Electrical operation group for air section

The electrical operation group of the air section comprises an electrical air pressure regulator, by-pass valve, discharge silencer, pressure gauge and shut-off valves. The air is sent from the compressor via a heat-proof air hose to the air pressure regulator group (A).

The air pressure regulator (C) has the following functions:

• Setting the required air pressure
• Maintaining the set air pressure at a constant level
• Safety valve

The electrical air pressure regulator works indirectly via a membrane, so that the pressure can be very accurately set within a range of 0.0-2.0 bar.

Never set the pressure higher than 2.0 bar, due to the maximum permissible air pressure of the machine. The air pressure regulator is fitted with a 12-V electrical motor to allow for remote control.

A damaged membrane or incorrect fitting of a membrane will result in leakage. This becomes apparent when air flows out of leakage hole (B) on the spring holder.

A-Air pressure regulator group
B-Air leakage hole
C-Air pressure regulator

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Both the liquid pressure and air pressure can be raised or lowered via the control box (ELC-1 or EHC-2) by setting the MAN/AUTO toggle switch 2 to manual operation (MAN). Switch 4 (+/- AIR) can then be used to raise or lower the air pressure. When the MAN/AUTO toggle switch is set to AUTO, the GreenStar Sprayer Control System automatically controls the air pressure, so that the set droplet size is automatically and continually regulated. A liquid pressure sensor (A) and an air pressure sensor (B) are then both fitted to the machine for that purpose. The sprayers also have a wind meter (C) fitted to the machine.

A-Liquid pressure sensor
B-Air pressure sensor
C-Wind meter

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IMPORTANT: The compressor must never be started with counter pressure. The by-pass valve must be opened before starting the compressor (Master valve closed).

The air pressure regulator group contains an electric by-pass valve (A). If the Master switch on the control box (ELC-1 or EHC-2) is closed, the air by-pass valve is opened. The compressor may never be started with counter pressure, i.e. the by-pass valve must be opened before starting the compressor. If the Master valve is closed, then the by-pass valve is open. If the Master valve is open, then the by-pass valve is closed. The by-pass valve may only be closed in order to build up pressure once the compressor is at an adequate speed.

The air is pumped at the set pressure via a heat-proof hose to the air sectional valves at the back of the machine. The unused air is blown out via the air pressure regulator and a discharge silencer (B).

A-By-pass valve
B-Discharge silencer

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The set air pressure is displayed digitally on the GreenStar display. As standard, the machine is fitted with a digital air pressure sensor (B) for that purpose, which is mounted to the rear centre of the spray boom.

The analogue air pressure gauge (A) only has a monitoring function. The pressure gauge is located in the pressure line at the pressure regulator and gives the pressure there in bar. The pressure gauge has a 100 mm diameter and a phased scale of 0-10/25 bar. The accuracy (KI) is 1.0% in the 0-10 bar area, i.e. 0.25 bar. The pressure gauge is filled with glycerine to prevent the pointer from vibrating.

The pressure given on the GreenStar display is much more accurate and is always lower than the air pressure on the pressure gauge during spraying, due to pressure losses in the line. Depending on the output, the air pressure at the nozzles will always be slightly lower than the air pressure on the display due to pressure losses in the lines. Make allowances for this when calibrating the spray nozzles.

A-Air pressure gauge
B-Air pressure sensor

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The air is pumped from the air pressure regulator via a heat-proof hose to the electrical air shut-off valves (A). The machine has equal numbers of air and liquid sectional shut-off valves, of course. The sections for the air parts are closed off by means of electromagnetic valves, fitted to the rear of the spray boom.

Operation of the sectional shut-off valves for the air and liquid takes place simultaneously and can be simply controlled from the operating panel (ELC-1 or EHC-2). If the section in question is open (LED is ON), the shut-off valves for both the air and the liquid are open (when main switch M is switched on), if the section is closed (LED is OFF), the shut-off valves in question are closed.

A-Electro-magnetic sectional shut-off valves

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