Control valves with Adaptive Positioning Control (APC)

APC combines two functionally different valves:

• a small, precise control valve for stable operation in the partial load range
• a large control valve for high volume flows and rapid relief

Both valves are not separately, but coordinated and overlappingly controlled.
The control system continuously decides which valve handles which portion.

Result:
stable control over the entire operating range – without switching points or instabilities.

Ein einzelnes Ventil muss gleichzeitig:

• kleine Durchflüsse präzise regeln
• große Durchflüsse schnell und sicher abführen

Das führt zwangsläufig zu Zielkonflikten:

• großes Ventil → schlechte Regelbarkeit im Teillastbereich
• kleines Ventil → zu geringe Kapazität im Störfall

Diese physikalische Grenze lässt sich konstruktiv nicht auflösen – nur umgehen.

APC:

• avoids the "one valve for all" compromise
• operates without abrupt switching points as with Split Range
• enables continuous, stable control
• reduces operation of large valves in the unfavorable partial load range

In practice, this means:

• better control quality
• less oscillation
• lower mechanical load

Yes, in most cases.

Prerequisites:

• Sufficient space for a second valve
• Adjustment of the control strategy
• Integration into existing control system

The modification remains manageable, as the core function (Blow-Off / Anti-Surge) remains unchanged.

APC reduces:

• Continuous operation of large valves in the inefficient partial load range
• Unnecessary actuating movements
• High actuating forces for small control deviations

The large valve operates predominantly in its optimal range,
the small one handles the fine-tuning.

Result:
Less wear, longer maintenance intervals.

Split Range means:

• defined switchover point between two valves
• only one valve active at a time

APC means:

• both valves operate simultaneously
• no switchover points
• continuous distribution of the control variable

This eliminates the typical weakness of Split Range:
instability in the transition range.

Because there is no critical transition.

With Split Range:

• minor error at the switchover point → system jump
• often leads to oscillation or control deviation

With APC:

• smooth transition
• continuous adjustment of both valves

The system remains stable even under changing conditions.

Anti-Surge verlangt gleichzeitig:

• höchste Präzision nahe der Pumpgrenze
• maximale Durchflusskapazität im Notfall

Genau hier versagen klassische Einzelventile.

APC trennt diese Aufgaben:

• kleines Ventil → präzise Regelung nahe Surge
• großes Ventil → schnelle Entlastung

Damit wird erstmals beides gleichzeitig zuverlässig erfüllt.

APC reduces:

• unnecessary blow-off
• operation in inefficient valve positions
• pressure losses due to oversizing

Savings depend heavily on operation, but:

typically measurable effects result from more stable operation and fewer control losses.

APC enhances safety through:

• reliable relief via the large valve
• stable control without oscillation
• reduced likelihood of erroneous actuations

Important:
The safety function (e.g., emergency blow-off) is fully maintained.

Commissioning involves three steps:

1. Basic parameterization of the valves
2. Tuning the control split (small/large)
3. Fine-tuning in actual operation

The focus is on:

• stable transition
• reproducible behavior
• practical settings, not laboratory values

Competitors typically use:

• Single valves
• Boosters
• Split-range logic

APC takes a different approach:

• Functional separation of tasks
• Adaptive, overlapping control
• Seamless control strategy without switching points

The difference is not necessarily in the valve itself,
but in the control concept.