catalogue-thumb

Nozzles for Pre-treatment applications

Engineering Considerations - Chemical compatibility

Pre-treatment tunnels are a series of stations spraying a variety of chemicals. Some chemicals like the phosphates used for anti-rust conversion coating are specifically used because they react with metals. The whole point of the phosphate spray is to cause a reaction on the surface of the metal being sprayed to form a corrosion-resistant film.  Spraying phosphates through metal nozzles is thus problematic. There are metals that are resistant to the actions of phosphate but they tend to be more expensive and as pre-treatment plants run at temperatures below 100 degrees, plastics such as glass filled poly-propolyene tend to be the more cost effective choice of material.  

 

Poly-propelyene, PVC, CPVC or PVDF quick change system

The Uni-Spray quick change system is manufactured in glass filled poly-propelyene, PVC, CPVC pr PVDF. These materials give excellent chemical resistance, are hard wearing and relatively inexpensive. This makes them all ideal for use in pre-treatment tunnels. Indeed the Uni-Spray system is regarded as the market leading system worldwide in this niche segment. A table of their relative properties is given below.

 

 

 

 

 

Material

 

 

 

 


 

 

 

 

Temp rating

 

 

 

 


 

 

 

 

Chemical compatibility

 

 

 

 


 

 

 

 

Corrosion resistance

 

 

 

 


 

 

 

 

Strength

 

 

 

 


 

 

 

 

Cost

 

 

 

 


 

 

 

 

PVC

 

 

 

 


 

 

 

 

60oC

 

 

 

 


 

 

 

 

High

 

 

 

 


 

 

 

 

Good

 

 

 

 


 

 

 

 

Low

 

 

 

 


 

 

 

 

Low

 

 

 

 


 

 

 

 

CPVC

 

 

 

 


 

 

 

 

100oC

 

 

 

 


 

 

 

 

High

 

 

 

 


 

 

 

 

Good

 

 

 

 


 

 

 

 

Medium

 

 

 

 


 

 

 

 

Medium

 

 

 

 


 

 

 

 

Glass filled poly-propeleyne

 

 

 

 


 

 

 

 

70oC

 

 

 

 


 

 

 

 

High

 

 

 

 


 

 

 

 

Good

 

 

 

 


 

 

 

 

High

 

 

 

 


 

 

 

 

Medium

 

 

 

 


 

 

 

 

PVDF

 

 

 

 


 

 

 

 

120oC

 

 

 

 


 

 

 

 

High

 

 

 

 


 

 

 

 

Excellent

 

 

 

 


 

 

 

 

High

 

 

 

 


 

 

 

 

High

 

 

 

 


 



Spray Tunnel Engineering Considerations

UniSpray System Parts

Pre-treatment nozzle selection table