Troubleshooting

A quick visual inspection may be all that’s required to troubleshoot spray performance problems. Here are some of the most common ones.

Corrosion
Nozzles that degrade due to chemical reactions between the nozzle material and chemicals in the process need to be replaced. If the wear occurs more quickly than expected, check with the chemical supplier or system designer to discuss alternative nozzle material options.

Temperature
Nozzles subjected to temperatures greater than recommended for the material of construction can be physically damaged or melted.

Erosion/Wear
As fluid passes through the orifice and internal passages of the nozzle, the critical surfaces can become worn, leading to poor quality spray.

Clogging
Many chemical compounds have particles which are larger than the maximum free passage of the nozzle, resulting in clogging.

Caking
Another form of clogging. Chemicals slowly build up on the surfaces of a nozzle and restrict the flow, eventually plugging the nozzle orifice or internal passages.

Mechanical Damage
Cross threading, over tightening, or stripping the hex are ways that a spray nozzle can become mechanically damaged. If it’s difficult to remove a damaged nozzle for inspection, it will be much more difficult when the nozzle has been in service and needs replacing.

Incorrect Assembly
Care must be taken when reassembling a nozzle. Internal components must be installed correctly or the nozzle will not perform as intended.

Low Flow Rate
If the flow rate is lower than expected, the nozzle performance will suffer. Ensure there are no blockages in the piping system between the pump and the nozzles, and that the pump has the capacity for the system. Pressures should be measure directly at the nozzle for the best accuracy.

Flow Rate
Flow rate can be measured by connecting a flow meter in series with the nozzle, or by collecting the discharge from the nozzle in a receptacle of known volume over a measured period of time. If the flow rate is higher than the nozzle specifications, it’s possible that the orifice has worn away from corrosion or erosion. If the flow rate is lower than specified, the nozzle orifice may be clogged or caked. These problems are often accompanied by a change in pattern or distribution.

Pressure
A decrease in system pressure could indicate excessive nozzle wear. An increase in system pressure could indicate that some nozzles have become clogged. It’s important that accurate pressure readings are taken at the nozzle rather than upstream or at the pump. Every system experiences a degree of pressure losses in the piping systems.

Distribution
All nozzles have a specified spray pattern, distribution, and spray angle. If performance is not as expected, it could indicate that the nozzles are worn or plugged.

Finished Product Quality
When spray nozzles are in environments that are impossible to monitor in real time, such as spray booths, a poor quality finish may indicate a closer inspection is required.

Alternative Materials
Some materials are better suited than others for certain applications. The incorrect nozzle material can wear very quickly due to corrosion or erosion, given the right combination of chemicals, temperature, and pressure. In this case, check with the chemical suppler or system designer to determine the best possible material for your application.

Clean Nozzles Regularly
Regular nozzle inspection will help identify nozzles that need cleaning to prevent problems. Nozzles should only be cleaned with soft tools or with chemicals approved for the type of nozzle material. Orifice edges and many surfaces can be easily damaged, which affects nozzle performance. New spray nozzles will always perform better than a cleaned nozzle and could save the cost of lost productivity or poor product quality.

Change Nozzle Type or Size
If the same problems keep recurring, a change in the style of nozzle may be required.

Decrease Operating Pressure or Temperature
Higher operating pressures can result in higher mechanical wear. With plastic nozzles, temperature can be an important factor in lower nozzle life expectancy. Check with chemical suppliers and system engineers to determine whether there is room for adjustment in the process conditions.

Reduce the amount of Abrasives in the System
Nozzles will wear out prematurely as a result of excessive abrasion. Without proper filtration, a system may have unexpected abrasives in the fluids. These abrasives can lead to excessive wear in the spray nozzles, as well as in piping systems, pumps, and other mechanical equipment in the system.

In troubleshooting eductor systems, it’s critical to know the pressure drop across the eductor. To determine this, the pressure at the eductor entrance is required, which requires a pressure gauge near the eductor. If this pressure is too low, the velocity at the nozzle orifice will be too low and the eductor won’t provide the expected mixing/agitation.

The main causes for low pressure are:

• Undersized or malfunctioning pump
• Undersized or poorly routed piping
• Blockages in the piping prior to the eductors (plugged filters)
• Leaks in the piping or elsewhere in the system.

Other reasons why an eductor system will underperform are:

• Poor eductor layout (position, orientation )
• Insufficient quantity of eductors
• Damaged eductors (broken or corroded)