*** This version of Confluence is for testing only and contains a copy of content from June 29th 2026. No changes will be preserved. ***
...
- Includes notes on the brainstorming that went into FCM parts selection and design
Flow versus head loss data collection in the laminar range methods
Flow versus head loss data collection in the turbulent range methods
- Experiments were conducted to establish a model for the relationship between FCM outflow and headloss associated with outflow tube position
Determining the maximum inlet shut-off pressure
...
- The maximum inlet pressure that the float valve can shut off was investigated in order to determine how much head there can be between the chemical stock tanks and the flow controllers
...
This data was analyzed in Excel to determine maximum shut-off pressures and change in flow controller water levels. The data for each float angle orientation was analyzed separately to determine an ideal angle to use in the AguaClara plants. The data was also manipulated to see if the water level in the flow controller would vary greatly enough to significantly impair flow controller function as a stock tank would drain in a plant.
...
Results
Float valve corrosion test 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.
Flow versus head loss data collection in the laminar range results
Determining the maximum inlet shut-off pressure results
The maximum inlet pressure that the float valve could resist was determined. Float orientations of 90, 45 and zero degrees all resisted a pressure of at least 8m. A float orientation of zero degrees resisted pressures of at least 11m. All of the float orientations have a maximum inlet pressure well above the 2m needed for the AguaClara plants.
This data was further analyzed to also determine the amount of variation in flow controller level with increasing pressure build up on the float valve.
The level in the module changed by many centimeters during the experiment, but this was over the entire range of inlet pressure build-up. For the range that is pertinent for designing AguaClara plants, up to at most 2m, the level changed in the flow controller much less. The table below shows the total change in flow controller water level at both the highest back pressure reached, and at approximately 2m of pressure.
| 0 Degrees Float Angle | 45 Degrees Float | 90 Degrees Float |
|---|---|---|---|
Water Level Change at 2m Pressure | 1.2 cm | 0.4 cm | 0.35 cm |
Total Water Level Change | 2.4 cm | 1.2 cm | 0.9 cm |
Positioning the float straight out from the valve caused the most variation in water level, while positioning it at an angle of 45 degrees or 90 degrees had about the same effect. Currently the floats are positioned at an angle somewhere between 45 degrees and 90 degrees to best fit inside a small flow controller. Assuming this positioning is kept, the variation in water level is large enough to influence the outflow by effectively causing error in the expected head loss in the system of up to 0.4cm. While this does create a discrepancy between assumed and actual head loss in the system, it is much smaller than the uncertainty caused by a draining stock tank.
Inlet Shut-Off Pressure Procedures
Conclusions and Areas for Further Research
...