Eductor nozzles for chemical finishing and surface treaments

Storing liquids in tanks is essential for many process industry applications, for example chemicals for finishing and surface treatment applications, as is the need to agitate the contents to avoid separation and sedimentation. Fluids can be recirculated through tanks to achieve separation which helps to optimise chemical action in dip tanks, although the process can be enhanced by the introduction of eductor nozzles.

For many applications eductor nozzles made from brass or stainless steel (as opposed to plastics such as polypropylene) will be the preferred choice, especially if the chemicals are aggressive, or are stored at higher temperatures. However, the new range of PVDF eductors, recently introduced by Bete, are a viable alternative to the more expensive stainless models. PVDF (Kynar) is an incredibly chemically resistant fluoroplastic and has superior heat resistance compared too many other plastics. Furthermore, these new PVDF options are offered at significantly lower cost than stainless steel equivalents.

Eductors are submerged inside the tank and the motive liquid is pumped under pressure though the discharge orifice. The jet of liquid enters the venturi section, entraining additional liquid from the tank and moving it through the venturi. A discharge plume of combined motive and entrained liquid exits the venturi and continues the mixing and agitating action for a substantial distance effectively multiplying the liquid flow. Depending on the model and the operating pressure, the volume of liquid discharged from the eductor will be up to four or five times greater than the volume of motive liquid being pumped. This highly efficient operation reduces energy use and therefore cuts costs.

Eductors can be used effectively wherever chemicals are being stored inside closed tanks yet need to be agitated.

For example: in tanks used for plating, electrocoating and pre-treatment, phosphating, sludge, paint, anodizing, agricultural fertilizers and chemicals, pulp, slurries. There are also options for open tank applications, such as cooking grain, mash and starch, heating, as well as circulating and mixing.