Fixed vs. Variable Flow

High pressure coolant systems may provide a constant flow rate (Fixed Flow) or a variable flow rate. Fixed flow pumps rotate at a constant speed and the coolant pressure results from the size of the tool being used. Fixed flow systems use a regulating valve to set the maximum system pressure. When running small tools with a Fixed flow system, excess coolant is bypassed through the pressure regulating valve.

Variable Flow systems adjust the flow rate as required to maintain a constant pressure. Larger or multiple tools result in higher flow rates. Smaller tools result in lower flow rates.

The pros and cons of the two types of systems are shown below.

Fixed Flow

Variable Flow

Pros

  • Low Cost
  • Ease of Installation
  • Ease of troubleshooting

Pros

  • Adaptive, system pumps only as much as the process requires
  • Maintains optimum pressure
  • Reduces heat build-up in coolant
  • Simple to automate for selectable pressures (i.e. 300, 1000, 2000psi)

Cons

  • Fixed flow can be either too much or too little
  • Can consume unnecessary energy
  • May generate excess heat due to coolant bypass.

Cons

  • Higher Purchase Cost
  • Specialized knowledge / Programming required for Installation
  • Skill for troubleshooting / support