Not every chemical dosed at a wastewater treatment plant needs to run continuously. Shock disinfection, digester biocide addition, and sludge-conditioning polymer ahead of a scheduled dewatering run are all examples of dosing that happens in defined windows, not around the clock. A pump built only to run at a constant rate handles this badly: either an operator manually starts and stops it, introducing exactly the kind of unreliable timing a chemical dosing schedule is meant to avoid, or the pump runs continuously because stopping and starting it by hand is inconvenient, and the plant ends up dosing chemical during periods when it isn’t needed.
The Cost of Manual Scheduling
Manual start/stop dosing depends entirely on someone remembering to act at the right time. A shock chlorination that’s meant to start at a specific hour and run for a specific duration is only as reliable as whoever is on shift to press the button, and on unmanned or minimally staffed sites, that reliability drops further. When the workaround is to simply leave the pump running continuously instead, the plant trades scheduling risk for chemical waste, which is its own ongoing cost.
Batch Mode: A Defined Quantity, Delivered on Demand
The Atlanta’s Batch Mode is built for chemical additions defined by total volume rather than an ongoing rate. The operator sets a total quantity to be dosed, from 0.1 to 9,999.9 litres, and a time within which to deliver it, from 1 to 999 minutes, and the pump automatically calculates the minimum and maximum time the dosage can take at its rated flow range, so the entered time has to fall within what the pump can physically achieve. Dosing can be started manually with a single key press or triggered by an external pulse input, and if it’s interrupted partway through, the operator is asked whether to resume the batch in progress or restart it from zero, so a partial dose is never silently treated as a complete one.
Timed Mode: Dosing on a Schedule, With or Without an External Trigger
Timed Mode covers the case where dosing needs to happen on a recurring schedule rather than a single defined batch. The operator sets a quantity to dose, a delay before the first dose, an interval between subsequent doses, and a flow rate, and the pump repeats that pattern automatically. What differs is how the schedule is initiated.
With the trigger input enabled, set to normally open or normally closed, the pump waits for an external signal before dosing the programmed quantity, applying the delay and interval on top of each trigger event. This suits dosing that should only run in response to something else happening in the process, such as a digester cycle or a batch tank filling. With the trigger disabled, the pump runs purely on its internal delay and interval timers, independent of any external signal, which suits dosing on a fixed clock regardless of what else is happening in the plant.
What Happens When an Operator Intervenes Mid-Schedule
Timed Mode’s behaviour when the Pause input is activated depends on which of three modes is configured. Restart Timer stops the dosing and, once the pause is lifted, starts the whole delay-and-interval count again from zero. Freeze Time pauses the countdown exactly where it was and resumes it from that point once the pause is lifted, so no time is lost or gained. Pause Dosing keeps the countdown running in the background but withholds the actual dose until the pause is lifted, so the schedule stays on its original clock even though dosing itself was interrupted. Choosing between these comes down to whether the priority is protecting the schedule’s timing or protecting against a dose being delivered while the process is paused for another reason.
Where This Fits
Batch Mode suits any dosing job defined by a fixed total quantity, a measured polymer addition ahead of a dewatering run, for example. Timed Mode suits recurring chemical additions on a schedule, whether that schedule should be tied to an external process signal or run entirely on its own clock.
Autoflo Technology is the authorised distributor of the Injecta Atlanta series in Malaysia. For help matching Batch or Timed Mode to a specific dosing schedule, contact us at info@autoflotechnology.com.