Nozzles are precision parts and if they get corroded, even in a small way, they're not going to perform well. This will affect spray performance.
The solution: Material selection is very important. The environment must be assessed along with the corrosives and the correct material must then be selected for the spray nozzle.
Corrosion occurs at different rates and temperatures, therefore the temperature of the environment must also be assessed to ensure the most suitable material is chosen. The material must be able to resist corrosion at that specific temperature.
If the environment is too hot for the spray nozzle, this can cause some deformations within the spray nozzle; the smallest of deformations can cause big problems with the spray because, as mentioned before, spray nozzles are precision components.
The solution: Material selection is once again, very important.
If you are spraying in a hot environment, it is also a wet environment. When looking at compatibility charts, it is essential to be careful and look at the ones from the spray nozzle manufacturer rather than general material temperature compatibility charts. The ones from the spray nozzle manufacturer will often be quite a lot lower because they’re geared towards actual spray nozzles rather than other more general components.
Another way of overcoming this problem is through heat shielding. Various heat shielding solutions can be looked at to protect the nozzle from the extremes of temperature.
This can either be caused by the fluid being sprayed through the nozzle itself or by external factors within the environment such as particulates within a gas flow.
The solution: Again, material selection is key.
In a high pressure/wear environment, harder and more robust materials for nozzles must be selected otherwise regular replacements will be required.
Whilst material selection reduces this, it won’t completely eliminate it. All nozzles are a wear part and the real solution to this is not only selecting the correct material, but also regular inspection of those nozzles and providing replacements when needed. Even with the hardest materials, they're still going to wear eventually.
This is where particulates within a liquid build up within the nozzle and clog the orifice. This will obviously cause poor spraying.
The solution: Source better filtration and use clog resistant nozzles such as spiral nozzles or our MP nozzles that have naturally clog resistant designs.
Caking is build up around the nozzle. It is not clogging internally but the liquid is building up a material externally.
The solution to this is anti-bearding or anti-clogging designs that are naturally smooth and don’t have places for that matter to form.
Low adhesive materials such as PTFE can also be used because it is a slippery material that will not present any opportunity for product build up.
Also, regular inspection is very important because in many environments, caking cannot be totally prevented. But by regularly inspecting, removing and replacing the nozzles, caking will be kept to a minimum.
Mechanical damage often occurs from the overtightening of threads and nozzles generally will have tapered threads. Tapered threads don't like to be undone and redone up lots and lots of times because they're not designed for that.
They're designed to form a fluid seal and by overtightening them and taking them on and off regularly, those threads can become damaged which can lead to a leak.
The other big cause of mechanical damage is incorrect cleaning methods.
If people are sticking things in the orifice to clean them out or using wire brushes etc, the orifice of the nozzle can easily become damaged.
The solution: Clean them correctly and treat them with care. Nozzles are delicate components.
The fluid supply system cannot maintain the correct pressure that the nozzle needs to see to get the correct flow rate or the correct drop size. The back pressure from the nozzle will drop accordingly and will be spraying at a much lower pressure.
A lower flow rate and bigger drop size may cause all sorts of problems within the system, depending what it is.
The solution: Conduct pressure drop calculations and size the pump correctly to account for them.
This is slightly different to poor fluid pressure.
A pump that can deliver the correct maximum pressure for example, may not have enough capacity to deliver the correct flow rate. The spray will then generate a back pressure much, much lower which would result in similar types of problem to having a pump that cannot deliver the correct pressure. It will end up spraying poorly and may splutter.
The solution: Conduct pressure drop calculations and size the pump correctly. The pressure and flow rate of the pump are not the same as the pressure that the nozzle sees. Gravity pressure losses and frictional pressure losses must be conducted.
It is what the nozzle actually sees at the end of the pipe system that is important.
Perhaps the nozzles are getting bashed and misaligned or threaded in incorrectly. This can cause the spray to go in the wrong direction.
The solution: Align them properly. If the nozzles become unaligned for no obvious reason, adjustable nozzle holders allow an easy realignment of the nozzle without having to toil with the pipework. Dove tale nozzles are also a suitable solution; rather than having a thread, these nozzles have a dove tail connection and will slot in the correct orientation in a spray bar for example.
Those are 9 common causes of spray problems with spray nozzles and the potential solutions. Please don’t hesitate to get in touch with one of our friendly spray nozzle experts for any further advice and solutions.
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