By Sean Schwartz
Patoka Lake Regional Water & Sewer District (PLRWSD) serves 11 counties in southern Indiana with a population of around 130,000. The distribution of water travels though approximately 850 miles of pipe ranging in size from 3” to 30” and includes numerous elevated towers or tanks in each District Metered Area (DMA). The treatment facilities are fed by an intake structure located at Patoka Lake a little over 1 mile from the water treatment plants. Sean Kluesner is Operations Manager and Jerry Allstot is the Plant Superintendent for the District.
A recent plant upgrade designed by Midwestern Engineers nearly doubled the size of the treatment plant’s capabilities and increased the size of raw water pumps at the intake structure. With a complex network of pipes, booster-pumping stations, tanks and reservoirs required to move the water from the treatment facilities to the customers, several Singer control valves were selected to maintain the pressure in each DMA.
To prevent surges when starting and stopping the pumps, PLRWSD selected two bypass pump control valves. These control valves are installed in a tee between the pump discharge and the check valve. The valve is normally open, and on pump start-up, the valve discharges air, water and sand to waste. The open valve discharges all pump flow and then as the valve slowly closes, flow is smoothly transferred to the main line, increasing the pipeline flow without surges. When the valve is fully closed, all pump flow is in the pipeline with no control valve losses.
In addition two 12” flow metering valves with internal drop check features, controlled by multi-process control panels with touch panel interface (MCP-TP), were selected to be used downstream of the pumps. These valves were chosen for several reasons: First, there is an internal drop check feature that closes the valve should you have a reverse flow situation. This eliminates the need for a check valve downstream as well as a hydraulic overriding pressure reducing pilot to ensure the system doesn’t over-pressurize downstream. However the main reason for using these flow metering valves in this application is that they have the ability to measure flow as well as control flow when partnered with the MCP-TP control panel. These features give the user the ability to program varying setpoints of flows during the day. “Setting the setpoint is very easy, just type in a flow setpoint on the touch screen and the controller takes care of the rest,” explained Ryan Spooner of Singer Valve. This is especially cost effective for lower flows during off peak times of the day as there is no shutting down of the pumps, which would add cost.
PLRWSD also needed a valve solution to handle the additional flows to multiple water plants equally. One option was to use an existing 14” valve and add another new 14” inch valve in a side-by-side arrangement using position control to drive open both valves equally. However this was determined not to be the best solution: because of the varying length of pipe, the location of the valves and the amount of 90 degree bends before and after the valve locations, each valve would not equally flow. In addition PLRWSD is still planning for a growing population, which this setup would not have accommodated.
After much consideration, FloSource suggested a larger 24” control valve partnered with an EPC-4XF control panel and X156 position transmitter for valve position indication. The EPC-4XF main function is designed to complement a dual opening and/or closing solenoid configuration with quick and easy configuration for any single process application. The controller reads and compares the process feedback to the desired setpoint, then accurately positions the valve to bring the process variable toward the setpoint until they coincide using a PID control loop. The EPC-4XF is equipped with the dual opening and/or closing solenoid configuration referenced above, as well as an additional solenoid for shut-off/override.
Choosing the right valves for each application is critical and having the ability to tweak each valve with various backup features and remote control options gives Patoka Lake the flexibility to manage their water distribution effectively. The upgrades will allow the city to grow and welcome new residents with reliable water flow.
About the Author: Sean Schwartz is an account manager for Singer Valve with extensive knowledge on installation, start up and specification of automatic control valves for a wide variety of applications for potable and reclaimed water applications with control valves. He is a certified instructor for the Singer Valve Automatic Valve Application and Operation Training Program held in Charlotte, N.C.
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