Experimental Methods

The first experiment conducted was a simple corrosion test for the manufactured float valves. The float valves are mostly plastic, with a stainless steel screw and pivot pin and a rubber pad that shuts off the inflow when the float rises. The pivot pin creates the joint that the float valve rises around, and if that fails then the entire float valve fails. The rubber pad is of similar importance in that if it fails then the inflow cannot be plugged and regulated. An entire float valve was placed into 120 g/L alum solution and a second entire float valve was placed in 13 g/L hypochlorite solution. These are the concentrations used in the AguaClara plant in Ojojona. The float valves were checked every week and observations were made regarding apparent wear and corrosion on the various exposed parts. The alum and chlorine solutions were replaced every week to ensure that the chemicals did not lose their reactivity. While the continuous chemical submersion is more extreme than normal operating conditions, it showed which parts of the float valves tend to fail first under exposure. Those parts can then be replaced with more corrosion-resistant counterparts to improve the life span of the float valves.

Experimental Results

The corrosion test was conducted for five weeks. There was no visible corrosion to the float valve screw, pad or pin in the alum solution. After a week, the float valve placed in the chlorine solution had severe visible corrosion of the screw, but no visible corrosion of the float valve pin or pad in the chlorine solution. Although the chlorine and alum solutions were replaced every week to maintain reactivity, we were uncertain of how reliable this data would be. The flow controllers in place in Honduras are continually supplied with fresh chemicals and they are constantly monitored, so we are deferring data collection on float valve corrosion to the plant operators and engineers in Honduras.

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