1、 Cause analysis of surface corrosion of screw pump rotor

The feed medium of the vacuum pump contains sulfur dioxide and water. Sulfur dioxide combines with water to form sulfurous acid. Sulfurous acid has a corrosive effect on metals. In order to prevent corrosion of rotor and pump cavity, Teflon layer is coated on the surface of rotor and pump cavity. Corrosion of rotor and pump chamber indicates that the layer is damaged and sulfite has corroded to the pump chamber.

2、 Failure analysis of Teflon layer in rotor and pump chamber

There may be three reasons for the surface layer damage of rotor and pump chamber:

First, solid particles enter the pump cavity, which causes coating damage.

Second, chemicals form colloid on the pump cavity and rotor, which carbonizes and hardens and destroys the coating of rotor and pump cavity.

Third, other reasons.

1. Failure analysis of solid particles

Check the pump inlet equipment and pipeline, and no free moving solid particles such as metal fragments and iron chips are found.

2. Analysis of colloidal carbon deposition failure

Fig. 1 is a picture of the attachment on the inner wall of the pump inlet pipe. The substance is dark brown. After analysis, it contains iron, carbon and oxygen. It is a polymeric substance such as butadiene and sulfolane, which is bonded to the inner wall of the pipe. If the substance adheres to the pump cavity and rotor surface, it is easy to carbonize and harden, thus damaging the rotor surface layer.