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Nozzle Maintenance


Spray Nozzle Maintenance
Extending Spray Nozzle Life


Selecting the right nozzle for each wash stage is just the first step toward optimizing your spray system. The following tactics will help you get more service life from your nozzles.

1. Incorporate nozzle inspection into your regular maintenance program
Damaged spray nozzles waste water and chemicals, decrease cleaning coverage of the vehicles and increase workload on your pumps. With thousands of dollars of profits at stake, you’ll want to regularly monitor your spraying system to reveal potential problems. Some nozzle problems like corrosion or caking, are easy to detect with a visual inspection, but a worn nozzle, the most common problem for a car wash, is almost impossible to detect with the human eye.

Watch for these clues to indicate spray nozzle problems:

Change in pump performance
If you have a positive displacement pump, check the pressure gauge for a drop in system pressure. If there is a drop in pressure, the flow rate will remain constant, but spray velocity and impact will lessen. You may not be wasting water, but the quality of your wash will suffer. Some operators will adjust the unloader valve and use it as a regulator to increase pressure, but this can create high-pressure spikes and damage the pump.

Deterioration of spray pattern
Inspect the spray pattern for uniformity. When nozzles are damaged, worn or clogged the spray pattern is destroyed. Streaks develop and the spray will be heavier or lighter throughout the pattern. The result is inadequate or inconsistent coverage of the vehicle. Customers will experience uneven cleaning or drying, so you’ll want to make sure your nozzles are replaced before reaching this point. Customer satisfaction and retention depends on it.

Increased chemical consumption
As the nozzles wear and pressure/impact decreases, some operators increase the concentration of the detergent – a much more costly solution than replacing nozzles.

Flow rate change
If you have a centrifugal pump, an increased flow rate indicates nozzle wear. System pressure will remain the same, enabling you to retain some quality in your wash, but your system will be highly inefficient, wasting costly water and chemicals.

2. Decrease spraying pressure
Where circumstances permit, decreasing the pressure will slow the liquid velocity through the orifice and reduce the wear and corrosion rate. You can take advantage of this tactic in the presoak stage where low pressure, small capacity nozzles are very effective because they provide streak free, full coverage. During presoak, it’s not the volume or spray impact that’s critical – it’s where you place the water and chemical.

3. Use care when cleaning spray nozzles
Cleaning nozzles can often restore a defective spray, but it should be done with materials that are much softer than the nozzle orifice. Use toothbrushes, toothpicks or even compressed air. Never use wire brushes, pocket knives, or welder’s tip cleaning rasps. It is easy to damage the critical orifice shape (or size) and end up with distorted spray patterns or excess flow. If you are faced with a stubborn clogging problem, soak the orifice in a non-corrosive cleaning chemical to soften or dissolve the substance.

4. Reduce the quantity of abrasive particles or the concentration of corrosive chemicals
In some stages, you can reduce the amount of abrasive particles in the liquid to reduce wear effects. For example, use recycled water at the start of the car wash, and as the wash progresses use less recycled water until the final rinse where only fresh water is used. Not only does this provide a better quality wash for your customers, but it also reduces the wear on nozzles at the final rinse stage. In stages where chemicals are used, the corrosive activity of a solution may be reduced by using different concentrations or temperatures, depending on the chemicals involved.

5. Add line strainers or use spray nozzles with built-in strainers
When using fresh or recycled water, orifice deterioration and clogging are typical problems. Strainers or spray nozzles with built-in strainers are highly recommended in the presoak cycle. Line strainers not only extend the life of the nozzle but the pump also. The strainer’s screen traps the dirt or unwanted material and it should be made of stainless steel for strength and corrosion resistance. The screen is critical to the operation of the strainer and an extra screen should be kept on hand for each strainer installed.

Common Causes of Spray Nozzle Problems

Erosion/Wear Life
Erosion is the single biggest cause of nozzle problems in a car wash operation. Gradual abrasion of material from the spray nozzle orifice and internal flow passages cause them to enlarge and/or become distorted. As a result, flow usually increases, pressure may decrease, the spray pattern becomes irregular and liquid drops become larger. Spray pressure, fluid abrasiveness, nozzle orifice size and chemical compatibility are just a few of the factors that play a role in a nozzle’s wear life. You can minimize how quickly your nozzles wear by selecting materials of construction with a higher resistance ratio.

Clogging
Unwanted solid particles can block the inside of the orifice. Flow is restricted and spray pattern uniformity is disturbed. This is often a problem when re-circulated water is insufficiently filtrated

Accidental Damage
Damage can occur if a spray nozzle is dropped or scratched during installation, operation or cleaning. This a common occurrence in self-service car washes, since many customers often let spray wands fall onto or scrape against the concrete floor of the bay

Corrosion
Spray nozzle material can also break down due to the chemical qualities of the sprayed material or the environment. The effect is similar to that caused by erosion and wear, with possible additional damage to the outside surfaces of the spray nozzle.

Caking
Build-up of material on the inside on the outer edges or near the orifice is caused by liquid evaporation. A layer of dried solids remains and obstructs the orifice or internal flow passages.

Improper Assembly
Some spray nozzles require careful re-assembly after cleaning so that internal components such as gaskets, O-rings and vanes are properly aligned. Improper positioning or even over-tightening of nozzle caps can strip threads and can cause leaking and inefficient spray performance

A Simple Way to Detect a Flow Rate Change

Date Published: 21 October 2016
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