Ethanol pours from the plastic container when the pump continues after the receiving volume is full. The number that matters is delivered volume relative to available container capacity. A preset batch meter measures the transfer, issues a slowdown command near the target, then closes a final shutoff valve and stops the pump at the preset quantity.
Transfer quantity and overflow mechanism
A transfer of up to 1,000 litres becomes an overflow when the volume entering the container exceeds its free capacity. The controller can count delivered liquid, but it cannot infer how much liquid was already in the container. Set the batch target from verified free capacity, not merely from the container's nominal size.
Flow does not stop instantaneously when the electrical stop command changes state. Liquid already moving through the pipe has momentum, a valve takes time to travel closed, and a pump may continue rotating after power removal. The resulting overrun is approximately the flow delivered between the stop decision and actual zero flow. Faster flow, slower valves, longer piping, and pump coast increase that quantity.
| Quantity or limit | Why it matters | Where to read or determine it |
|---|---|---|
Batch range: 0-1,000 litres
|
Defines the required preset and totalizer range | Operator's transfer requirement |
| Available container capacity | Sets the maximum permissible batch after subtracting starting inventory and reserve space | Container marking, calibrated level indication, or measured starting volume |
| Instantaneous flow rate | Determines how quickly the remaining margin is consumed | Flow-meter indication during normal transfer |
| Shutdown overrun | Volume delivered after the final command | Difference between the meter total at the command and the settled final total |
| Slowdown threshold | Creates time for controlled deceleration before final cutoff | Preset controller configuration |
| Valve state and pump state | Confirms that both liquid flow and pumping energy have been removed | Valve feedback, motor contactor or drive status, and zero-flow indication |
Batch-control approaches
| Approach | Measured condition | Strength | Principal limitation |
|---|---|---|---|
| Preset meter with pump stop | Accumulated delivered volume | Directly enters a required quantity in litres | Pump coast and line discharge can produce overrun |
| Preset meter with staged flow and final valve | Accumulated delivered volume | Reduces flow before cutoff, closes the liquid path, and can stop the pump | Requires compatible control outputs, valve selection, and commissioning |
| Container level shutdown | Liquid level at the receiving container | Responds to actual fill level, including starting inventory | Does not independently provide an accurate delivered batch quantity |
| Combined batch and high-level protection | Delivered volume plus actual container level | Separates normal batch control from overflow protection | Adds instrumentation and proof-testing requirements |
Use a preset batch meter with a two-stage sequence: slow the flow as the accumulated total approaches the target, close a final shutoff valve at the target, and interlock the pump off. For consequential ethanol spills, add an independent high-level or high-high-level trip at the receiving container. The batch meter performs normal quantity control; the level trip protects against a wrong preset, unexpected starting inventory, meter failure, or valve failure.
Meter, valve, and pump architecture
The flow meter generates pulses or another quantity signal proportional to delivered liquid. The preset controller integrates that signal into a batch total and compares it with the operator-entered target. One output can request reduced flow near the endpoint; another produces final cutoff. The final cutoff should close the shutoff valve and remove the pump run command through the control circuit.
Place the meter so that its count represents liquid actually delivered to the receiving container. Any bypass, recirculation path, drain, or branch between the meter and destination can make the total differ from container receipt. Mount the final valve so trapped downstream inventory cannot drain uncontrolled into the container after shutdown.
Valve closure protects the liquid boundary; pump shutdown removes energy. Using only the motor stop leaves stored liquid and possible gravity flow uncontrolled. Using only the valve can deadhead a pump if the motor continues running. The control sequence must remove both conditions in an order suitable for the installed pump and piping.
Equipment and installation checks
Ethanol creates a flammable-liquid and vapor hazard. Select the meter, valve, seals, container connections, wiring method, and electrical enclosure for ethanol compatibility and the classified location identified by the site's hazard assessment. Bond and ground the transfer system according to the site's approved design, and route shutdown functions through equipment intended for the required duty.
Before purchasing hardware, record the pump type, normal and maximum flow, discharge pressure, pipe size, supply voltage, control interface, container capacity, desired batch accuracy, and required fail position. Confirm that the meter covers the operating flow range and that its wetted materials match the liquid. Confirm that the valve is rated for the pressure and closes to the safe state when control power is lost.
Check the controller's available outputs against the pump starter, contactor, drive, and valve actuator inputs. Use interposing relays or an engineered interface where voltage, current, isolation, or contact ratings differ. A batch-complete indication is not automatically suitable for directly switching a pump motor or valve load.
Configuration and commissioning procedure
- Define the maximum batch as verified free capacity minus the operating reserve and expected shutdown overrun. Repeat this calculation whenever the starting level or container changes.
- Install the meter in the approved flow orientation and provide the straight piping, strainers, or conditioning specified by its manufacturer. Eliminate bypass paths that would escape measurement.
- Wire the meter signal to the preset controller. Configure engineering units in litres and enter the meter calibration value supplied or established during calibration.
- Connect the slowdown output to the engineered reduced-flow device. This may control a staged valve or another approved means of reducing pump flow; the selected method must suit the pump.
- Connect final cutoff to the shutoff valve and pump run circuit. Configure loss of control power to produce the defined safe state.
- Add permissives so a batch cannot start without a valid container, open transfer route, reset controller, and healthy shutdown chain. Require a deliberate reset after an overflow-protection trip.
- Commission first with a safe test medium and a conservative target where the process design permits it. Run repeated batches at minimum and maximum expected flow, recording command total, settled total, valve response, pump response, and measured receiving quantity.
- Set the slowdown point far enough before the target to make final overrun repeatable. Adjust the commanded cutoff or meter compensation using measured results, then repeat the test after each change.
- Challenge the independent level trip, valve feedback, pump feedback, and emergency stop individually. Verify that no single failed normal-control command allows unattended filling to continue.
Verification and recurring pitfalls
Accept the installation only after the delivered quantity remains below the safe container limit across the operating flow range. Record repeatability as well as average error: an average on target can conceal individual batches that overfill. Test a power interruption and loss of the meter signal, then confirm that the valve and pump reach the defined safe states.
The most common setup error is treating nominal container capacity as available capacity. Other recurring failures include an incorrect pulse scaling value, wrong units, reversed meter flow, air or vapor passing through the meter, valve leakage, an unmeasured bypass, and a shutdown output that indicates completion without interrupting the motor circuit. A changed hose, pipe route, pump setting, or valve can also change endpoint overrun and requires a new test.
Automatic cutoff is not permission to leave an unproven transfer unattended. Establish an operating rule for container identification, starting-volume confirmation, preset review, and shutdown proof before each transfer. Inspect the final valve for leakage and proof-test the independent trip at a documented interval set by the site's risk assessment.
Frequently asked questions
What happens if the container already contains ethanol?
The preset meter still counts only the new delivery. Reduce the batch target by the verified starting volume, operating reserve, and measured shutdown overrun.
What happens if the pump stops but ethanol keeps flowing?
Gravity flow, pump coast, or downstream pipe inventory can continue the transfer. Close a final shutoff valve as part of the batch-complete sequence and verify zero flow after closure.
What happens if the preset meter reaches its target but the valve stays open?
Stop operation if the shutdown chain, valve feedback, or delivered-volume test fails, or if any component lacks the required ethanol, pressure, or hazardous-location rating. Escalate to the equipment manufacturers' official technical support and the site's qualified electrical and process-safety personnel with the wiring diagram, meter scaling, flow data, and recorded shutdown test results.