What Does Demand Dose Mean?
In this article, we’re going to help you understand how your demand dose panel works. First, we’re going to explain what demand dose means. Then we’ll walk you through how simplex and duplex panels work in a typical system. Let’s get started.
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Safety Note: Please use caution while handling your pump control panel. We have designed them with the highest safety standards in mind, however they are complex electronics and can cause death or serious injury if used improperly. Only follow the instructions provided and contact our support team if you are unsure of what to do.
What Does It Do?
Demand Dose panels turn pumps on and off based on the water level in the pumping chamber. They can also trigger an audible/visual alarm, letting you know when the water reaches a certain level. SJE Rhombus demand dose panels come standard with Hand Off Auto (or HOA) switches for mode of operation. Hand operation allows the user to manually run the pump. Off prevents the pump from turning on. Auto is the mode of operation that allows the floats in the tank to dictate when a pump should turn on and off.
How Simplex Demand Dose Panels Operate
Simplex panels control one pump using 3 control floats: Stop, Start, and Alarm. When the water level rises in the pumping chamber and lifts the two lower floats (Stop and Start) to the on position, the control panel calls the pump to run, lowering the water level. The pump continues to run until both floats lower back down to the off position. The distance between the Stop and Start floats determines the pumping range, or the vertical water column that is discharged each time the pump is called to run.
If the pump is unable to keep up with the liquid demand and the level continues to rise, the alarm float will rise to the on position, activating the audible horn and visual beacon. The alarm will remain active until the alarm float lowers down to the off position. You can press the Silence Test switch to the silence position to deactivate the horn for the current alarm condition. Pressing the Silence Test switch to the test position when the panel is not currently in an alarm condition will activate the beacon and horn to test functionality.
How Duplex Demand Dose Panels Operate
Duplex panels control two pumps using either 3 or 4 control floats. Your application will determine which set up will work best for you. First, we’ll discuss the 4 float system.
4 Float System
The four floats are: Stop, Lead, Lag, and Alarm. When the water rises in the pumping chamber and lifts the two lower floats (Stop and Lead) to the on position, the control panel calls pump 1 to run. The pump continues to run until both floats lower back down to the off position. The next time the pump is called to run, the control panel will call pump 2 to run. It alternates between the two pumps every other cycle, equalizing pump wear.
If one pump is unable to keep up with the liquid demand and the water level continues to rise, lifting the Lag float to the on position, the panel will then call both pumps to run simultaneously. Once all the floats lower down to the off position, the control panel will reset itself to a single pump alternating mode of operation.
The position of the alarm float in this system depends on the application. For septic pump stations or lift stations, it is recommended to have the alarm float level lower than the Lag float level, as this will provide alarm notification before your panel goes into Lag mode. In certain situations, it may be appropriate for the Lag float to be below the Alarm. Please note that using this set up will not provide alarm notifications unless both pumps are unable to keep up with the liquid demand and the liquid level continues to rise.
3 Float System
Our duplex demand dose panels are designed to also operate with a 3 float system: Stop, Lead, and Lag/Alarm. Using the three float setup will have the Lag and Alarm functions activated simultaneously with the use of a single float.
Conclusion
Now you understand the theory behind how your demand dose panel works! If you have any questions, please contact our customer support team at techsupport@sjeinc.com or at 1-800-746-6287.
