Real Time Process Control with FPC: Fluid Pressure Control

Patented Pressure Regulating System for Fluid Dispensing Systems for FPC Technology

Real Time Process Control (FPC) is a breakthrough in uniform fluid dispensing. FPC ensures a constant supply of fluid is always available to the pump regardless of reservoir size or fluid level.

Common issues encountered when dispensing fluids are illustrated in the graphs below. Natural variation occurs when constant air pressure is applied to a syringe (graph below left). The variations primarily originate with syringe fluid level and stiction (static friction) of the stopper and syringe wall. When FPC is applied, results improve (graph below right).

Fluid Pressure Control Dispensing
Dispensed Weight Testing with Half Full Fluid Reservoir and an Auger-based Pump.

The Problem

Why do dispense results change over the course of a day and from day-to-day even if material is fed from the same reservoir? Dispense pumps are by nature very consistent in their operation and can cycle at extremely high levels of repeatability, so what's the problem?

Factors Affecting Uniform Dispensing
Factors Affecting Uniform Dispensing.

The above factors result in varied output and would commonly be compensated by an operator making adjustments to the program or reservoir pressure.

Current Feed Mechanisms = Inconsistent Results even with constant reservoir pressure

  • Programmed or adjusted pressure is applied to the reservoir. Pressure remains constant regardless of other factors present (fluid variation, reservoir level, stiction, etc.)
  • Operators spend valuable setup time guessing which software parameters need to be adjusted and how much to adjust pressure because intial dispense results are unpredictable.

Other compensation methods include:

  • Weight scale - repeated use wastes fluid, impacts throughput time, and can be costly
  • Vision calibration - only viable for single dots, impacts throughput time, and does not accurately adjust for larger volumes.

The Solution - Consistent Dispense Results with Real Time Process Control (FPC) regardless of Reservoir Level

FPC provides a consistent feed of fluid to the dispensing pump regardless of reservoir fluid level or stopper stiction.  FPC monitors the pressure of fluid entering the dispense pump and makes adjustments to the reservoir feed pressure, resulting in a consistent feed to the dispense pump.

The chart below shows how inlet pressure to the pump can vary when constant pressure is applied. (1 min between tests)

How inlet pressure to the pump can vary when constant pressure is applied.

The chart below illustrates how the Real Time Process Control system maintains the inlet pressure by adjusting the reservoir pressure.

How FPC maintains the inlet pressure by adjusting the reservoir pressure
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When the feed pressure is consistent, dots will be uniform over the life of the reservoir.  Line or gasketing patterns will dispense in a uniform width and encapsulation processes will dispense a repeatable weight.

FPC applies to nearly all types of dispensing pumps based on a material feed or time and pressure:

  • Auger pumps
  • Jetting Valves
  • Pinch Tubes
  • Needle Valves
  • Even simple time pressure systems

FPC is available in all GPD Global dispense platforms.  An offline control system is available to interface with your existing dispense pump.  Contact GPD Global for details.