Flow

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Controller

Linearization and Calibration

Abstract

Experiments run in fall 2007 indicated that the float valve can hold back head of at least 8m with less than 0.5 cm of change occurring in the flow controller water level in the first 2 m of pressure. Data gathered in the laboratory on outflow rate has followed a linear model in the laminar flow range, but attempts to model the turbulent transition range have produced varying results. It is considered a high priority to develop a reliable model for dosing at higher flow rates, which will be used in the near future at the larger plants.

Keywords: Flow Controller, laminar flow, height of outflow, influent pressure, float valve

Introduction and Objectives

Constructing reliable and cost-effective solutions for water treatment in Honduras is challenging due to the lack of infrastructure. Electricity is unreliable, which has rendered modern computer-automated water treatment plants unusable, moreover the mountainous terrain sometimes makes access to materials needed for construction or repairs difficult. While it does isolate villages and their utilities, the rough topography has created an opportunity for the use of gravity-powered treatment plants. There has been success with the implementation of AguaClara researched and designed flocculators that are mixed by gravitationally-derived kinetic energy, but chemical dosing in these plants without the use of electric pumps is still inconsistent.

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Other aspects of flow controller performance have also been tested this fall, including maximum inlet head allowable, water level variation in the flow controller, and corrosion resistance of the manufactured float valves. There have also been updates made to the materials used in the flow controller design.

Conclusions and Areas for Further Research

Through this semester the Flow Control Module testing apparatus has evolved to allow more precise testing to take place. The next upgrade to our testing equipment is an automated position control, which will be capable of changing the head loss in the system automatically. This will increase the precision and quantity of data collected in the future.

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