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
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 SiliconePlastics based on a silicon-oxygen structure.Silicone and silicon-based substances have various fields of application in technology and chemistry. Besides industrial use, the sector of construction coatings appreciates aquaeous dispersions of silicone resins (silicone emulsions)for the application of water repellent finishing on walls.Silicone-based substances change the surface tension. Even very small silicone particles can cause considerable coating flaws (silicone craters). Therefore, silicone-based substances (e.g. gloves, oil etc.) must never be used in coating areas.X» (fish eyes) and shorten the function and lifetime of pumps and pneumatic tools. Have your Compressed air qualityAir composition regarding oil, dust and water content.The standard DIN ISO 8573-1 defines the compressed air quality categories with regard to: :Oil contentDefinition of the remaining quantity of aerosols and hydrocarbons the compressed air may contain.Particle size and densityDefinition of size and concentration of solid particles compressed air may still contain.Dew point under pressureDefinition of the temperature to which the compressed air may be cooled down without condensation of the steam contained in it. The dew point under pressure varies with the air pressure.X» checked. Find more detailed information in the Product Service section. With the 0/400 modular filter series, we offer a solution according to your requirements and support you by providing the best solution.
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 HVLPHVLP = High Volume Low Pressure - low spray pressure technology.Terminology for an internationally recognized low-pressure technology whereby the transfer efficiency rate has to exceed 65%, while the maximum air cap pressure is below 0.7 bar.X» 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.
Reason
Potential Causes of Malfunctions and Corrective Actions:
Compressor too small or too many users; air line diameters too small.
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
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 PressureAir cap pressure is air pressure inside the air cap of the spray gun. It must not exceed with HVLP guns 10 psi (0,7 bar), for verification there are test air caps with gauges for round and flat spray air available.X»
Air cap damaged or clogged
Replace air cap, i.e. nozzle set
Insufficient gun Inlet PressureThe inlet pressure on the spray gun should always be correctly adjusted. This is particularly easy with the DIGITAL technology of the SATAjet 5000 DIGITAL or with the retrofit SATA adam 2. It is also possible, however, to connect a standard air micrometer with manometer to the gun. Since pressure in combination with the supply of compressed air (air consumption) has a great influence on optimum results, you should always ensure to set the inlet pressure as recommended. You will find information on the correct pressure to be used in the paint application sheet of the paint manufacturers or on the web pages reserved for each individual SATA spray gun.X»
Install a pressure regulation valve with manometer on the spray gun allowing you to adjust and to control the effective air Inlet PressureThe inlet pressure on the spray gun should always be correctly adjusted. This is particularly easy with the DIGITAL technology of the SATAjet 5000 DIGITAL or with the retrofit SATA adam 2. It is also possible, however, to connect a standard air micrometer with manometer to the gun. Since pressure in combination with the supply of compressed air (air consumption) has a great influence on optimum results, you should always ensure to set the inlet pressure as recommended. You will find information on the correct pressure to be used in the paint application sheet of the paint manufacturers or on the web pages reserved for each individual SATA spray gun.X» on the spray gun. Alternative option: Install a manometer on the air inlet of the spray gun and adjust the pressure on the Pressure reducerIn most cases, it is just one part of a multi-stage filter unit. It is, however, also available as a stand-alone air pressure regulation unit, SATA filter 420, or for the regulation of the material pressure (see also material pressure regulator).X» on the wall-mounted filter unit. Please also refer to: How do I correctly adjust the pressure?
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Coarse surface structure during coating ...
... changes in color shades and / or mottling.
Reason
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
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
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SiliconePlastics based on a silicon-oxygen structure.Silicone and silicon-based substances have various fields of application in technology and chemistry. Besides industrial use, the sector of construction coatings appreciates aquaeous dispersions of silicone resins (silicone emulsions)for the application of water repellent finishing on walls.Silicone-based substances change the surface tension. Even very small silicone particles can cause considerable coating flaws (silicone craters). Therefore, silicone-based substances (e.g. gloves, oil etc.) must never be used in coating areas.X» and oil ...
... or condensation on the coating causing adhesion problems etc.
Reason
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 SATA.
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"
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)
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Particles in paint finish, ...
… what leads to expensive rework
Reason
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
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Condensation / oil separation...
... despite the use of modern compressors. Surface craters caused by considerable condensate / oil separation at the nozzle.
Reason
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.
Increase refrigerant dryer
Install refrigerant dryer after the compensation container, provided there are no excessive momentary charges.
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Pressure drop...
... again and again lasting for a certain period of time
Reason
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
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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.
Reason
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
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