AIR QUALITY IS KEY
Compressed air – the driving force for paint atomization
… but also the cause of bad paint jobs.
100% technically clean air is the basis to ensure flawless tool function.
To ensure perfect finishes, compressed air for spray guns must meet the following criteria
⊕Sufficient, even pressure
⊕Adequate air volume
⊕The highest amount of purity
must be available at the air connection of the delivery hose to the compressed air tool. In case one of the above criteria is not fulfilled finish problems may occur that a dissatisfied customer will not be willing to pay for.
Compressed air is also required for material delivery in pressure tanks or pumps, gun washers and other air tools. In this case, the same criteria apply the same as with paint atomization.
Problems affect the paint job with dust, water and silicone (fish eyes) and shorten the function and lifetime of pumps and pneumatic tools. Have your compressed air quality checked. The enclosed Troubleshooting Chart is a simple aid to detect problems and their causes and provide corresponding remedies to provide finishes the customer will be happy to pay for.
Air leaks are very expensive
Even small, permanent leaks cause considerable cost because compressed air is continuously leaking while the unit is under pressure. With a 1 mm hole diameter at 190 psi, that leads to an annual cost of about $1000.00 when operating the system for 24 hours.
Slightly increased air consumption of about 3.5 cfm from an H.V.L.P spray gun for example only leads to an extra cost of about .02 – .05 cents for a partial coating.
Troubleshooting Chart
Coarse surface finishes, ...
… Orange peel, color matching problems and mottling.
Potential Causes of Malfunctions and Corrective Actions:
● Compressor too small or too many users; air line diameters too small.
○ Replace compressor
○ Reduce number of users
● Insufficient air volume
○ Replace the existing airlines ensuring that they have larger diameters. Rule of thumb: The longer the airline system, the larger the inner diameter required.
○ Install a larger surplus air tank providing for a higher compressed air reserve.
● Too many leaks in the air line
○ Repair leaks
○ Disconnect leaking users
○ Replace defective pipes
● Air flow of follow-up devices such as refrigerant dryer or filter is too low
○ Adapt performance data of follow-up devices to compressor or user
● Air hose with insufficient air flow rate
○ Use compressed air hoses with a minimum diameter of 9 mm
○ No coupling of hoses together; always use a hose having the correct length.
○ Use couplings with a free diameter of minimum 5.5 mm
○ Use hose fittings with a minimum diameter of 5.5 mm
● Air passages for air distribution to the nozzle dirty or clogged
○ Clean gun and check air cap pressure
○ Replace gun
● Air cap damaged or clogged
○ Clean air cap
○ Replace air cap, i.e. nozzle set
● Insufficient gun inlet pressure
○ Install a pressure regulation valve with manometer on the spray gun allowing you to adjust and to control the effective air inlet pressure on the spray gun. Alternative option: Install a manometer on the air inlet of the spray gun and adjust the pressure on the pressure reducer on the wall-mounted filter unit.
Coarse surface structure during coating …
… changes in color shades and / or mottling.
Potential Causes of Malfunctions and Corrective Actions:
● No pressure regulator connected
○ Install suitable pressure regulator
● Pressure regulator does not function or only irregularly
○ Repair or replace pressure regulator
● Filter cartridges are clogged
○ Replace or clean filter cartridges
● Diameter reduction due to teflon tape or rope pieces used for tightening fittings / connections
○ Remove teflon tape
○ Ensure tight fit by means of sealing rings or liquid sealing agent, i.e. Loctite
○ In case a teflon tape is indispensable, apply thoroughly and avoid diameter reductions or loose pieces
Silicone and oil …
… or condensation on the coating causing adhesion problems etc.
Potential Causes of Malfunctions and Corrective Actions:
● No or insufficient condensate separation in the compressed air
○ Use purpose-built water separators with particle filters as well as fine filter units from ITALCO.
● Filter units are installed at the wrong place in the airline system.
○ A filter unit consisting of a water separator and fine filter should be installed at each location where compressed air from the airline is being taken.
● Too high a temperature of the compressed air causes the condensate to be “pulled along”
○ Add cooling device
○ Increase pressure compensation container
○ Compressor is too small and gets hot. Can be seen in permanent compressor run. Install additional or larger compressor.
● Main compressed air line exit does not move upward in swanneck shape; condensate runs into exit.
○ Install airlines with an inclination of 1-2% and install condensate discharge valves and condensate collectors at the end of the airlines.
○ Install connections with swan necks above the actual airline.
○ Avoid sinks in the airline or install condensate discharge valves and condensate collectors
○ Install a water separator before the hose reel to prevent condensed water collecting in sinks
● The water separator does not continuously discharge condensate; filter is overfilled; the condensate is gradually pulled along
○ Install condensate discharge in the filter
○ Install automatic condensate discharge valve in the filter, or ensure that the manual discharge is activated frequently
○ Replace or repair and examine condensate discharge valve
● Due to the high heat expansion of the plastic (approx. 10 % at 20° C), low spots appear between the holding clamps (the line starts to sag)
○ Install galvanized steel pipe
○ Install stainless steel pipe
Never use copper, as air and condensate cause corrosion (verdigris may cause color shade changes)
Particles in paint finish, …
… what leads to expensive rework
Potential Causes of Malfunctions and Corrective Actions:
● Filter with inadequate filtration performance (too coarse) is installed
○ Always use fine filter with 0.01 µm. Water separator is insufficient.
● Flow performance of filter too low or filtration surface too small.
○ Particles are “pulled through” due to extremely high air speed inside the filter cartridge.
● Filter breaks through with very high pressure drop (Filter is blocked).
○ Frequently replace and clean filter cartridge (abide ny differential pressure)
○ Replace / clean filter cartridges (according to Operating Instructions) a minimum of once a year, because the air vibration causes particles / aerosols to “wander through” the filter after long operating time
● Filter is installed at the wrong place in the compressed air line
○ Install a suitable compressed air filter at each air outlet
Condensation / oil separation…
… despite the use of modern compressors. Surface craters caused by considerable condensate / oil separation at the nozzle.
Potential Causes of Malfunctions and Corrective Actions:
● An old compressor feeds lots of oil through its piston rings into the compressed air.
○ Replace piston rings and piston sleeves, or replace compressor
● When using a screw compressor, the air is lubricated and cooled by oil injected into the compressed air, which must be separated by the compressor’s main oil separation cartridge. Oil leakage is caused by insufficient service of this cartridge.
○ Conduct frequent service of the oil separation cartridge in accordance with operating instructions
○ Install automatic filter status indicator at the compressor
Please observe:
In case of condensate or particle flushes, please rinse the airlines with a sufficient amount of solvent and blow it thoroughly dry afterwards. In case of long and very tangled airlines, rinsing normally does not fix the problem – the entire airline system has to be replaced.
● The refrigerant dryer is installed at the wrong place in the compressed air circuit, i.e. is overcharged.
○ Increase refrigerant dryer
○ Install refrigerant dryer before the pressure compensation container
● Permanent compressor run causes the air streaming into the refrigerant dryer to be too hot; refrigerant dryer is too small.
○ Install aftercooler
○ Increase refrigerant dryer
○ Install refrigerant dryer after the compensation container, provided there are no excessive momentary charges.
Pressure drop…
… again and again lasting for a certain period of time
Potential Causes of Malfunctions and Corrective Actions:
● Too many heavy users, operated sporadically
Install additional compressor
○ Organize work in a way that excessive charges are eliminated or reduced
○ Install additional pressure compensation container for reducing the air volume capacity
● Installation of an absorption dryer
The auto-regeneration of the absorbtion dryer (cold regeneration) causes approx. 10 % of the compressed air volume to be blown into the atmosphere, even if no compressed air is being consumed
○ Uninstall absorption dryer
○ Install absorption dryer with warm regeneration
○ Instead of an absorption dryer, install a cold dryer which consumes no air
○ Install new, larger compressor
● Installation of an absorption dryer with warm regeneration. The absorption dryer with warm regeneration causes 2 – 3 % of the compressed air volume fed to be blown into the atmosphere.
○ Uninstall absorption dryer
○ increase compressor unit; install new compressor.
● Installation of a diaphragm dryer
The installation of a diaphragm dryer (HighTec) causes approx. 20 – 30 % of the air volume to be blown into the atmosphere, even when no compressed air is being consumed.
○ Uninstall diaphragm dryer
○ Enlarge compressor and compressed air system correspondingly
○ Install corresponding filtration
● Air line diameter reductions caused by dirt
○ Sufficiently clean and dry compressed air lines
● Too much dirt in the compressed air line may affect the function of the automatic condensate discharge and other valves
○ Replace valves and pipes
Insufficient air volume…
… despite sufficient dimensions and performance of the system, the filters become saturated very rapidly. High condensate concentrations and a lot of particles in the spray air.
Potential Causes of Malfunctions and Corrective Actions:
● Compressed air is sucked in from a wet or dusty area
■ Enlarge ventilation openings; if necessary install a fan
■ Install suction line “outside” of the area in question
● Compressed air suction is placed too close to the floor; thus it inhalesdust, moisture and possibly exhaust fumes (CO)
- Install suction line at a higher point; such as the back of the building, where dust and moisture do not occur; abide by wind direction.
● Suction filters of the compressor are “clogged”
■ Conduct suction filter service in accordance with compressor operating instructions; abide by or, if necessary, shorten service intervals
■ Replace suction filters