Eductors are used in dip tanks to circulate the liquid
The eductors are used to cause a flow of the liquid contained in the dip tank - this effect is called agitation, and is necessary to keep solids in suspension. Agitation is required to make sure that the liquid is well circulated and completely covers the product
Tanks are emptied 1-2 times a year and some tanks have acid wash applied
The dip tanks used in the car industry are usually between two and three cars in length.
Each tank will have up to thirty eductors fitter depending on tank size. The eductors are fitted into the tank on a ladder pattern as shown in the diagram.
The most common size of eductor used in the car industry is 3/4 inch BB300
This nozzle gives a liquid turnover of 3:1. This means that the volume of liquid drawn in is about 3 times the volume of e liquid pumped through the nozzle orifice.
Most existing eductors in tanks are stainless steel which are screwed into welded sockets
Most new eductors are made from Glass Filled Polypropylene
They are very efficient for use in the "Pre-Treatment" process that many products go through before paint dipping application. "Pre-Treatment" ensures that product is clean and often applies protective coatings such as phosphate, chromate or a paint primer.
The eductors are hardly ever changed
The main reason for changing an eductor will be if the car body falls off the track and damages the eductors as it is dragged through the dip tank
Dip tanks will be cleaned using a weak acid wash down, approximately twice a year