Air Bubbles And How To Prevent Them For An Error-Free Work Process.
A common occurrence that may appear in dispensing fluids is air bubbles.
Air bubbles can occur in many different ways. They can form naturally when air is trapped between the folds of high viscosity fluid whilst dispensing. Forceful or excessive air pressure applied to the dispensing system, syringe or cartridge can also create air bubbles. Sometimes air can be trapped in the delivery pipes of fluid tanks to the dispensing systems. Leaky equipment and accessories like pipes, pumps or valves can also be one of the main reasons for air bubbles in fluid materials. In short, there are many reasons why there could be air bubbles in fluid materials, but how will air bubbles affect fluid bonding and adhesiveness?
Air bubbles not only cause a defect in appearances, adhesiveness to the bonding materials but also impair physical properties. It can also result in dispensing defects and inconsistencies which may hinder product quality and fluid wastage.
Here are some ways to prevent air bubbles from forming
- Store syringe, cartridges, tanks, barrels, etc in an upright position.
- Never leave them lying on their side.
- When dispensing from a syringe, it is preferable to use pressure not exceeding 60 psi.
- For a two-part fluid mixture, consider a Dual Components Meter-Mix Dispensing Systems.
- Mixed and dispensed without creating air bubbles. In fact, some of these systems come with degassing features.
How to eliminate air bubbles
- Vacuum degassing (Chamber):
- Pour fluid material in a large container that is at least five times larger in volume. The amount of vacuum pressure to use depends on the material. However, it is also possible that too much time in the chamber will have the opposite effect and affect fluid material properties.
- Vacuum degassing (in tanks with Agitator)
- Degassing in pressure tanks can be more effective if combined with an agitator.
- Fluid Centrifugal Deaerator
- This works very well by "moving" the air bubbles in the material to one end. The time needed for this process depends on material viscosity.
- Store bottles and syringe upright.
- This method can be effective if the material is not viscous as the air bubbles can float up to the piston end of the syringe or escape through the surface of fluid material in a bottle.