K500 Manual

The K500 is an emriver closed loop liquid flow controller. It uses an AW Lake paddlewheel sensor and a GRI brushless DC water pump, as well as a 2x16 character LCD screen and optical encoder.

The main menu is where the operator sets the desired flow in Ml/s. They do this by twisting the knob left or right. Speed at which the knob is being rotated is proportional to the speed at which the setpoint in ml/s is adjusted. Faster rotations lead to rapid adjustment. 0 Ml/s indicates no flow. < 55 Ml/s indicates flow, but is below the operation point of the paddlewheel sensor, so accuracy is not guaranteed. This can be verified by the lack of a moving paddlewheel indicator in the top right corner of the screen. Other flows 55 Ml/s can be set, and the closed loop control portion of the code will run. This closed loop constantly detects the difference between the setpoint chosen by the operator, and the current measured flow from the paddlewheel. It makes large adjustments to the output that controls pump speed if the magnitude of the error is large, and small adjustments when the magnitude of the error is small. The closed loop control can be verified by observing the moving paddlewheel indicator in the top right corner of the screen. When introducing a change to the setpoint of the system the following behavior is expected: The controller rapidly adjusts the flow rate of the pump until it overshoots the desired setpoint slightly. The flow rate is dialed back until it settles around the setpoint and maintains this flow level by constantly making micro-adjustments. It is also resilient to disturbances such as changing head (height between the pump and the outlet) when the slope of the tilt base models are adjusted.

Also, the system can run without the paddlewheel connected at all. Either disconnect the sensor from the controller, or bypass the tubing that goes to the paddlewheel. The controller checks for the time since it has last detected input from the paddlewheel sensor. And can easily change between closed and open loop controls. This alternative mode is less accurate, and is recognizable by the lack of the moving paddlewheel indicator in the top right corner of the screen.

Pressing the button on the optical encoder pulls up the main menu. Use the encoder twist to navigate between menus. There are shortcuts to stop flow, maximize flow.

A built-in hydrograph function can be accessed through the menus.

These simulate scenarios such as floods, and take control of the setpoint at 30 second intervals during their duration. They can be cancelled by pressing the encoder button. New hydrographs can be programmed into the code and uploaded to the controller. Instructions for doing so are in the code.