Pressure and Vacuum in a Windshield Repair Resin Injector

Question:

Answer:

1. The cylinder is screwed down and adjusted until the end seal creates an airtight seal against the glass.
2. The cylinder is filled with resin until it is above the end seal.
3. The plunger is screwed into the cylinder until the tip of the plunger enters the top of the end seal. If using a spring type injector the plunger is set to the vacuum position until the plunger is screwed down until it stops, then set to the pressure position, which allows the tip of the plunger to enter the top of the end seal.
4. The end seal is now a sealed vessel, so when pressure is applied, either by screwing the screw type plunger down, or by applying thumb pressure to a spring type injector, the resin in the end seal pressurizes, forcing the resin into the airspace in the glass.
5. Unscrewing a screw type plunger, or pulling up on a spring type injector creates a vacuum in the end seal that pulls air from the airspace in the glass.
6. When the tip of the plunger is raised above the top of the end seal, the vacuum action stops as the air pulled from the glass is released into the upper cylinder of the injector.
7. As the air is released, the resin above the seal once again fills the end seal, so that as the plunger is lowered into the end seal again the pressure cycle is once again initiated.
8. As long as the level of resin stays above the end seal the alternating pressure and vacuum cycles can be repeated until all the air in the glass has been replaced with resin.