Give it some regular TLC
Spray nozzles, like other precision components, will wear over time with use.
This wear can cause nozzles to spray over their capacity which can be extremely costly. Even nozzles that are slightly worn (10 to 15 percent) can cost you tens of thousands of dollars annually. Nozzle wear can cause product quality issues and increase water, chemical and power consumption.
Here are a few important guidelines to help with nozzle maintenance.
DETECTING NOZZLE WEAR
Check the flow rate. Monitor flow meter readings to detect increases or measure the spray from the nozzle for a given period at a specific pressure. Then compare these readings to the flow rates listed in the manufacturer›s catalog or compare them to flow rate readings from new, unused nozzles.
Visually check the spray pattern. Wear will cause spray patterns to become streaky. Look for the heavier areas which may be visible in the center and the edges of the pattern. If necessary, measure the spray angle with a protractor to see if wear may be occurring.
Check the spray coverage. Nozzle wear and nozzle alignment can cause issues for uniform spray coverage—check both when coverage begins to be an issue.
Check the spray pressure and volume. Nozzle wear can be reflected in the spray pressure and the spray volume. With centrifugal pumps, monitor for increases in liquid volume sprayed. With positive displacement pumps, monitor for pressure decreases.
Watch for larger drop sizes. Drop size increases cannot be visually detected in most applications. Examine the application results for changes. Also, it’s important to note that increases in flow rate or decreases in spraying pressure will impact drop size.
BASIC REGULAR MAINTENANCE
Clean nozzles carefully. Nozzle orifices damage easily. Be mindful of the importance of size and integrity of the orifices when cleaning your nozzles.
Use the right materials. Clean your nozzles with items softer than the surface of the orifice. Plastic bristle brushes and/or wooden and plastic knives are ideal. DO NOT use wire brushes, pocket knives, welder›s tip cleaning rasps or anything harder than the surface of the orifice.
Don’t force clean. Rigorous cleaning may do more harm than good. If cleaning is difficult or potentially damaging, consider soaking the nozzles in a mild solvent to loosen debris. Be sure the nozzle material can withstand the solvent.
WHEN TO REPLACE SPRAY NOZZLES?
Do the math. Sprayed solutions have associated costs. Calculate how much your worn nozzles are costing you in wasted water and chemicals versus replacing them.
Consider the cost. Product quality has a high value. Determine what the deteriorating quality on your finished product or application will cost. These costs could include scrap, product rework and customer service problems.
Set a trigger point. Nozzle wear has its limits. Identify a specific flow rate increase or pressure decrease that signals it is time to replace your nozzles.
EXTEND NOZZLE SERVICE LIFE
Use strainers. Line strainers or nozzles with builtin strainers are recommended. The screen mesh will trap larger particles and prevent debris from entering the nozzle orifice or vane.
Consider nozzle material. Materials with harder surfaces generally provide longer wear life. Make sure to choose the right material for your application.
Decrease spraying pressure. Higher pressures can speed up nozzle wear. If possible, decrease the liquid velocity through the orifice. This may help reduce wear and corrosion.
Source: Spraying Systems Co., Wheaton, Illinois 60187-7901.