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Spray Gun - Spray Gun Connection and Adjustment
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Spray Gun Connection and Adjustment |
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Spray Gun Pressure Settings:
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Set the spray pressure to appropriate level according to the paint used and the size of area to be painted. | |
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The air pressure is usually initially adjusted at the regulator, which may be some distance from the spray gun. Because of pressure drop caused by the length and diameter of the air hose, the gun pressure may differ significantly from the remote regulator. Therefore, best practice requires a second small air pressure gauge mounted to the spray gun. Use this second gauge to set the correct spraying pressure. | |
Air Hose Pressure Drop Calculation Chart
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Air Hose |
Regulator |
Length of Air Hose, m (ft) |
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Inside Diameter (ID) |
Pressure |
4.5 m
(15 ft) |
7.5 m
(25 ft) |
15 m
(50 ft) |
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mm (in) |
kPa (kgf/cm2, psi) |
Pressure at End of Air Hose
kPa (kgf/cm2, psi) |
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6 (0.24) |
340 (3.5, 50) |
260 (2.7, 38) |
210 (2.1, 30) |
150 (1.5, 22) |
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410 (4.2, 60) |
310 (3.2, 45) |
270 (3.2, 40) |
190 (1.9, 28) |
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480 (4.9, 70) |
360 (3.7, 52) |
320 (3.3, 46) |
250 (2.5, 36) |
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8 (0.31) |
340 (3.5, 50) |
310 (3.2, 45) |
310 (3.2, 45) |
270 (2.8, 40) |
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410 (4.2, 60) |
380 (3.9, 55) |
370 (3.8, 54) |
330 (3.4, 48) |
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480 (4.9, 70) |
440 (4.5, 64) |
430 (4.4, 62) |
400 (4.1, 58) | |
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As the distance of the paint gun from the surface being painted increases, the spray pattern size increases. The paint film gets thinner and more paint is lost as overspray. If the paint gun is too close to the surface being painted, the paint will be applied too heavily, causing runs. Generally, the recommended distance for lacquer type paint is approximately 20 cm (8 in), and approximately 25 cm (10 in) for acrylic urethane type paint.
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In general, the optimum distance between the paint gun and surface being painted is 15?25 cm (6?10 in).
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Spray Pattern Adjustment:
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The spray pattern can be adjusted using the pattern and fluid adjustment screws on the spray gun. | |
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If the spray pattern has a rough surface or edge, Regulate the fluid flow using the fluid adjustment screw, or reduce the air volume by adjusting the air volume adjustment screw. | |
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If the paint runs, reduce the fluid flow rate. Also check the paint’s viscosity and the paint reducer/thinner’s evaporation rate. | |
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NOTE: Be sure to check the product specifications issued by the paint manufacturers as each spray gun has different settings for the paint patterns and distance. | |
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General Recommended Patterns:
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Spot Painting Pattern
Adjust the pattern and fluid flow rate adjustment screws to create a pattern diameter of 12?13 cm (4.75?5 in) at a distance of 15?20 cm (6?8 in) away from the surface.
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Overall Painting Pattern
Adjust the pattern and fluid flow rate adjustment screws to create a pattern diameter of 22?23 cm (8.75?9 in) at a distance of 15?20 cm (6?8 in) away from the surface.
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