Process and Control

Our process and control include complete engineering and circuit diagram design and more.

The sera program of controls includes a number of standadised basic controls for economic integration of sera metering pumps into automatic processes.

Depending on the type of dosing we differentiate between three groups:

  • Batch dosing
  • Proportional dosing
  • Dosing in a control circuit



Our team is there for you!

Do you have any questions about this item or need more information?

Contact us!

Performance characteristics

  • Complete engineering and circuit diagram design
  • Expert switch cabinet assembly
  • Fully mounted dosing unit to requirements

1. Batch dosing with pre-selection pulse counter

Batch dosing with pre-selection pulse counter
The required number of pump strokes per batch is set with an electronical pre-selector. Once a start pulse is given, the pump begins to operate.

At each pump stroke the stroke frequency initiator on the pump subtracts one stroke at the pre-selection counter. When the pre-selected value has been reached, the pump switches off automatically and the next charge can be started.


2. Proportional dosing

Proportional dosing via pulse signals
Proportional dosing with the dosing pump of the C-series depends on the pulses of a contact water meter. The integrated electronics of the pump convert the pulses into dosing strokes, providing the facility of pulse partitioning or pulse multiplication.

Proportional dosing via analogue signals
Proportional dosing with the metering pump of the C-series depends on the range of analogue input signals 0/4...20 mA from a flow meter.
The electronics integrated in the pump convert the analogue signals proportionally into the respective stroke frequency.

Proportional control with frequency converter operation:

EA frequency converter within the control mechanism converts the input signal 0/4...20 mA directly into the proportional output frequency which is passed on to the three-phase motor of the pump. Changes in the frequency effect a relative change in the motor speed and the corresponding pump strokes. Consequently, the flow capacity of the pump is controlled by the stroke frequency at even stroke lengths.

Proportional control with electrical actuator:

An electronic positioning controller within the control mechanism compares the command signal with the position of the actuator received by a message from the positioning potentiometer.

If a discrepancy occurs, the actuator and so the through-put rate of the pump are adjusted via the stroke length until the actual and the set quantities of the dosage tally.

3. Dosing in a control circuit

Proportional pulse length controller
The pulse length controller is a switching controller which operates by switching ON or OFF.
The relationship between switch-ON and switch-OFF time and of run to pause of the dosing pump changes proportional to the discrepancy between the settings.
Since the dosing pump can only be switched ON or OFF, a standard pump without stroke setting facility and without controllable motor can be installed.

Three-point step controller
For process controlled systems with higher control performance a continuous dosing and flow capacity adjustment is necessary.
The three-point step controller which controls the stroke initiator of the metering pump fulfils this requirement to an optimum degree. The metering pump is in continuous operation. When a discrepancy from the setting occurs, the controller emits ON or OFF pulses in steps to the initiator until the expected value and the actual value tally.

Continuous controller
The continuous controller is designed for regulating higher capacities.
Its output is an analogue signal which can accept all intermediate values between 0 and 100% continuously. The output of the continuous controller goes directly to a frequency converter which adjusts the flow capacity of the reset pump continuously by changing the motor speed until the discrepancy equals zero.

Proportional pulse frequency controller
The pulse frequency controller shows the output rate only as a pulse signal. The frequency of the pulse signal changes in relation to the setting discrepancy. This controller allows the installation of a dosing pump of the C-series. The integrated electronics convert the pulse signal into dosing strokes.