Meaning
Loss of fluid pressure that occurs as a viscous material moves through hoses and nozzle orifices during active dispensing. A dynamic pressure drop increases as the material flow rate or viscosity rises, demanding higher pumping force to maintain a steady output. This metric is a key factor in sizing pneumatic and hydraulic actuators used in adhesive delivery.
Flow Characteristic
Frictional resistance between the moving fluid and the internal tube walls causes energy losses that appear as a reduction in pressure along the flow path. This dynamic pressure drop occurs and intensifies as the internal diameter of the tubing narrows or as the flow path turns sharply. Non-Newtonian fluids can show variable resistance since their viscosity changes under high shear conditions within the nozzle.
The total resistance is determined by both the fluid density and the velocity profile through the channels.
System Implication
Excessively high pressure drops can stall feed pumps or rupture flexible delivery hoses. This condition disrupts production.
Operational Variable
Adjusting the internal diameter of the transport hoses and minimizing the length of the flow path are effective methods to manage fluid friction. Heat can also be applied to the material lines to lower the fluid viscosity and reduce the force needed to move the material. Selecting a nozzle with a shorter land length reduces the overall flow restriction at the terminal point of the dispensing cycle.
