Flow Controller

Linearization and Calibration

Introduction

The Flow Controller device is used to maintain a constant level of water in a source, a constant head tank, which is refilled by a stock tank. By adjusting the constant head tank, different flow rates of Alum may be sent to the plant for the flocculation process. Field use of this device, however, is consistantly inaccurate, diverging in direction relation to flow rate as well as tubing length. However, the majority of the data seems to indicate that are are infact more confounding variables which make flow predictions nearly impossible. This dependence on faulty information, namely the inapplicable equations, may cause miss-dosing in the plant or a wasteful situation of using too much Alum for the plant.

Divergence specifically occurs to cause under delivery of alum to the plant, which decreases the efficacy of flocculation and has an adverse affect on effluent turbididty. This section of the Flow Control Module Team is conducting tests to identify confounding variables to more accurately parameterize the equations to provide for more efficient flocculation in the plant.

Goals

This team is working specifcially with the constant head tank as a distribution system with known parameters and an adjustable arm for dosing providing a known head loss from elevation. First it is important to verify that the tubes in use do, in fact, meet the specifications of smoothness and diameter. Once we are sure that the material is regular, and if not, once we may correct for this difference, it is important to see what the trend is in divergence from the Hagen-Poiseuille equation. Graphing of flow rate vs. Headloss allows for a simply relationship between the experimental and theoretical. Once these have been parameterized for the purposes of calculation, it will be useful to continue looking into possible sources of headloss through the system or any factory that may deter flow.

Additional Documentation

The Linearization and Calibration Quiz- find out how much you really know about this flow controler sub team.
Linearization and Calibration team goals and meeting minutes.

Methods and Results from Specific Experiments

Flow Rate vs. Headloss for Variable Tube Lengths
*Taking the new aparatus, flow rates were calcualted relative to head loss and plotted again the Hagen-Poiseuille equation to anazlye divergence from the mathematical model

Diameter Corrections
*Calculate the inner diameter of the black tube used for dosing to ensure accuracy in dosing

Float valve corrosion test

• A simple test where float valve parts were left in alum and chlorine for extended periods of time to determine corrosion effects

Flow controller body design and selection

• Includes notes on the brainstorming that went into FCM parts selection and design

Flow versus head loss data collection in the turbulent range

• 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

Fall 2007 Final Report

• Background on previous research

Conclusions

Based on the work so far, it may be concluded that there are variables that are causing significant distortion between experimental and theoretical results. Also, this may be attributed to manufacturing, due to its strongly correcting aspect interms of the equations. Additional conclusions as they relate to future topics may be found [here|FC LinCalib-Sp09 Callenges].