Skype with Jeff:
On the topic of Variable Dosing:
Most of the people in the area are using 10 or 20 L jerricans, so if we were to do variable dosing it would be fine if it just handled these two options. User choice would be good, but don't get too focused on it.
If we decide on only one setting, it is better to dose for 20 L.
There have been cases of both intentional and unintentional misdosing. Some people don't realize that they aren't dosing properly while others are worried about over-chlorinating their water and therefore dose less than they should.
+So if variable dosing isn't important, what is important?+What's important: Having a mechanism to dispense liquid.
We talked about our idea for a Soap Dispenser àHe said it was cool, that they had tried it and had trouble picking up all the chlorine, and that there we brought up concerns about durability.
Precision of dose is very important. Need accuracy within health specifications of CDC/WHO (not by taste or any other parameter). The target amount is approx. 3 mL.
+A History of Dispensers:+The Initial Prototype: A Soap Dispenser àIt had inaccurate dosage, leaking, and degradation.
Then: Ball Valve à .5 inch diameter. Plastic broke down over time because of contact with chlorine. They then had a custom one made out of resistant to chlorine material.
Cost for the current valve:Long-term would have mold. Cost goes down.
+Some other Questions:+Do we have Injection molding?
Yes, they would have access to injection molding if needed.
Jeff commented on another problem with a valve (I'm not sure if this was the current valve, or a valve idea we suggested): The surface tension. He said he had to bang on the dispenser to get chlorine to come out. We should keep in mind surface tension.
As far as the concentration of chlorine goes:
If we made the dosing half the volume and increased the concentration twice as much that would be fine.
Where will it be manufactured? Valve = imported from China or brought from capital city.
Everything else should be cheap and easy to repair/maintain.
They could obtain materials from the town to bring to rural area. Or assemble the dispenser in town.
User knows when tank is running low.
Ideas we discussed: Plastic membrane. Flexible refill container (bag/bladder/Carboard for milk).
Materials that are locally available:
Standard plumbing things.
Plastic jerrican from 1 L to 25 L à20 L = 50 cents. Smaller can could be 20-30 cents. And used jerricans can be sold, so that could be a good container for chlorine. Sell once chlorine is used up.
Plexiglass, sheet metal, scrap metal.
Nuts and bolts. Hinges.
Wood, scrap wood.
Repurposed tires cut into strips
Plastic Bags.
Hosing --> Could order a variety from local areas.
Jeff said they have tried 6 and 8 inch diameter PVC pipe as well as using plastic jerricans.
He'd love for us to have an environmentally friendly system àConnect refill bottle and tank bottle.
The all-purpose valve (attach it on any container) would give us accurate precision + durability. If we could do it, it seems like a good idea.
PVC (up to 8 inch diameter) and Plastic used in jerricans will not degrade with chlorine contact.
Injection molding would be considered Total Cost/# of units
+More History:+Started with valve on the ground. No one likes lifting water. Then realized that for efficacy, it doesn't matter if chlorine or water goes in first.
The current process, they take an empty can, put in water, swoosh around, dump out, add chlorine, fill with water.
The shade stand.
First Shade stand -->Flat top = bad! -->House rooftop had lost of metal.
Then tried conical shape.
Now, no shade stand needed àCan use wood and plastic if desired. We should take advantage of this!
Start-up Cost
Chlorine refill -->Container = big part of cost.
-->Sell refill container would be great!
--> 8 x more expensive for tablets. Cheaper tablets suffered expense in terms of shelf-life.
Nearby pharmacist would have refill can. Stores carry small sizes. Buy 16 and sell for 20. Markup.
We would sell to a wholesaler who would then distribute it to lots of stores.
Household treatment --> Failed.
Community treatment -->Expensive and difficult to maintain.
Chlorine remains in water for 12-24 hours it prevents against recontamination. Dirty container still allows for clean water.
More concentrated solution -->Same time.
For now, acceptable range is +/- .5 mL.