Wagner Systems [Tips & Tricks no. 6 - How to set the total air]

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Tips & Tricks no. 6 - How to adjust the air flows

After we discussed how to calculate the correct total air quantity in the last issue of our Tips & Tricks, it's now time to have a closer look at the setting procedure of the results we have obtained.

Remember: The correct total air with different hose diameters

Internal hose Ø	Powder velocity	Total air
9 mm	12 m/sec	2.7 m³/h
10 mm	12 m/sec	3.4 m³/h
11 mm	12 m/sec	4.1 m³/h
12 mm	12 m/sec	4.9 m³/h

Systems with automatic regulator (AFC in m3/h)

Here all you have to do is enter the total air through a keypad or by turning a swivel knob. The regulation then takes place automatically. The system operator can adjust the feed air, as required, to influence the size of the powder cloud. So that the velocity in the powder hose is kept constant, the dosage air is automatically regulated to suit.

First total air setting of manual coating systems

Injectors with orifice

The total air of plants with manual pressure control valves is somewhat more complex to adjust, depending on the configuration installation. Let's take a look at it on the basis of a concrete example with the following values:

Injector: PI-PF with orifice (recognizable from the black or partly black dosage air fitting)

Hose length: 6m / 20ft

Hose inside Ø: 11 mm

Powder velocity: 12 m/s / 40 ft/s

Total air: 4.1 Nm3/h

Powder: Epoxy Polyester (E/P)

Target powder quantity 100 g/min

Adjust the feed air until the desired powder cloud is obtained (e.g. 1 bar / 14.5 PSI).
Check the feed pressure on the pressure gauge. The corresponding feed air quantity in Nm3/h can be read on the outer scale of the pressure gauge.
Calculate the dosage air quantity:
Total air (4.1 Nm3/h) - feed air (2.0 Nm3/h) = dosage air (2.1 Nm3/h)
Now find the equivalent of the dosage air quantity on the pressure gauge and adjust accordingly (2.1 Nm3/h = 1.5 bar / 21.75 PSI).


Feed air		Dosage air

Increasing the powder throughput

Increase the feed air until the desired powder cloud is obtained (e.g. 2 bar / 29 PSI).
Check the feed pressure on the pressure gauge. The corresponding feed air quantity in Nm3/h can be read on the outer scale of the pressure gauge.
Total air (4.1 Nm3/h) - feed air (3.2 Nm3/h) = dosage air (0.9 Nm3/h)
Now find the equivalent of the dosage air quantity on the pressure gauge and adjust accordingly (0.9 Nm3/h = 0.7 bar / 10 PSI).

These settings apply to our example and can significantly vary depending on the hose length, the specific weight of the powder and other parameters.


Feed air		Dosage air

Injectors without orifice

Injectors without orifice are generally used with automatic air flow control. They are less suitable for systems with manual air adjustment. The setting range of the dosage air is very narrow here and adjustments become a rather painstaking task.

This is how the dosage air would have to be set for the two examples above:


2.1 Nm3/h Dosage air		0.9 Nm3/h Dosage air

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			Tips & Tricks

			Tips & Tricks
			1. The correct nozzle system

			2. The conductive powder hose

			3. The Powder Injector

			4. The correct powder velocity

			5. Calculating the total air

			6. Adjusting the airflows