 = h L ! 10 cm h L → 20 L/day expected 1.5 cm → sand diameter < 0.4 mm

Clean Water

Dirty Water (150 NTU)

Testing Conclusions Pong Device very sensitive to movement, needs to be designed more rigidly Flow rate fluctuates over time Possible cause: air bubbles forming in tubing – sand column needs to be shaken approximately every 6 hours With dirty water flow rate decreases steadily over time

Further Reflections Bubbles won’t be a problem when water is at equilibrium with outside temperature

Recommendations Develop rigid Pong Device design Test in field conditions Contact NGO’s and other organizations working on similar research projects to fill gap in primary sources

Questions?