The purpose of flushing is to avoid the accumulation of impurities, prevent the formation of airbags, adhere to the mechanical seal of the fire pump, and improve smoothness. When the temperature of the flushing liquid is low, it also has the cooling effect of multi-stage pump mechanical seals. Now let's introduce the flushing method and characteristics of mechanical seals for pumps.

Mechanical seals for pumps

1、 Internal erosion

1. Positive erosion

(1) Feature: The sealed medium used in the homework host is introduced into the sealing chamber through the pipeline from the outlet end of the pump's Naichi mechanical seal.

(2) Usage: Used for cleaning fluids, with p1 slightly larger than p. When the temperature is high or there are impurities, coolers, filters, etc. can be installed on the pipeline

2. Backwash brush

(1) Feature: The sealed medium of the homework host is introduced into the sealing chamber from the outlet end of the pump, flushed and flows back to the pump inlet through the pipeline.

(2) Usage: Used for cleaning fluids, and P enters

3. Full scouring

(1) Feature: The sealed medium of the homework host is introduced into the sealing chamber through the pipeline from the outlet end of the pump, flushed, and then flows back to the pump inlet through the pipeline.

(2) Usage: The cooling effect is superior to the first two methods, used for cleaning fluids, and when p1 is close to the inlet and outlet of p.

2、 External erosion

Feature: Introduce cleaning fluid compatible with the sealed medium into the sealing chamber for flushing.

Usage: The external flushing fluid pressure should be 0.05-0.1MPa higher than the sealed medium, suitable for situations where the medium is high temperature or solid particles. The flow rate of the flushing fluid should ensure the removal of heat and meet the flushing requirements without causing erosion to the sealing components. For this purpose, it is necessary to control the pressure of the sealed chamber and the flow rate of the flushing fluid. Typically, the flow rate of the cleaning flushing fluid should be less than 5m/s; The slurry liquid rich in particles must be less than 3m/s. In order to achieve the above flow velocity value, the difference between the flushing liquid and the sealing chamber pressure should be less than 0.5MPa, usually 0.05-0.1MPa. For double end mechanical seals, 0.1-0.2MPa can be taken. The direction of the flushing liquid entering and exiting the sealing chamber should be set near the sealing end face and close to the dynamic ring side. In order to avoid the graphite ring being eroded or causing temperature difference deformation due to uneven cooling, as well as impurity accumulation and coking, tangential introduction or multi-point flushing can be used When necessary, the flushing fluid can be hot water or steam.